speech and vision problems

• Patient Care & Health Information
• Diseases & Conditions

Dysarthria occurs when the muscles you use for speech are weak or you have difficulty controlling them. Dysarthria often causes slurred or slow speech that can be difficult to understand.

Common causes of dysarthria include nervous system disorders and conditions that cause facial paralysis or tongue or throat muscle weakness. Certain medications also can cause dysarthria.

Treating the underlying cause of your dysarthria may improve your speech. You may also need speech therapy. For dysarthria caused by prescription medications, changing or discontinuing the medications may help.

Products & Services

• A Book: Mayo Clinic Family Health Book, 5th Edition
• Newsletter: Mayo Clinic Health Letter — Digital Edition

Signs and symptoms of dysarthria vary, depending on the underlying cause and the type of dysarthria. They may include:

• Slurred speech
• Slow speech
• Inability to speak louder than a whisper or speaking too loudly
• Rapid speech that is difficult to understand
• Nasal, raspy or strained voice
• Uneven or abnormal speech rhythm
• Uneven speech volume
• Monotone speech
• Difficulty moving your tongue or facial muscles

When to see a doctor

Dysarthria can be a sign of a serious condition. See your doctor if you have sudden or unexplained changes in your ability to speak.

In dysarthria, you may have difficulty moving the muscles in your mouth, face or upper respiratory system that control speech. Conditions that may lead to dysarthria include:

• Amyotrophic lateral sclerosis (ALS, or Lou Gehrig's disease)
• Brain injury
• Brain tumor
• Cerebral palsy
• Guillain-Barre syndrome
• Head injury
• Huntington's disease
• Lyme disease
• Multiple sclerosis
• Muscular dystrophy
• Myasthenia gravis
• Parkinson's disease
• Wilson's disease

Some medications, such as certain sedatives and seizure drugs, also can cause dysarthria.

Complications

Because of the communication problems dysarthria causes, complications can include:

• Social difficulty. Communication problems may affect your relationships with family and friends and make social situations challenging.
• Depression. In some people, dysarthria may lead to social isolation and depression.
• Daroff RB, et al., eds. Bradley's Neurology in Clinical Practice. 7th ed. Elsevier; 2016. https://www.clinicalkey.com. Accessed April 10, 2020.
• Dysarthria. American Speech-Language-Hearing Association. https://www.asha.org/public/speech/disorders/dysarthria/. Accessed April 6, 2020.
• Maitin IB, et al., eds. Current Diagnosis & Treatment: Physical Medicine & Rehabilitation. McGraw-Hill Education; 2020. https://accessmedicine.mhmedical.com. Accessed April 10, 2020.
• Dysarthria in adults. American Speech-Language-Hearing Association. https://www.asha.org/PRPPrintTemplate.aspx?folderid=8589943481. Accessed April 6, 2020.
• Drugs that cause dysarthria. IBM Micromedex. https://www.micromedexsolutions.com. Accessed April 10, 2020.
• Lirani-Silva C, et al. Dysarthria and quality of life in neurologically healthy elderly and patients with Parkinson's disease. CoDAS. 2015; doi:10.1590/2317-1782/20152014083.
• Signs and symptoms of untreated Lyme disease. Centers for Disease Control and Prevention. https://www.cdc.gov/lyme/signs_symptoms/index.html. Accessed April 6, 2020.
• Neurological diagnostic tests and procedures fact sheet. National Institute of Neurological Disorders and Stroke. https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Neurological-Diagnostic-Tests-and-Procedures-Fact. Accessed April 6, 2020.

Associated Procedures

• EEG (electroencephalogram)
• Electromyography (EMG)
• Lumbar puncture (spinal tap)
• Symptoms & causes
• Diagnosis & treatment
• Doctors & departments

Mayo Clinic does not endorse companies or products. Advertising revenue supports our not-for-profit mission.

• Opportunities

Mayo Clinic Press

Check out these best-sellers and special offers on books and newsletters from Mayo Clinic Press .

• Mayo Clinic on Incontinence - Mayo Clinic Press Mayo Clinic on Incontinence
• The Essential Diabetes Book - Mayo Clinic Press The Essential Diabetes Book
• Mayo Clinic on Hearing and Balance - Mayo Clinic Press Mayo Clinic on Hearing and Balance
• FREE Mayo Clinic Diet Assessment - Mayo Clinic Press FREE Mayo Clinic Diet Assessment
• Mayo Clinic Health Letter - FREE book - Mayo Clinic Press Mayo Clinic Health Letter - FREE book

Your gift holds great power – donate today!

Make your tax-deductible gift and be a part of the cutting-edge research and care that's changing medicine.

• Slurred Speech

6 Causes of Slurred Speech

Slurred speech quiz

Take a quiz to find out what's causing your slurred speech.

6 most common cause(s)

Take slurred speech quiz

Get personalized answers to your health questions

Our clinically-backed AI will ask you questions and provide an answer specific to your unique health situation.

Your response today was provided by ChatGPT trained on the proprietary content of this page. Please note, this tool is for information purposes only and not intended to be used as a substitute for professional advice. You assume responsibility for decisions made with your individual medical situation.

What is slurred speech?

Slurred speech is when you have trouble speaking, your words are slow or garbled, or your words run together. When you talk, many components of your nervous system work together to form words. When these parts don’t work correctly, your speech can become distorted, or “slurred.” The medical term for slurred speech is dysarthria.

Slurred speech includes problems pronouncing words and regulating the speed or pace of your speech. It can range from a barely noticeable problem to one that’s so severe that others can’t understand what you’re saying.

People often describe slurred speech as feeling like you’re trying to talk with your mouth full of marbles.

Common causes of slurred or slow speech include drinking too much alcohol and not getting enough sleep. In these cases, the slurring will stop once you’re sober again and have gotten rest, respectively.

There are also other causes of slurred speech such as a stroke (a medical emergency), brain tumor, Bell’s palsy, or a serious migraine.

Does slurred speech always need to be treated?

"People often think slurred speech is a minor symptom that does not need a medical evaluation. As our speech and ability to speak is our main form of communication, it is important to look for correctable causes." — Dr. Karen Hoerst

Should I go to the ER for slurred speech?

You should call 911 if:

• Your slurred speech starts suddenly.
• You have other symptoms, such as a sudden or severe headache and weakness or numbness of one side of your body.
• Your tongue, face, or lips are swelling, which could mean you’re having an allergic reaction.

1. Stroke or TIA (transient ischemic attack)

• Slurred speech
• Drooping of one side of the face
• Weakness or trouble controlling one side of the body
• Numbness in the face , arm , or leg
• Difficulty walking
• Sudden loss of vision or double vision
• Sudden, severe headache

A stroke occurs in the brain because the blow flow in a blood vessel is blocked. It can also happen when a blood vessel ruptures or leaks. This affects the blood supply to parts of the brain, which leads long-term damage. If it affects the area of the brain responsible for speech, it can cause slurred speech.

A transient ischemic attack , or TIA, is sometimes called a "mini stroke." A TIA is a temporary interruption of blood flow that causes the same symptoms as a stroke, but improves without any permanent damage to the brain or symptoms.

For example, if you have slurred speech because of a TIA, once the blood flow is restored to that area of the brain, the slurred speech goes away. But people who have a TIA are at a high risk of having a stroke in the future, especially if their risk factors are not treated. Risk factors are the same for stroke and TIA and include smoking, obesity, and cardiovascular disease.

It’s extremely important to call 911 right away if you suddenly have slurred speech. Getting immediate treatment is critical to minimizing permanent damage. Paramedics can begin treating you in the ambulance on the way to the hospital, so it’s better to call 911 than go to the ER yourself.

Treatments for strokes and TIAs include medications to break up blood clots and surgery to remove blood clots from the vessels. If your stroke is from bleeding in the brain, you may need surgery to repair a blood vessel.

Following treatment, your doctor will recommend medications to prevent another TIA or stroke. These typically include drugs that prevent clots from forming in the blood (like aspirin or other blood thinners) and cholesterol medication to prevent plaque from building up on the walls of the blood vessels. You may also need to take medication to control your blood pressure.

Speech therapy is recommended to help treat problems with speech.

It may not be a stroke

"There are so many possible causes of slurred speech. Most of the time we need a detailed history and physical exam to guide the diagnosis and treatment." — Dr. Hoerst

2. Bell’s palsy

• Drooping of the face
• Drooping of the eye
• Changes in taste or hearing

Bell’s palsy is a relatively common condition that affects the facial nerve, which is responsible for movement of your face.

In Bell’s palsy, the nerve gets inflamed typically because of a recent viral infection. This inflammation can cause the facial nerve to not work as well, leading to drooping and slurred speech.

Bell’s palsy usually improves in a few months, but medications such as steroids and antiviral drugs are typically given to help speed the process. If nerve problems continue, physical therapy is recommended. In rare instances, surgery may be needed to help improve facial muscle function.

3. Brain tumor

• Slurred speech or speech difficulties
• New or changing headaches
• Weakness or coordination and balance problems
• Abnormal vision

A brain tumor is an abnormal growth of cells in the brain. A brain tumor may be cancerous (malignant) or noncancerous (benign). Both types can cause symptoms including slurred speech.

The diagnosis of a tumor in the brain or spinal cord is based on an exam and imaging of the brain, such as an MRI or CT scan. A biopsy (tissue sample) may be needed to determine what type of tumor it is.

Some tumors, such as a small noncancerous tumor, do not need treatment, though your doctor will recommend periodic MRI scans to make sure it hasn’t changed.

Most larger or cancerous tumors do require treatment, which may consist of chemotherapy, radiation, or surgery. If you develop physical or cognitive (mental) problems from the tumor, rehabilitation such as physical therapy, occupational therapy, or speech therapy may be needed.

