Speech Disorders: Dysarthria, Dysphonia, & MS

Lesions caused by multiple sclerosis (MS) can occur throughout the brain. Speech disorders, including slurring and abnormal rhythm, are a common result.

Occasional speech problems are a common symptom of multiple sclerosis (MS). In fact, many people may not even realize that their speech is affected.

Mild speech disorders may be attributed to other signs, including being tired or fatigued. This is particularly true because mild symptoms may not be present all the time. Common signs of mild speech problems can include:

• mumbling
• speaking in a quiet voice or being often asked to repeat yourself
• speaking slowly
• slurring speech

Beyond these mild speech problems, there are also more severe speech disorders. Dysarthria and dysphonia are two common speech disorders experienced by people with MS. Dysarthria causes difficulty with articulation, and the natural flow of conversation; dysphonia is a voice disorder, resulting in changes to the vocal quality and difficulty in controlling the pitch and volume of the voice.

Prevalence of speech disorders

41-51% of MS Warriors may experience symptoms of dysarthria according to a number of studies reported by the National Multiple Sclerosis Society. These studies have relied on a clinical diagnosis for speech disorders. When self-reporting is used, the prevalence of speech disorders varies.

Study conducted in United States and published in 1985

• Dysarthria prevalence: 23%
• Cohort size: 656 people with MS

Study conducted in Sweden and published in 1994

• Dysarthria prevalence: 44%
• Cohort size: 200 people with MS

Preliminary study conducted in South Africa and published in 2002

• Dysarthria prevalence: 57%
• Cohort size: 30 people with MS

Symptoms of dysarthria

Dysarthria is categorized by slow and/or slurred speech that is often difficult for other people to understand. With dysarthria, there are both vocal symptoms and physical/neuromuscular symptoms. Common symptoms include:

• Slurred speech
• Speaking too rapidly or too slowly
• Speaking too loudly or too quietly
• Raspy, strained speech
• Speaking with an abnormal rhythm or with uneven volume
• Monotone speech
• Jaw-jerking reflexes
• Irregular eye movements

Causes of dysarthria in MS

Dysarthria is caused by a neuromuscular impairment that causes instabilities in the brain that regulate the motor control of the speech system. People with MS can develop lesions throughout the brain, including in the parts of the brain that control speech: the left hemisphere of the cerebrum and the brainstem.

In addition to the impact of lesions, MS also causes weakness, spasticity (stiff muscles), sluggishness, and ataxia (issues with muscle coordination). Ataxia can impact the coordination of the parts of the body needed for speech including the tongue, mandible, lips, vocal cords, soft palate, and diaphragm.

These different mechanisms result in speech disorders having a wide array of symptoms and underlying causes. Because of this, there are 3 types of dysarthria that can result from the location of lesions in the brain. The three types are:

1. Ataxic
   • Caused by generalized or bilateral lesions on the cerebellum
2. Spastic
   • Caused by bilateral lesions of the neuron pathways
3. Mixed
   • Caused by generalized or bilateral lesions of the cerebellum, white matter, spinal cord, and/or the brainstem

Symptoms of dysphonia

In slight contrast to speech disorders, dysphonia is a vocal disorder. Dysphonia is the scientific name for hoarseness or having a hoarse voice.

Symptoms are often changes to the quality of the voice including the voice being:

• Harsh
• Nasally
• Hoarse
• Breathy

Causes of dysphonia

In dysphonia, the larynx (voice box) functions improperly as air moves through it. When functioning properly, the vocal folds are moved toward the midline of the vocal tract by exhaled air. This also causes vibrations of the vocal folds which produce the voice.

There are a number of causes of dysphonia including vocal abuse. If you’ve lost your voice from cheering or yelling, you have experienced dysphonia. This isn’t the only cause, though. Neuromuscular issues, including multiple sclerosis and Parkinson’s disease, growths and polyps, allergens, and systemic diseases can also cause symptoms.

Treatment options for speech disorders

If you believe you are experiencing any signs or symptoms of speech disorders, you should talk through your concerns with your MS Treatment Team.

There are a number of exercise and strengthening exercises that can be used to help people with MS battle:

• Biofeedback
  • A gauge that can measure elements of the voice (including loudness and phrase length) during speech
  • Helps with breath control and breathing patterns during speech
• Exercise the muscles
  • Strengthening the muscles associated with speech including the tongue, mandible, lips, vocal cords, soft palate, and diaphragm improve speech
• Speech therapy
  • Speech pathologists have created programs to help overcome specific symptoms associated with speech disorders