4. Multiple sclerosis

• Blurred vision or decreased vision, typically in one eye
• Weakness or trouble walking
• Numbness or pins-and-needles sensation on your face, arm, or leg (typically on one side)
• A band-like squeezing sensation around the chest or abdomen
• Difficulty focusing

Multiple sclerosis, or MS, is a central-nervous system disease that affects the cells of the brain and spinal cord. In MS, a fatty tissue that surrounds nerve fibers (myelin) is attacked. Myelin helps to insulate the electrical signals sent through the nerves. When there is a problem with this fatty tissue, information sent to and from the brain can be disrupted.

MS is most common in young adults between the ages of 20 and 50, according to the National MS Society .

MS is not curable , but treatments have dramatically improved the ability to control MS, so people usually have fewer symptoms and less disability.

Treatment includes medications that may be taken orally or injected or infused through an IV line. Physical therapy and speech therapy are commonly used to help in physical recovery, and medications can be used to treat other symptoms, such as depression, pain, and fatigue.

5. Amyotrophic lateral sclerosis (ALS)

• Difficulty with speech, including slurred speech
• Progressive weakness and difficulty balancing
• Muscle cramps, twitching, and stiffness
• Difficulty swallowing

Amyotrophic lateral sclerosis (ALS) is also known as Lou Gehrig’s disease. It affects nerve cells called motor neurons that control your movement.

The disease primarily causes a loss of strength, impaired swallowing and speech, and in most cases, difficulty breathing because of impaired respiratory muscles. It is a progressive disease, meaning that symptoms are mild at first and worsen over time.

Previously, it was thought that ALS doesn’t affect a person’s mental ability. But it’s now known that people with ALS can get a specific type of dementia called frontotemporal dementia (FTD). That condition can affect behavior, mood, and speech.

Symptoms of ALS can develop in adults of any age, but it’s most commonly diagnosed in people who are between the ages of 40 and 70, according to the ALS Association .

While there are some medications that can be used to delay the progression of the disease, there is currently no cure for ALS. Treatment includes rehabilitation with physical therapy, occupational therapy, speech therapy, and respiratory therapy.

6. Migraine

• Sensitivity to light and sound
• Visual disturbances

A migraine causes a severe headache that is often accompanied by nausea and sensitivity to light or sound. But some migraines don’t cause head pain.

Other symptoms that involve the nervous system can occur. Some of these sensory symptoms are called “auras.” These distortions can cause visual changes , including flashing lights or distorted vision. People may feel tingling or numbness of their face, arm, or leg.

In some types of migraine, people may even develop slurred speech and weakness of the face, arm, or leg. These are also symptoms of a stroke, so it may be hard to figure out which condition you have. If you develop sudden slurred speech or weakness, go to the ER immediately.

In an acute migraine attack, medications can be used to stop a migraine that has already started, such as triptans or newer medications called CGRP inhibitors. These medications can be in pill form, inhaled form, or injectable medications.

Migraine prevention can include taking medications for blood pressure, anticonvulsants, or even antidepressants. In some instances, Botox treatments are used to prevent migraine.

Behavior and lifestyle changes such as exercise, improved sleep, and healthy diet or weight loss are also often recommended to help decrease the number of migraine headaches you experience.

Other possible causes

Slurred speech may occur from alcohol intoxication or tiredness. It can also be a side effect of medications like high dose pain medications, antipsychotic medications or even some allergy medications like antihistamines. Other causes include:

• Infections such as urinary tract infections or electrolyte imbalances (particularly in elderly people).
• Brain infections such as meningitis or encephalitis.
• Problems that affect your mouth or throat, such as poorly fitting dentures, dental infections, dental numbing medications, swelling in your throat, or muscle or nerve problems.
• An allergic reaction , especially if you notice slurred speech along with tongue swelling , lip swelling, or shortness of breath.

"Early speech therapy can not only help with early improvement but also with diagnosis. Speech-language pathologists have special training in detecting the various types of slurred speech, which helps to determine the possible causes."— Dr. Hoerst

Specialty treatment options

• Speech therapy is the most common treatment for slurred speech.
• Injected medications such as Botox are sometimes used, depending on the cause of slurred speech.
• Medications to improve nerve and muscle function.

While it's important to follow your healthcare provider's guidance, here are some over-the-counter (OTC) options that might provide extra support.

• Proper nutrition supports overall health, including nerve function. Supplements like B vitamins may support neurological health.
• Staying hydrated is key, especially if speech difficulties make it hard to drink. Consider a no-spill, easy-sip water bottle designed for easy grip.
• Engaging in exercises to improve speech clarity can be helpful. Explore speech therapy tools and resources that you can use at home.

Required field

Was this article helpful?

• Share full article

Advertisement

Supported by

Personal Health

How Vision Loss Can Affect the Brain

A growing body of evidence suggests that when older people’s brains have to work harder to see, declines in language, memory, attention and more could follow.

By Jane E. Brody

Medical practice tends to divide its clients — you and me — into specialties defined by body parts: ophthalmology, neurology, gastroenterology, psychiatry and the like. But in fact, the human body doesn’t function in silos. Rather, it works as an integrated whole, and what goes awry in one part of the body can affect several others.

I’ve written about the potential harm of hearing loss to brain health, as well as to the health of our bones , hearts and emotional well-being .

Untreated hearing loss can increase the risk of dementia. Even those with slightly less than perfect hearing can have measurable cognitive deficits.

Now, a growing body of research is demonstrating that vision loss can affect the brain’s function, too. As with hearing, if the brain has to work extra hard to make sense of what our eyes see, it can take a toll on cognitive function.

The latest study, published in JAMA Network Open in July, followed 1,202 men and women aged 60 to 94 for an average of nearly seven years. All were part of the Baltimore Longitudinal Study of Aging, and had vision and cognition tests every one to four years between 2003 and 2019.

The researchers found that those who scored poorly on initial tests of visual acuity — how well, for example, they could see the letters on an eye chart from a given distance — were more likely to have cognitive decline over time, including deficits in language, memory, attention and the ability to identify and locate objects in space.

Other vision issues, like with depth perception and the ability to see contrasts, also had deleterious effects on cognitive ability.

The lead researcher, Bonnielin Swenor, an epidemiologist at the Johns Hopkins Wilmer Eye Institute, said that the new study “adds to mounting longitudinal data showing that vision impairment can lead to cognitive decline in older adults.”

Correcting poor vision is good for the brain.

Lest you think that the relationship is reversed — that cognitive decline impairs vision — another study that Dr. Swenor participated in showed that when both functions were considered, vision impairment was two times more likely to affect cognitive decline than the other way around. This study, published in 2018 in JAMA Ophthalmology and led by Diane Zheng from the University of Miami Miller School of Medicine, included 2,520 community-dwelling adults ages 65 to 84, whose vision and cognitive function were periodically tested. She and her co-authors concluded that maintaining good vision as one ages may be an effective way to minimize the decline in cognitive function in older adults.

“When people have vision loss, they change the way they live their lives. They decrease their physical activity and they decrease their social activity, both of which are so important for maintaining a healthy brain,” Dr. Swenor said. “It puts them on a fast tack to cognitive decline.”

But identifying and correcting vision loss early on can help, Dr. Zheng said. She suggested regular eye checkups — at least once every two years, and more often if you have diabetes, glaucoma or other conditions that may damage vision. “Make sure you can see well through your glasses,” she urged.

When glasses alone aren’t enough

There are “vision impairments that glasses won’t fix,” Dr. Swenor said, like age-related macular degeneration and glaucoma. Retinal disease began to compromise Dr. Swenor’s vision in her mid-20s. Those with problems like hers can benefit from something called low vision rehabilitation , a sort of physical therapy for the eyes that helps visually impaired people adapt to common situations and help them function better in society.

Dr. Swenor, for instance, can see objects in a high-contrast situation, like a black cat against a white fence, but has trouble seeing the difference between similar colors. She can’t pour white milk into a white mug without spilling it, for example. Her solution: Use a dark-colored mug. Finding such accommodations is an ongoing task, but it enables her to continue to function well professionally and socially.

Society, too, needs to help people with visual impairment function safely outside the home. Most things in hospitals are white, for example, which creates safety hazards for people with diminished contrast sensitivity. As a driver of 50 years, I’ve noticed that road barriers that used to be the same color as the road surface are now more often rendered in high contrast colors like orange or yellow, which undoubtedly reduces crashes even for people who can see perfectly.

“We need to create a more inclusive society that accommodates people with vision impairment,” Dr. Swenor said.

Home improvements may foster brain health

People who have trouble with depth perception can also incorporate helpful design features into the home. Placing colored strips on stair risers, varying textures of furniture and color-coding objects can all improve the ability to navigate safely. People who can no longer read books may also listen to audiobooks, podcasts or music instead, Dr. Swenor said.

The link between visual impairment and cognitive impairment “is not a doomsday message,” she added. “There are many ways to foster brain health for people with vision loss.”

Step one may be getting a Medicare extension bill through congress, which in turn might prompt private insurers to also cover vision care and rehabilitation. The Democrats’ current proposal to extend Medicare benefits to cover vision care would more than pay for itself in the long run by diminishing already-covered medical costs for cognitive and physical decline.

Case in point: The cost of a single hip replacement resulting from a vision-impaired fall would exceed the cost of many hundreds of eye exams and needed vision corrections.

Jane Brody is the Personal Health columnist, a position she has held since 1976. She has written more than a dozen books including the best sellers “Jane Brody’s Nutrition Book” and “Jane Brody’s Good Food Book.” More about Jane E. Brody

Jane Brody’s Personal Health Advice

After joining the new york times in 1965, she was its personal health columnist from 1976 to 2022. revisit some of her most memorable writing:.

Brody’s first column, on jogging , ran on Nov. 10, 1976. Her last, on Feb. 21. In it, she highlighted the evolution of health advice  throughout her career.

Personal Health has often offered useful advice and a refreshing perspective. Declutter? This is why you must . Cup of coffee? Yes, please.

As a columnist, she has never been afraid to try out, and write about, new things — from intermittent fasting  to knitting groups .

How do you put into words the pain of losing a spouse of 43 years? It is “nothing like losing a parent,” she wrote of her own experience with grieving .

Need advice on aging? She has explored how to do it gracefully ,  building muscle strength  and knee replacements .

A monthly newsletter from the National Institutes of Health, part of the U.S. Department of Health and Human Services

Search form

September 2012

Print this issue

See, Hear, Speak

Are Kids’ Senses Ready for School?

When setting off for kindergarten or first grade, a child may feel prepared with a backpack loaded with crayons, pencils, and paper. But a good start in the classroom depends on more than just school supplies. Healthy hearing, vision, speech, and language are key to success at school. If a child has problems in these areas, the sooner they’re spotted, the better they can be treated.

Sometimes problems with senses, speech, or language fly under the radar. A child with a lazy eye or a little hearing loss might get along just fine at home or in daycare. But when children get to school, minor difficulties may start to catch up with them. They may have trouble focusing and flourishing in the classroom. NIH-funded scientists are searching for better ways to recognize and treat these types of problems as early as possible.

Nearly all newborns are screened for hearing loss before leaving the hospital. For newborns diagnosed with hearing loss, interventions such as hearing aids or cochlear implants should begin no later than 6 months of age. When interventions begin early, children with hearing loss can develop language skills that help them communicate.

Hearing problems can also arise in older kids. “Some children are born with normal hearing and develop hearing loss later for various reasons,” says Dr. Mary Pat Moeller, who studies childhood deafness and language development at Boys Town National Research Hospital in Nebraska. Head injuries, meningitis, and chronic fluid behind the eardrum from repeated bouts of ear infections are just a few conditions that can lead to later hearing loss.

“We rely on normal hearing to pick up concepts and learn new words,” Moeller says. But a noisy classroom can be tough for kids who can’t hear well. “Children with undetected hearing loss may look like they have attention deficits. They may miss what they’ve been told because they’re just not hearing clearly,” she says.

Screening for hearing loss in school-age kids is a familiar process. Children wear headphones and raise their hands as they hear a series of tones. Some 5% to 10% of school-age children don’t pass these tests. Kids with hearing loss can be fitted with hearing aids or benefit from cochlear implants or assistive devices. For example, teachers can wear microphones that send their voices directly to the children’s ears. Even children with minimal hearing loss can benefit from this type of technology.

Children learn language by listening to others and engaging in conversations. But kids with hearing loss can miss out on some of this experience. Moeller and her colleagues are studying how children with hearing loss develop language. Results from this NIH-funded research point to several factors that can help. These include the quality and fit of hearing aids, how often kids get speech and language training, and how often parents have conversations with their children.

A different source of language problems is a disorder called specific language impairment, or developmental language disorder. This condition affects an estimated 7% of children in kindergarten. Kids with specific language impairment have trouble learning new words and engaging in conversation. They might produce grammatically incorrect sentences like “What he want for dinner?” or they might have a small vocabulary.

“Both of those are fundamental to being able to communicate with the teacher, to understanding what the teacher is saying to them, and to forming social relationships with their peers,” says Dr. Mabel Rice, an NIH-funded researcher who studies childhood language disorders at the University of Kansas.

For example, a child with specific language impairment might not understand that “It’s time to put your things away now” means “Put your things away.” Children who don’t understand complicated sentences can seem like they’re disobedient, Rice says. More complicated grammar is also good for making friends. Saying “I would like it if you’d come play with me” might attract more playmates than “Come over here.”

In the past, parents were sometimes blamed for a child’s language disability. They might have been faulted for not reading enough to their children. But research suggests that specific language impairment has other roots. The disorder tends to run in families, which hints that genes Stretches of DNA, a substance you inherit from your parents, that define characteristics such as how likely you are to get certain diseases. play a role. Rice led a study of over 300 people, including children with specific language impairment and their families. The scientists identified a gene that’s also linked to dyslexia and other learning disabilities. The finding might eventually lead to better understanding and treatment for these disorders.

Kids don’t usually grow out of specific language impairment. Their language improves, but they can continue to struggle with subtleties even after they enter the workforce. “It is very important to identify these kids, particularly at school entry or before school entry,” Rice says. Many school districts screen children for specific language impairment before kindergarten. Language therapy can help children catch up.

Poor vision can also cause trouble in school, and the problems may go unnoticed. Vision problems are common in preschoolers, but kids don’t always tell others about their symptoms. Children might even think it’s normal to see double or for things to be blurry. But poor eyesight can cause headaches and hinder reading. Some children with vision problems might seem to have attention difficulties, since eyestrain and headaches can make it hard to stay on task.

The most common cause of vision impairment in children is amblyopia, or lazy eye. It often arises if the eyes point in different directions, or if one eye produces a better image than the other. The brain starts to shut down signals from the weaker eye. Treatment encourages use of the weaker eye, sometimes by putting a patch over the other eye. NIH-funded research has found that treatment for amblyopia is more effective if begun when a child is young.

Some children are nearsighted, with problems focusing on faraway objects like the chalkboard. It’s less common for youngsters to be farsighted, with trouble focusing on up-close items. Both can be corrected with eyeglasses or contact lenses.

To catch problems early, NIH funded a study of thousands of preschoolers to find the best ways to screen for impaired vision. “How often screening is done and what screening is done varies widely from state to state,” says Dr. Marjean Kulp, a vision researcher at Ohio State University.

The study evaluated different tests and identified a few that could best detect vision problems—even when performed by people who aren’t vision specialists.

Screenings only identify potential problems, and they don’t catch everything. Children should have regular exams by an eye care professional.

Early detection and treatment of hearing, vision, and language problems can give kids a better learning experience.

Related Stories

Decoding Dyslexia

Enter NIH’s Youth Art Challenge on Prevention

Helping a Child Who Is Overweight

Addressing Childhood Bullying

NIH Office of Communications and Public Liaison Building 31, Room 5B52 Bethesda, MD 20892-2094 [email protected] Tel: 301-451-8224

Editor: Harrison Wein, Ph.D. Managing Editor: Tianna Hicklin, Ph.D. Illustrator: Alan Defibaugh

Attention Editors: Reprint our articles and illustrations in your own publication. Our material is not copyrighted. Please acknowledge NIH News in Health as the source and send us a copy.

For more consumer health news and information, visit health.nih.gov .

For wellness toolkits, visit www.nih.gov/wellnesstoolkits .

Sensory or Communication Disorders

Goal: prevent sensory and communication disorders and improve quality of life for people who have them..

Many people in the United States will have a sensory or communication disorder in their lifetime. This includes problems with vision, hearing, balance, smell, taste, voice, speech, or language.    Healthy People 2030 focuses on preventing, diagnosing, and treating these disorders in people of all ages.

Sensory or communication disorders can have a major impact on social, emotional, and physical well-being. Some groups have a higher risk of these disorders, including people with low incomes, people who work in certain industries, and older adults. People who are diagnosed or treated later often have worse outcomes.

Preventive care like hearing screenings for newborns and comprehensive eye exams in adults are critical for finding and treating these disorders early. And strategies to increase use of eye and hearing protection can help prevent new cases.

Objective Status

Learn more about objective types

Related Objectives

The following is a sample of objectives related to this topic. Some objectives may include population data.

Sensory or Communication Disorders — General

• Adolescents

Health Care

People with disabilities.

• Preventive Care

Public Health Infrastructure

Other topics you may be interested in.

• Child and Adolescent Development
• Infectious Disease

The Office of Disease Prevention and Health Promotion (ODPHP) cannot attest to the accuracy of a non-federal website.

Linking to a non-federal website does not constitute an endorsement by ODPHP or any of its employees of the sponsors or the information and products presented on the website.

You will be subject to the destination website's privacy policy when you follow the link.

Dysarthria (difficulty speaking)

Dysarthria is where you have difficulty speaking because the muscles you use for speech are weak. It can be caused by conditions that damage your brain or nerves and some medicines. Speech and language therapy can help.

Immediate action required: Call 999 if:

• somebody's face droops on 1 side (the mouth or eye may have drooped)
• a person cannot lift up both arms and keep them there
• a person has difficulty speaking (speech may be slurred or garbled)

These can be signs of a stroke, which is a medical emergency. The symptoms of a stroke usually come on suddenly.

Check if it's dysarthria

The main symptom of dysarthria is unclear speech. This can make it difficult for you to make yourself understood.

Your speech may only be slightly unclear, or you may not be able to speak clearly at all.

Other symptoms include:

• difficulty moving your mouth, tongue or lips
• slurred or slow speech
• difficulty controlling the volume of your voice, making you talk too loudly or quietly
• a change in your voice, making it nasal, strained or monotone
• hesitating a lot when talking, or speaking in short bursts instead of full sentences

Being stressed or tired may make your symptoms worse.

Dysarthria is not the same as dysphasia, although you can have both conditions at the same time. Dysphasia, also known as aphasia , is where you have difficulty understanding words or putting them together in a sentence.

Non-urgent advice: See a GP if:

• you've noticed gradual changes to your or your child's speech and you're worried

They'll examine you and may refer you to a specialist for further tests.

Causes of dysarthria

Dysarthria is usually caused by damage to the brain or conditions that affect the nervous system. It can happen at any age.

Common causes include:

• stroke , severe head injury and brain tumours
• Parkinson's disease , multiple sclerosis and motor neurone disease
• cerebral palsy and Down's syndrome

It can also be a side effect of certain medicines, such as some medicines to treat epilepsy.

Treatment for dysarthria

If you have dysarthria, you'll usually be referred to a speech and language therapist. They'll offer therapy to help your speech and communication.

The therapy you're offered will be different depending on the cause of your dysarthria and how severe it is.

Some people may find therapy does not help their symptoms, or their speech may get worse as their condition progresses. Their therapy may focus on helping communication in other ways.

Speech and language therapy may include:

• exercises to strengthen the muscles used for speech
• strategies to make your speech easier to understand, such as slowing down when you're talking
• using communication aids, such as an alphabet board or a voice amplifier

Find out more

• Headway: communication problems after brain injury
• Stroke Association: communication tools

Page last reviewed: 17 February 2023 Next review due: 17 February 2026

How Does Anxiety Affect Your Vision?

In this article

Did you know anxiety and vision problems are related? Research shows that people with vision issues are prone to anxiety due to the loneliness, social isolation, worry, and fear that comes with it. 1  

The reverse is also true. According to The National Center for Biotechnology Information (NCBI), anxiety and mental stress can affect your vision. 

When you’re anxious about something, your fight or flight response is activated, and your body produces the hormones adrenaline and cortisol to prepare you for “potential threats.” 

Excessive release of these stress hormones can cause systemic imbalances, causing symptoms like:

• Trouble focusing
• Trouble sleeping (insomnia)
• Being easily fatigued
• Restlessness (feeling wound up or on edge)
• Headaches, muscle aches, and unexplained pains
• Increased irritability (feeling of agitation)
• Dizziness/ vertigo (feeling of imbalance and spinning)
• Panic attacks (trembling, etc.)
• Increased blood pressure/heartbeat
• A transient ischemic attack (TIA) or stroke

Visual Signs of Anxiety

The visual signs of anxiety occur alongside or as a consequence of other anxiety symptoms. They may also vary from person to person. They include: 

• Sudden blurred vision. Loss of sharpness in focusing, making objects appear hazy. This is common when someone is feeling dizzy.
• Eye strain. Anxiety causes the release of adrenaline which causes your pupils to dilate (increase in size). Frequent anxiety causes constant dilation of the pupils , which can eventually result in stress-induced eye strain .
• Eye twitching. The result of eye strain and tightening of eye muscles due to fatigue or insomnia.
• Visual irregularities. People with anxiety often report seeing stars, shadows, flashing lights, and floaters (rare).
• Light sensitivity (photophobia). Sleep deprivation may increase your eye’s sensitivity to light, accompanied by eye twitching .
• Glaucoma (increased eye pressure). Severe sleep deprivation due to anxiety can lead to glaucoma (increased eye pressure).
• Tunnel vision (loss of peripheral vision). Anxiety activates the stress response (flight or fight), which causes a reduction in peripheral vision to focus your attention solely on the impending “danger.” 2 Repeated panic attacks can affect your eyes over time.
• Dry eyes. Stress-induced eye strain is often accompanied by dry eyes and eye fatigue.

Some symptoms, such as light sensitivity and loss of peripheral vision, are likely to manifest during severe anxiety episodes. Other symptoms, like eye strain and twitching, are more likely associated with the long-term effects of excess anxiety.

Can Stress Cause Vision Problems?

Mental distress is one of the leading causes of vision loss. Evidence of this dates back to over 3,000 years ago, based on Sushruta Samhita , a book by a famous traditional Indian doctor practicing Ayurveda medicine. 6 According to Sushruta, there are many causes of vision loss:

• Improper sleeping habits  
• Continuous weeping
• Excessive anger
• Grief/sorrow
• Stress, suffering, pain, and mental exhaustion
• Suppression of tears (holding back from crying)

These are signs of bodily or emotional stress. Modern medicine agrees with Susruta’s literature. According to eye experts, stress can affect your vision through visual distortions or even vision loss (blindness). 

When you’re stressed, your body produces high levels of cortisol and adrenaline, which potentially cause an increase in eye pressure and blurry vision. People with chronic stress may experience regular eye strain accompanied by headaches.

Fortunately, most stress-related vision problems are mild and temporary and will disappear once your stress eases.

A serious eye condition caused by stress is Central Serous Chorioretinopathy (CSCR). It’s characterized by fluid accumulation under the retina. 7 The retina is the light-sensitive part of the eye that receives light signals and sends them to the brain for interpretation. 

CSCR damages the retinal pigment epithelium (RPE), a layer involved in the renewal of visual cells. This can lead to blindness.

Common Visual Symptoms of Stress

Signs of stress-related eye problems include:

• Blurry vision
• Sensitivity to bright light (photophobia)
• Sore eye muscles
• Excessive tearing
• Eye floaters
• Eye twitching
• Double vision (Diplopia)
• Halos and rings
• Unusual pulsing
• Narrowed vision or tunnel vision

Although anxiety and stress (depression) are two different things, they’re interrelated and have nearly identical symptoms.

Can Anxiety Cause Blindness?

Although it’s rare for mild anxiety to cause complete vision loss, frequent extreme anxiety can increase your body’s adrenaline and cortisol levels, which can cause glaucoma (increased eye pressure) or optic neuropathy. 8 Both conditions can lead to blindness. 

Can Anxiety Raise Eye Pressure?

If your anxiety disorder is accompanied by severe insomnia, repetitive eye strain, or dry eyes, you may experience increased eye pressure, also called glaucoma. 3 Anxiety may also worsen existing glaucoma . 4  

Symptoms of glaucoma include:

• Light sensitivity
• Double vision
• Nausea/vomiting
• Blurred vision
• Halos or rings around lights

Anxiety causes an increased heart rate. According to research, people with high pulse pressure have an increased risk for high-tension open-angle glaucoma. 5

Tips to Keep Your Eyes Healthy

As you have seen, stress and anxiety can affect your vision. Fortunately, you can do something to keep your eyes safe from stress-related problems or reduce the progression of vision loss. The best way to avoid stress and anxiety is by taking care of yourself and reducing worry. Do the following:

• Add physical activity to your day. Exercise lowers your risk of developing health problems that can affect your vision. It also elevates your mood and reduces anxiety and stress.
• Eat a balanced diet. Healthy foods improve your mood and immune system, lowering the risk of diabetic retinopathy, a leading cause of vision loss among working-age adults. 10
• Share with a therapist. If your mental stress and anxiety are overwhelming, talk to a mental health professional. 
• Avoid smoking. Research shows that smoking increases anxiety and stress, whose symptoms can affect your eyes. 11 The smoke itself can cause eye diseases such as cataracts and AMD.
• Manage chronic conditions. Long-term health conditions such as heart disease, cancer, and diabetes can elevate your stress and cause vision problems. 
• Avoid extended screen time. Looking at your computer screen for several hours can elevate your stress levels, cause eye strain , and affect your vision over time (near point visual stress (NPVS).
• Try meditation. Meditation programs such as Eye Yoga can help ease eye strain.
• Get enough sleep. Adequate sleep enables your brain and eyes to rest and refresh for new activities. This improves vision.
• Try to socialize. Talking to loved ones and friends through video calls or chats can help reduce stress symptoms and improve your vision during stressful moments.

When to See A Doctor

Visual symptoms of stress should disappear once your stress or anxiety calms. However, seek your doctor’s advice if you notice persistent changes to your vision. This will help them rule out or treat any underlying conditions.

Seek medical attention if you experience blurred vision accompanied by the following:

• Severe headache
• Slurred speech
• Facial muscle drooping
• Loss of muscle control (on one side)
• Vision loss

Treatment Options

Below are treatment options for stress-related vision problems:

• Vision therapy. Regular eye exercises to ease discomfort and improve visual skills and abilities in affected eyes. Your vision therapist may use training glasses/lenses, prisms, filters, electronic devices, or balance boards to perform the therapy. 
• Behavioral therapy. Talking to a behavioral therapist can help you identify ways of managing your stress and anxiety. Once those improve, your affected vision will also improve.
• Medications. Your doctor may prescribe medications, such as Benzodiazepines (Valium, Xanax, etc.), to offer instant relief from stress. They could also prescribe lubricating eye drops or artificial tears for managing stress-related dry eyes.

Other Factors That Can Affect Vision

Besides stress and anxiety disorders, other factors that can affect your vision include: 9

• Lifestyle habits, such as a poor diet
• Behavioral factors, such as smoking
• Eye trauma or injury
• Ultraviolet (UV) ray exposure
• Eye diseases, such as cataracts, diabetic retinopathy , Age-Related Macular Degeneration (AMD) , etc.
• Eye infections, such as conjunctivitis or infectious keratitis
• Poor eye surgery

According to The National Center for Biotechnology Information (NCBI), anxiety and mental stress can affect your vision due to excess adrenal and cortisol release. 

The visual signs of anxiety and stress occur alongside or are a consequence of severe symptoms, such as restlessness, trouble sleeping, and increased blood pressure, among others.

These signs include blurry vision, eye floaters, excess tearing, dry eyes, eye strain, and sensitivity to light, among others.

You can avoid stress and keep your eyes healthy by maintaining a healthy lifestyle and involving a therapist if your vision problems persist.

Related Articles

Dry Eye Treatment: Effective Remedies & Solutions

by Vince Ayaga

Can Depression Change People's Vision?

Medically Reviewed by Dr. Melody Huang, O.D.

Pediatric Vision Care

How Does Diabetes Affect the Eyes?

What Are the 3 Types of Eye Doctors?

• Demmin and Silverstein. “ Visual Impairment and Mental Health: Unmet Needs and Treatment Options ,” National Center for Biotechnology Information (NCBI), 2020.
• National Institute of Health (NIH). “ Anxiety ,” www.ncbi.nlm.nih.gov, 2022. 
• National Eye Institute.“ NEI-funded research suggests repetitive strain from eye movement may play a role in glaucoma ,” www.nei.nih.gov, 2018.
• Gillmann et al., “ Acute emotional stress as a trigger for intraocular pressure elevation in Glaucoma ,” BMC Ophthalmology, 2019.
• Hulsman C. et al., “ Blood Pressure, Arterial Stiffness, and Open-angle Glaucoma ,” American Medical Association, 2007.
• Sabel et al., “ Mental stress as consequence and cause of vision loss: the dawn of psychosomatic ophthalmology for preventive and personalized medicine ,” EPMA Journal, 2018.
• Sesar et al., “ Personality Traits, Stress, and Emotional Intelligence Associated with Central Serous Chorioretinopathy ,” National Center for Biotechnology Information (NCBI), 2021.
• American Institute of Stress. “ How Stress Affects Your Vision ,” www.stress.org, 2022.
• CDC. “ Social Determinants of Health, Health Equity, and Vision Loss ,” www.cdc.gov, 2021.
• CDC. “ Diabetes and Vision Loss ,” www.cdc.gov, 2021
• “Perceived stress and smoking-related behaviors and symptomatology in male and female smokers ” National Center for Biotechnology Information,2016.

• Find a Lasik Surgeon Near You
• Find Optometrist Near You
• Contact Lenses

Other Links

• Advertise With Us
• Privacy Policy
• Listen to the Podcast

Social Links

Fastest Nurse Insight Engine

• MEDICAL ASSISSTANT
• Abdominal Key
• Anesthesia Key
• Basicmedical Key
• Otolaryngology & Ophthalmology
• Musculoskeletal Key
• Obstetric, Gynecology and Pediatric
• Oncology & Hematology
• Plastic Surgery & Dermatology
• Clinical Dentistry
• Radiology Key
• Thoracic Key
• Veterinary Medicine
• Gold Membership

37. Hearing, speech, and vision problems

CHAPTER 37 Hearing, speech, and vision problems Objectives •  Define the key terms and key abbreviations listed in this chapter. •  Describe the common ear disorders. •  Describe how to communicate with persons who have hearing loss. •  Explain the purpose of a hearing aid. •  Describe how to care for hearing aids. •  Describe the common speech disorders. •  Explain how to communicate with speech-impaired persons. •  Describe the common eye disorders. •  Explain how to assist persons who are visually impaired or blind. •  Explain how to protect an ocular prosthesis from loss or damage. •  Perform the procedure described in this chapter. •  Explain how to promote quality of life. Key terms aphasia  The total or partial loss (a) of the ability to use or understand language (phasia); a language disorder resulting from damage to parts of the brain responsible for language blindness  The absence of sight braille  A touch reading and writing system that uses raised dots for each letter of the alphabet; the first 10 letters also represent the numbers 0 through 9 Broca’s aphasia  See “ expressive aphasia ” cerumen  Earwax deafness  Hearing loss in which it is impossible for the person to understand speech through hearing alone expressive aphasia  Difficulty expressing or sending out thoughts; motor aphasia, Broca’s aphasia expressive-receptive aphasia  Difficulty expressing or sending out thoughts and difficulty understanding language; global aphasia, mixed aphasia global aphasia  See “ expressive-receptive aphasia ” hearing loss  Not being able to hear the normal range of sounds associated with normal hearing low vision  Eyesight that cannot be corrected with eyeglasses, contact lenses, drugs, or surgery mixed aphasia  See “ expressive-receptive aphasia ” motor aphasia  See “ expressive aphasia ” receptive aphasia  Difficulty understanding language; Wernicke’s aphasia tinnitus  A ringing, roaring, hissing, or buzzing sound in the ears or head vertigo  Dizziness Wernicke’s aphasia  See “ receptive aphasia ” KEY ABBREVIATIONS AFB American Foundation for the Blind AMD Age-related macular degeneration ASL American Sign Language Hearing, speech, and vision allow communication, learning, and moving about. They are important for self-care, work, and most activities. They also are important for safety and security needs. For example, you see dark clouds and hear tornado warning sirens. You know to seek shelter. With speech, you can alert others. Many people have some degree of hearing or vision loss. Common causes are birth defects, accidents, infections, diseases, and aging. Ear disorders The ear functions in hearing and balance. To review the structures and functions of the ear, see Chapter 9 . Otitis media Otitis media is infection (itis) of the middle (media) ear (ot). It often begins with infections that cause sore throats, colds, or other respiratory infections that spread to the middle ear. Viruses and bacteria are causes. Otitis media is acute or chronic. Chronic otitis media can damage the tympanic membrane (eardrum) or the ossicles ( Chapter 9 ). These structures are needed for hearing. Permanent hearing loss can occur. Fluid builds up in the ear. Pain (earache) and hearing loss occur. So do fever and tinnitus. Tinnitus is a ringing, roaring, hissing, or buzzing sound in the ears or head. An untreated infection can travel to the brain and other structures in the head. The doctor orders antibiotics, drugs for pain relief, or drugs to relieve congestion. See Residents With Dementia: Otitis Media. RESIDENTS WITH DEMENTIA Otitis Media Some persons with dementia cannot tell you about pain or when something is wrong. Be alert for behavior changes. Report the following to the nurse. They may signal otitis media: •  Unusual irritability •  Problems sleeping •  Tugging or pulling at one or both ears •  Fever •  Fluid draining from the ear •  Balance problems •  Signs of hearing problems ( p. 580 ) Meniere’s disease Meniere’s disease involves the inner ear. It is a common cause of hearing loss. Usually one ear is affected. Symptoms include: •  Vertigo (dizziness) •  Tinnitus •  Hearing loss •  Pain or pressure in the affected ear With Meniere’s disease, there is increased fluid in the inner ear. The increased fluid causes swelling and pressure in the inner ear. Symptoms occur suddenly. They can occur daily or just once a year. An attack can last several hours. An attack usually involves vertigo, tinnitus, and hearing loss. Vertigo causes whirling and spinning sensations. The dizziness causes severe nausea and vomiting. Drugs, fluid restriction, a low-salt diet, and no alcohol or caffeine decrease fluid in the inner ear. Safety is needed during vertigo. The person must lie down. Falls are prevented. Bed rails are used according to the care plan. The person’s head is kept still. The person avoids turning the head. To talk to the person, stand directly in front of him or her. When movement is necessary, move the person slowly. Sudden movements are avoided. So are bright or glaring lights. Assist with walking. The person should not walk alone in case vertigo occurs. Hearing loss Hearing loss is not being able to hear the normal range of sounds associated with normal hearing. Losses are mild to severe. Deafness is the most severe form. Deafness is hearing loss in which it is impossible for the person to understand speech through hearing alone. Hearing loss occurs in all age-groups. According to the National Institute on Deafness and Other Communication Disorders (NIDCD), about one third (33%) of Americans between ages 65 and 74 have hearing problems. About half (50%) of persons age 75 years and older have hearing loss. Hearing loss is more common in men than in women. Common causes of hearing loss are: •  Damage to the outer, middle, or inner ear •  Damage to the auditory nerve Risk factors that can damage ear structures include: •  Aging •  Exposure to very loud sounds and noises—job-related noises, loud music, loud engines from vehicles, shooting firearms •  Drugs—antibiotics, too much aspirin •  Infections •  Reduced blood flow to the ear caused by high blood pressure, heart and vascular diseases, and diabetes •  Stroke •  Head injuries •  Tumors •  Heredity •  Birth defects Temporary hearing loss can occur from earwax (cerumen). Hearing improves after the earwax is removed. Clear speech, responding to others, safety, and awareness of surroundings require hearing. Many people deny hearing problems. They relate hearing loss to aging. See Focus on Communication: Hearing Loss. FOCUS ON COMMUNICATION Hearing Loss The National Association of the Deaf (NAD) uses the terms deaf and hard-of-hearing to describe persons with hearing loss. Do not use the terms “deaf and dumb,” “deaf-mute,” or “hearing-impaired.” Such terms offend persons who are deaf or hard-of-hearing. See Promoting Safety and Comfort: Hearing Loss. PROMOTING SAFETY AND COMFORT Hearing Loss Safety Do not try to remove earwax. This is done by a doctor or a nurse. Do not insert anything, including cotton swabs, into the ear. Effects on the person A person may not notice gradual hearing loss. Others may see changes in the person’s behavior or attitude. They may not relate the changes to hearing loss. Obvious signs and symptoms of hearing loss include: •  Speaking too loudly •  Leaning forward to hear •  Turning and cupping the better ear toward the speaker •  Answering questions or responding inappropriately •  Asking for words to be repeated •  Asking others to speak louder or to speak more slowly and clearly •  Having trouble hearing over the phone •  Finding it hard to follow conversations when two or more people are talking •  Turning up the TV, radio, or music volume so loud that others complain •  Thinking that others are mumbling or slurring words •  Having problems understanding women and children Psychological and social changes are less obvious. People may give wrong answers or responses. Therefore they tend to shun social events to avoid embarrassment. Often they feel lonely, bored, and left out. Only parts of conversations are heard. They may become suspicious. They think others are talking about them or are talking softly on purpose. Some control conversations to avoid responding or being labeled “senile” because of poor answers. Straining and working hard to hear can cause fatigue, frustration, and irritability. Hearing is needed for speech. How you pronounce words and voice volume depend on how you hear yourself. Hearing loss may result in slurred speech. Words may be pronounced wrong. Some have monotone speech or drop word endings. It may be hard to understand what the person says. Do not assume or pretend that you understand what the person says. Otherwise, serious problems can result. See “ Speech Disorders” on p. 583 . Communication Persons with hearing loss may wear hearing aids or lip-read (speech-read). They watch facial expressions, gestures, and body language. Some people learn American Sign Language (ASL) ( Figs. 37-1 and 37-2 ). ASL uses signs made with the hands and other movements such as facial expressions, gestures, and postures. To promote communication, practice the measures in Box 37-1 , p. 582. (Different sign languages are used in different countries and regions. For example, British Sign Language is different from ASL.) Fig. 37-1 Manual alphabet. (Courtesy National Association of the Deaf, Silver Spring, Md.) Fig. 37-2 American Sign Language examples. Box 37-1 Measures to Promote Hearing The environment •  Reduce or eliminate background noises. Turn off radios, stereos, music players, TVs, air conditioners, fans, and so on. •  Provide a quiet place to talk. •  Have the person sit in small groups or where he or she can hear best. The person •  Have the person wear his or her hearing aid. It must be turned on and working. •  Have the person wear needed eyeglasses or contact lenses. The person needs to see your face for lip-reading (speech-reading). You •  Gain attention. Alert the person to your presence. Raise an arm or hand, or lightly touch the person’s arm. Do not startle or approach the person from behind. •  Position yourself at the person’s level. If the person is sitting, you sit. If the person is standing, you stand. •  Face the person when speaking. Do not turn or walk away while you are talking. Do not talk to the person from the doorway or another room. •  Stand or sit in good light. Shadows and glares affect the person’s ability to see your face clearly. •  Speak clearly, distinctly, and slowly. •  Speak in a normal tone of voice. Do not shout. •  Adjust the pitch of your voice as needed. Ask the person if he or she can hear you better: •  If the person does not wear a hearing aid, lower the pitch if you are a female. Women’s voices are higher-pitched and harder to hear than lower-pitched male voices. •  If the person wears a hearing aid, raise the pitch slightly. •  Do not cover your mouth, smoke, eat, or chew gum while talking. Mouth movements are affected. •  Keep your hands away from your face. The person must be able to clearly see your face. •  Stand or sit on the side of the better ear. •  State the topic of conversation first. •  Tell the person when you are changing the subject. State the new subject of conversation. •  Use short sentences and simple words. •  Use gestures and facial expressions to give useful clues. •  Write out important names and words. •  Say things in another way if the person does not seem to understand. •  Keep conversations and discussions short. This avoids tiring the person. •  Repeat and rephrase statements as needed. •  Be alert to messages sent by your facial expressions, gestures, and body language. Some people have hearing assistance dogs (hearing dogs). The dog alerts the person to sounds. Phones, doorbells, smoke detectors, alarm clocks, sirens, and on-coming cars are examples. Hearing aids Hearing aids are electronic devices that fit inside or behind the ear ( Fig. 37-3 ). They make sounds louder. They do not correct, restore, or cure hearing problems. Hearing ability does not improve. The person hears better because the device makes sounds louder. Background noise and speech are louder. The measures in Box 37-1 apply. Fig. 37-3 A hearing aid. (Courtesy Siemens Hearing Instruments, Inc., Piscataway, NJ.) Hearing aids are battery-operated. Sometimes they do not seem to work properly. Try these simple measures: •  Check if the hearing aid is on. It has an on and off switch. •  Check the battery position. •  Insert a new battery if needed. •  Clean the hearing aid. Follow the nurse’s directions and the manufacturer’s instructions. Hearing aids are turned off when not in use. And the battery is removed. These measures help prolong battery life. The person should not use hair spray or other hair care products while wearing a hearing aid. They can damage the device. Hearing aids are costly. Handle and care for them properly. When not in the person’s ear, store a hearing aid in its case. Place the case in the top drawer of the bedside stand. Report lost or damaged hearing aids to the nurse at once. Other hearing devices Other devices can help the person with hearing loss. They include: •  Telephone amplifying devices. Special telephone receivers make sounds louder. Some phones work with hearing aids. •  TV and radio listening systems. These can be used with or without hearing aids. The person does not have to turn the TV or radio volume up high. Speech disorders Speech is used to communicate with others. Speech disorders result in impaired or ineffective oral communication. Hearing loss, developmental disabilities ( Chapter 45 ), and brain injury are common causes. The following are common problems. •  Aphasia. See “ Aphasia .” •  Apraxia means not (a) to act, do, or perform (praxia) . The person with apraxia of speech cannot use the speech muscles to produce understandable speech. The person understands speech and knows what to say. However, the brain cannot coordinate the speech muscles to make the words. Apraxia is caused by damage to the motor speech area in the brain. •  Dysarthria means difficult or poor (dys) speech (arthria). It is caused by damage to the nervous system. Mouth and face muscles are affected. Slurred speech, speaking slowly or softly, hoarseness, and drooling are other problems that can occur. To communicate with the speech-impaired person, practice the measures in Box 37-2 . Box 37-2 Measures to Communicate With the Speech-Impaired Person The person •  Ask the person to repeat or rephrase statements if necessary. •  Repeat what the person has said. Ask if your understanding is correct. •  Ask the person to write down key words or the message. •  Ask the person to point, gesture, or draw to communicate key words. You •  Follow the care plan. A consistent approach is needed. •  Provide a calm, quiet setting. Turn off the TV, radio, music, and other distractions. •  Include the person in conversations. •  Listen, and give the person your full attention. •  Use short, simple sentences. •  Repeat what you are saying as needed. •  Write down key words as needed. •  Speak to the person in a normal, adult tone. Do not treat or talk to the adult in a babyish or child-like way. •  Ask the person questions to which you know the answers. This helps you learn how the person speaks. •  Allow the person plenty of time to talk. •  Determine the topic being discussed. This helps you understand main points. Watch the person’s lip movements. •  Watch facial expressions, gestures, and body language. They give clues about what is being said. •  Do not correct the person’s speech. See Focus on Rehabilitation: Speech Disorders. FOCUS ON REHABILITATION Speech Disorders Some persons need speech rehabilitation. The goal is to improve the person’s ability to communicate. A speech-language pathologist and other health team members help the person: •  Improve affected language skills •  Use remaining abilities •  Restore language abilities to the extent possible •  Learn other methods of communicating •  Strengthen the muscles of speech The amount of improvement possible depends on many factors. They include the cause, amount, and area of brain damage and the person’s age and health. The person’s willingness and ability to learn are other factors. Aphasia Aphasia is the total or partial loss (a) of the ability to use or understand language (phasia). Aphasia is a language disorder. It results from damage to parts of the brain responsible for language. Stroke, head injury, brain infections, and cancer are common causes. Most people who have aphasia are middle-aged adults and older. Expressive aphasia (motor aphasia, Broca’s aphasia) relates to difficulty expressing or sending out thoughts. Thinking is clear. The person knows what to say but has difficulty or cannot speak the words. There are problems speaking, spelling, counting, gesturing, or writing. The person may: •  Omit small words such as “is,” “and,” “of,” and “the.” •  Speak in single words or short sentences. For example, “Walk dog” can mean “I will take the dog for a walk” or “You take the dog for a walk.” •  Put words in the wrong order. Instead of “bathroom,” the person may say “room bath.” •  Think one thing but say another. The person may want food but asks for a book. •  Call people by the wrong names. •  Make up words. •  Produce sounds and no words. •  Cry or swear for no reason.

Share this:

• Click to share on Twitter (Opens in new window)
• Click to share on Facebook (Opens in new window)

Related posts:

• 10. The older person
• 29. Respiratory support and therapies
• 28. Oxygen needs
• 35. Wound care

Stay updated, free articles. Join our Telegram channel

Comments are closed for this page.

Full access? Get Clinical Tree

An official website of the United States government

The .gov means it’s official. Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

The site is secure. The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

• Publications
• Account settings

Preview improvements coming to the PMC website in October 2024. Learn More or Try it out now .

• Advanced Search
• Journal List
• Eur J Med Res
• PMC10364432

Speech deficits in multiple sclerosis: a narrative review of the existing literature

Panagiotis plotas.

1 Department of Speech and Language Therapy, School of Health Rehabilitation Sciences, University of Patras, Patras, Greece

2 Laboratory of Primary Health Care, School of Health Rehabilitation Sciences, University of Patras, Patras, Greece

Vasiliki Nanousi

Anastasios kantanis, eirini tsiamaki.

3 Department of Neurology, Medical School, University of Patras, Patras, Greece

Angelos Papadopoulos

Angeliki tsapara, aggeliki glyka, efraimia mani, fay roumelioti, georgia strataki, georgia fragkou, konstantina mavreli, natalia ziouli, nikolaos trimmis, associated data.

Not applicable.

Multiple sclerosis (MS) is a chronic inflammatory and demyelinating autoimmune disease. MS patients deal with motor and sensory impairments, visual disabilities, cognitive disorders, and speech and language deficits. The study aimed to record, enhance, update, and delve into our present comprehension of speech deficits observed in patients with MS and the methodology (assessment tools) studies followed. The method used was a search of the literature through the databases for May 2015 until June 2022. The reviewed studies offer insight into speech impairments most exhibited by MS patients. Patients with MS face numerous communication changes concerning the phonation system (changes observed concerning speech rate, long pause duration) and lower volume. Moreover, the articulation system was affected by the lack of muscle synchronization and inaccurate pronunciations, mainly of vowels. Finally, there are changes regarding prosody (MS patients exhibited monotonous speech). Findings indicated that MS patients experience communication changes across various domains. Based on the reviewed studies, we concluded that the speech system of MS patients is impaired to some extent, and the patients face many changes that impact their conversational ability and the production of slower and inaccurate speech. These changes can affect MS patients’ quality of life.

Introduction

Multiple sclerosis (MS) is a chronic, progressive, autoimmune disease of the central nervous system, ‘characterized by inflammation, demyelination, followed by neurodegeneration’ [ 1 ]. MS is caused by damage to the myelin sheath, i.e., the protective covering of nerve fibers (axons) disrupting in that way the transmission of the nerve impulses to and from the central nervous system leading to specific clinical symptoms [ 2 ]. It also damages the nerve cell bodies (and their axons) in the brain, spinal cord and optic nerves affecting the transmission of visual information from the eye to the brain [ 3 ]. MS has traditionally been characterized as a persistent inflammatory ailment affecting the central nervous system [ 4 ]. This results in significant focal lesions in the white matter of the brain and spinal cord, marked by primary demyelination and varying degrees of axonal loss [ 4 ]. The presence of a dense glial scar in long-standing established lesions is associated with a profound astroglia reaction in the brain of individuals with MS, which in turn is linked to demyelination and neurodegeneration [ 4 – 6 ]. As the disease progresses the cerebral cortex shrinks leading to cortical atrophy [ 5 , 6 ]. In addition, neuronal impairment has the potential to impact various bodily functions such as vision, sensation, coordination, movement, and bladder or bowel control [ 7 ]. This can lead to a range of neurogenic lower urinary tract symptoms in individuals with multiple sclerosis (MS), which have been reported to significantly impact their quality of life [ 8 , 9 ]. MS can be diagnosed at any age; it most commonly manifests itself between ages 20 to 40, while the average age of onset is 30 years [ 10 ]. MS affects women twice as much as men [ 11 ]. MS etiology is still unclear, but it seems to be a disorder with great heterogeneity both among patients as well as within the same patient [ 12 ]; it is multifactorial attributed to both environmental and genetic factors [ 13 ].

There is a great variety of signs and symptoms in MS and many patterns have been identified: benign; a relapsing–remitting course; a secondary progressive type; and a primary progressive type [ 14 ]. In MS patients, the initial neurological signs and symptoms are subclinical, lasting for at least 24 h. This clinical presentation is known as clinically isolated syndrome (CIS) [ 14 ]. MS patients exhibit a range of symptoms reflecting multifocal lesions within the central nervous system affecting the motor, sensory, and visual systems. Thus, MS has a great impact on quality of life, as patients suffer from fatigue and mental difficulties [ 15 ], emotional distress [ 16 ], including depression, anxiety, negative mood, and trauma symptoms [ 17 ], alongside the sensory and motor limitations. Impairment of the motor system can subsequently affect the quality of communication [ 18 ].

The literature indicated that a large proportion of the MS population is impaired on standard neuropsychological tests, including verbal skills [ 18 , 19 ]. Regarding the neuroanatomical pathophysiology of MS, cortical and subcortical brain structures have been identified to play a crucial role in the adjustment and coordination of the movement aspects of speech [ 20 ]. Communication is disrupted by the occurrence of motor speech disorders (dysarthria) that potentially affects all speech subsystems including, respiration, phonation, resonance, articulation, and prosody, along with impairments in receptive and expressive language [ 21 ]. Dysarthria is a prevalent motor speech disorder observed in individuals with MS, which restricts their communicative capacity in social situations and consequently impacts their overall quality of life [ 22 , 23 ]. According to existing literature [ 24 ], individuals with MS may exhibit three distinct types of dysarthria, namely spastic dysarthria, ataxic dysarthria, and mixed dysarthria. Unique patterns of speech symptoms characterize these types of dysarthria. Nevertheless, it is worth noting that dysarthria is not the sole speech impairment that can be observed in the speech of individuals with multiple sclerosis. [ 24 ]. In addition, in MS, the lack of voluntary coordination of muscle movements is referred to as ataxia, which can cause speech problems [ 25 ]. Many difficulties concerning other domains such as voice, fluency and rate of speech are also noted which in turn have a significant effect on patients’ everyday communication [ 26 ]. The crucial responsibility of speech and language pathologists is to not only recognize and tackle speech impairments, but also to assist individuals in engaging in their daily routines by acquiring and implementing compensatory techniques to mitigate these challenges and enhance their overall well-being. Moreover, a recent meta-analysis has indicated that respiratory muscle training can enhance lung volumes and respiratory muscle strength in neuromuscular conditions such as multiple sclerosis (MS)[ 27 ].

Assessment tools

Given that the preliminary indications of the ailment often become apparent during the initial stages of adulthood, it is imperative to conduct neurological and neuropsychological assessments at an early stage of the diagnostic procedure for individuals who have been diagnosed with MS or are suspected to have MS. In this field, comprehensive neuropsychological test like the Minimal Assessment of Cognitive Function in MS [ 28 ], the Brief International Cognitive Assessment for MS [ 29 ] and the shortened version of Rao's Brief Repeatable Battery [ 30 ] attempting to cover the cognitive domains most commonly affected by MS. Moreover, in studies with MS patients [ 31 , 32 ] the National Adult Reading Test [ 33 , 34 ] Second Edition was used. The National Adult Reading Test is a test of premorbid intellectual functioning [ 35 ]. The Pyramids and Palm Trees Test was created in 1992 by Howard and Patterson [ 36 ] to measure the capacity to access detailed semantic information about words and objects and was used by researchers in patients with MS [ 31 , 37 ].

Furthermore, The Expanded Disability Status Scale (EDSS) [ 38 ] is the most widely used instrument for evaluating disability in MS patients [ 39 ].

The evaluation of speech and language parameters, particularly verbal learning, has been conducted using various assessment tools in studies with MS patients. One such tool is the Rey Auditory Verbal Learning Test [ 40 , 41 ]. Furthermore, in 2020 developed the Communication and Language Assessment Questionnaire for persons with Multiple Sclerosis [ 42 ], a reliable and valid tool that assesses self-perceived communication and language function in MS [ 42 ]. Furthermore, the Addenbrooke’s Cognitive Examination Revised [ 43 ] was used in studies for MS patients [ 44 , 45 ] and contains 5 domains, between them one fluency domain and one language domain [ 43 ].

More specifically, to evaluate speech in MS patients, studies used many tools for that scope such as (a) the Assessment of Intelligibility of Dysarthric Speech Sentence Intelligibility Task [ 46 , 47 ], (b) the speech pathology-specific questionnaire for patients with multiple sclerosis [ 48 , 49 ], (c) the Dysphonia Severity Index [ 50 ], the GRBAS scale [ 51 – 53 ], the Voice Handicap Index, a self-reporting tool [ 54 ], the standardized speech tasks [ 55 , 56 ], the Formant Centralization Ratio [ 57 , 58 ] has been used as an acoustic metric of dysarthric speech. In terms of tongue control and function in MS a study [ 59 ] suggest that the quantitative motor measurement [ 60 ] of tongue function might proof useful efficient method to assess motor dysfunction in MS. To assess ataxia in MS patients, the Scale for the Assessment and Rating of Ataxia was developed [ 25 , 61 ]. Each word is presented individually, and subjects are required to read each aloud [ 35 ]. The aforementioned assessment tools and measures contribute to a comprehensive evaluation of speech (voice, motor control) in individuals with MS, providing valuable insights for diagnosis, monitoring, and treatment planning.

This narrative review aimed to identify, enhance, update, and delve into our present comprehension of the type of speech deficits observed in patients with MS and the methodology (assessment tools) that studies followed that were published from May 2015 to June 2022.

Materials and methods

Α literature search was conducted on the MedLine and Scopus bases in June 2022 with the keywords ‘multiple sclerosis’, ‘speech disorders’, ‘dysarthria’, ‘communication disorders’, ‘phonological disorders’, ‘speech pathology’, ‘anomia’, ‘dysphonia’ and ‘voice problems’. We did not use PRISMA guidelines while conducting our review as it is a narrative review of the existing literature.

The dataset of the current study spanned from May 2015 to June 2022. There were specific eligibility criteria applied for the inclusion of studies in the current review. These were the following: For a study to be included it had to (1) have original data, (2) be conducted on patients with MS who exhibit speech difficulties, (3) focus on speech deficits that patients with MS face, (4) be written and presented in English, and (5) be published from 2015 to 2022. The exclusion criteria were the following: (1) no original data (letters to editor or other reviews were excluded), (2) the study targeted language and cognitive disorders, (3) the study targeted dysphagia, (4) the study targeted treatment methods, and (5) the study was published before 2015. Following database screening, titles and abstracts were reviewed to verify the inclusion criteria. An additional literature search was conducted for related references included in the manuscripts. After duplicates were removed, the suitability of the scanned abstracts was assessed by two independent individuals. Then the full texts were retrieved and read making sure that they met the eligibility criteria applied for this review. Conflicts were resolved after discussion between the authors. Following this, the results of the studies were compiled and presented in two different tables. In the first table, general information and sample characteristics of each study are provided. The second table includes a summary of the results obtained from speech assessments along with the main findings of the studies.

The data sets of the studies reviewed in this paper were presented according to the following variables: type, mean age of the participants, gender, tests used to establish diagnosis and additional details. With regard to results, all studies used control group of healthy participants. Most of studies reported that EDSS was used to establish diagnosis. Furthermore, almost all studies clearly reported that the patients involved were over 18 years of age except from two studies that had no reference that the patients were over 18 years of age. Summary in the studies 281 males and 628 females recruited. Regarding the exclusion criteria, an acute upper airway respiratory infection, patients to be relapse-free for a month at least prior to testing, voice disorders, larynx malignance, no other neurological disorders other than MS, no vision or hearing problems were required. In addition, the inclusion criteria, patients’ ability to fill in questionnaires, a neurologically confirmed diagnosis of MS, symptoms of dysarthria. More information is shown in Table ​ Table1 1 .

Study information and sample characteristics of the articles included in the review

MS multiple sclerosis, RRMS relapsing–remitting multiple sclerosis, PPMS primary progressive multiple sclerosis, SPMS secondary progressive multiple sclerosis, HC healthy control, CIS clinically isolated syndrome, EDSS Expanded Disability Status Score, MSFC Multiple Sclerosis Functional Composite, MRI magnetic resonance imaging

For each study under review, the data obtained from the tests of speech assessment along with the results that were drawn, discussed and the main conclusions are presented in Table ​ Table2 2 .

Summary of the aims, speech assessments, and main findings of the studies

MS multiple sclerosis, DDK diadochokinetic, EDSS Expanded Disability Status Scale, TVF Tongue force variability, SPMS secondary progressive multiple sclerosis, RRMS relapsing–remitting multiple sclerosis, F0 fundamental frequency of a speech signal, tVSA triangular vowel space area, MRI magnetic resonance imaging, MSFC Multiple Sclerosis Functional Composite

Most of studies referred about the effects of MS on motor movement are which includes muscle weakness and what is the reason for muscle weakness, spasticity and loss of coordination and what are the symptoms of MS. As a result, the motor system is impaired and MS patients in their majority also deal with different forms of dysarthria, although not all studies have reached the same conclusion. Dysarthria is considered the primary cause of communication deficit in MS, yet patients with MS present with concurrent cognitive deficits that can interfere with effective communication.

Moreover, the articulation system is impaired. The studies indicated that MS affects the articulators per se and consequently patients’ speech rate. Articulation was analyzed across the studies and was characterized by consonant imprecision, decreased word output rate and slow vowel transitions likely due to slow tongue movements. Findings recognized that MS is a condition that can negatively affect the phonation system. MS patients face dysphonic problems, although there remains to define the severity level and its correlation to other factors. Voice quality was studied in studies [ 51 , 62 ]. The studies that encompassed the documentation of perception primarily adopted a descriptive approach. The majority of multiple sclerosis patients were evaluated as having vocal impairments by speech pathologists. However, respiratory issues and voice impairments were comparatively given less attention and were not thoroughly examined. Furthermore, studies reported on the presence of prosody in patients [ 51 , 63 ]. The speech rate of patients with MS was observed to be reduced and slower, as evidenced by a decrease in the number of syllables per second and a lower production of words per minute when compared to healthy control groups. In relation to tasks involving reading and speech, it was observed through acoustic analysis that individuals with multiple sclerosis exhibited a greater frequency and duration of pauses.

With regard to the main outcome of the studies, dysarthria seems to be a common symptom in MS patients in most of the studies as well as in two studies [ 62 , 69 ]. In the studies [ 62 , 68 ] there was an evaluation of acoustic analysis along with a vowel metric analysis to evaluate speech features and identify significant patterns in voice samples of patients with MS [ 68 ]. The authors considered to better define disordered voices against healthy ones, acoustic analytic approaches have been suggested for implementation of this procedure. In one study [ 70 ] problems with speech extraction were identified. Speech timing was significantly slower for MS patients with dysarthria compared to MS patients without dysarthria. In addition, silent pause durations also significantly differed for MS patients with both dysarthria and cognitive impairment compared to MS patients without either impairment [ 70 ]. Furthermore, in other studies [ 55 , 67 ], Expanded Disability Status Score outcomes were used in support of the general idea that speech impairment is strongly correlated to the level of MS severity. However, in this study [ 51 ] due to the limited number of subjects and due to the limited parameters, that they investigated could not draw any solid conclusions about the level of severity of dysphonia that MS patients exhibited.

Evidence from the studies [ 55 , 61 ] suggests that MS patients demonstrate abnormalities in their speech rate. Specifically, the studies revealed that the pace of speech was comparatively reduced and there was a rise in its variability. Furthermore, it was observed that individuals with multiple sclerosis exhibited an augmentation and extension of the pauses present in their speech. The amplitude of the vocal inflections exhibited a reduced variance, resulting in a uniform and unvarying quality of speech. Cerebellar dysfunction was found to be associated with subclinical voice and tremors.

Finally, the pronunciation of vowels and consonants was inaccurate. A study [ 69 ] found that MS patients exhibited slow articulation during reading and reduced sequence rhythm during rapid syllable repetition, as tests for joint rhythm, auditory speech and sequence rhythm indicated. Furthermore, 2 studies [ 59 , 66 ] addressed the fact that there are motor problems, trembling and problems with the joints in MS patients. It was found that there were reduced ratios of maximal velocity displacement of the lower lips and jaw reduced peak velocities of the tongue. Based on these results it was pointed out that the ability to move the tongue with adequate speed during speech was significantly impaired in patients with MS, providing thus an explanation for their slowed speech rate. Therefore, it was suggested that compensatory strategies are in need during speech treatment in order to ‘maximize speech clarity in the presence of the impaired tongue motor performance’.

The aim of the current literature review was to identify, record, discuss, and delve into the type of speech deficits observed in patients with MS. MS patients can exhibit a range of symptoms in various domains including speech as well. From the aforementioned studies, it is apparent that MS patients face difficulties concerning a number of components of speech including phonation, oral diadochokinesis, articulation, and prosody. These findings have been previously reported in the MS literature and it seems that they are prominent in the majority of patients. Considering the speech-related findings of the studies reviewed above, one of the most commonly identified symptoms of MS was articulation difficulties. In some of the studies reviewed the patients included, exhibited dysarthria [ 63 , 68 , 70 ], while in another study, actual cases of dysphonia were reported [ 51 ]. In other studies, it was also noted that MS patients also face a range of deficiencies regarding speech articulators per se as a result of an impaired motor system [ 59 , 66 ]. However, more research needs to be carried out in order to further address the issue of the way that these deficiencies affect the articulation system of MS patients.

The second most reported deficit in MS patients was impaired phonation and a slow speech rate [ 51 ]. These findings are in line with the MS literature [ 71 ] according to which phonation difficulties such as vocal deficits, breathiness, volume abnormalities, etc., are present in many MS patients. Slow speech rate and long/extended pauses are also commonly observed and described in MS patients [ 69 , 70 ]. Even though respiratory problems and resonatory impairments were less commonly described than other deficits [ 67 ], they still significantly impact patients' everyday lives. However, studies investigating these aspects are scarce, and because they do not follow a standard methodology, no solid conclusions can be drawn. The objective of this review is to enhance and revise our present comprehension of dysarthria in individuals with multiple sclerosis (PwMS),

The current literature review aimed to enhance, update, and delve into our present comprehension of a) the type of speech deficits observed in patients with MS, and b) the methodology (assessment tools) studies followed. In the literature on MS, speech difficulties are notable among patients due to an impairment of the motor system and its underlying anatomical structures. Nonetheless, the main bulk of studies indicates that patients with MS develop dysarthric characteristics. It is important for speech and language therapists working with MS patients to be aware of possible cognitive-linguistic impairments and take this into account when assessing, managing, and intervening. Taking in mind these, there is a need for more studies to be conducted that will apply a more systematic methodological approach and similar inclusion criteria to categorize various speech manifestations better and enhance our understanding of the patterns that may be (or not) associated with the specific clinical subtypes of MS. By doing so better intervention and treatment methods can be discovered and applied that will improve the communicational function, the psychological well-being, and the quality of MS patients’ life.

Future directions

Finally, it would be interesting for future research to systematically investigate possible correlations between the different clinical types of MS and speech deficits. It is essential, though, to stress that to achieve common ground among other studies, similar methodologies and inclusion criteria should be applied. To this end, it is evident that more research must be carried out about the etiology of MS, the neuroanatomical correlates, along with the definition of clinical, cognitive, and linguistic patterns present in each phase to develop better methods of intervention and treatment of MS patients and improve their communication ability and quality of life.

Author contributions

Conceptualization : PP, VN, ET, NT. Literature search: AG, EM, FR, GS, GF, KM, NZ. Data analysis: PP, AK, VN, ET, NT. Writing—review and editing: PP, AP, AT, VN, NT. Supervision: PP, VN, ET, NT. All authors read and approved the final manuscript.

The publication fees of this manuscript have been financed by the Research Council of the University of Patras.

Availability of data and materials

Declarations.

Not applicable (review study).

This study has no conflict of interest.

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Contributor Information

Panagiotis Plotas, Email: rg.sartapu@satolpp .

Vasiliki Nanousi, Email: [email protected] .

Anastasios Kantanis, Email: rg.tenpu@5977401pu .

Eirini Tsiamaki, Email: moc.liamg@ikamaistinirie .

Angelos Papadopoulos, Email: moc.liamg@soluopodapapsolegna .

Angeliki Tsapara, Email: moc.liamg@62stikilegna .

Aggeliki Glyka, Email: [email protected] .

Efraimia Mani, Email: moc.liamg@hnamaimiarfe .

Fay Roumelioti, Email: moc.liamg@uoreeyaf .

Georgia Strataki, Email: moc.liamtoh@89ikatartsg .

Georgia Fragkou, Email: moc.liamtoh@99rfaigroeg .

Konstantina Mavreli, Email: moc.liamg@11ilervamk .

Natalia Ziouli, Email: moc.liamg@eluozailatan .

Nikolaos Trimmis, Email: rg.sartapu@simmirtkcin .