Speech disorders are fairly common in people with MS, affecting an estimated 41% to 51% of MS patients at some point during their illness. Since normal speech depends on a very complex system of nerve signaling in the brain, the specific type of speech problem a person suffers from will depend on where CNS damage or demyelination occurs. For instance, damage in the cerebellum, which is the primary cause of speech problems in MS, often results in a slowing of speech with diminished fluency. If brain areas that control the tongue, lips, soft palate, cheeks, or breathing muscles are affected, speech patterns can become slurred.
Problems with speech in MS may come and go, appearing with exacerbations during which symptoms often worsen then gradually improve. Whether problems progressively worsen depends on the course of the disease for a particular patient.
There are two types of speech disorders that occur in MS, dysarthrias and dysphonias. Speech problems where the motor muscle components of speech are affected are dysarthrias (these typically affect volume control and articulation) while speech problems that affect voice quality are dysphonias.
Two Types of Speech Disorders in MS
- Motor speech disorders
- Impaired volume control: voice becomes too quiet or loud
- Impaired articulation: speech becomes slurred
- Impaired emphasis: speech becomes slowed or broken up with inappropriate pauses, difficulty applying appropriate stress on words or varying pitches and loudness for emphasis
- Disorders of voice quality
- Harshness in voice from spasticity or excess muscle tone
- Impaired pitch control from tremor or spasticity in vocal cords causing pitch breaks or monotone quality
- Hypernasality caused by weakness or lack of coordination in soft palate
- Pitch level irregularities (too high or low) caused by changes in muscle tone
- Breathiness caused by lack of coordination in vocal cords
- Hoarseness caused by vocal cords coming together too tightly and too loosely
What are the treatment options for speech problems?
For people with MS whose speech problems pose a difficulty for everyday communication, treatment options include therapy with a speech/language pathologist. The speech/language pathologist will give you a complete assessment to determine what type or types of problems you have. Then a treatment plan will be formulated to address your specific challenges. Therapy may include exercises for improving strength and coordination in use of your lips, tongue, soft palate, vocal cords, and diaphragm. Different technologies are available for self-monitoring, including recording devices, computer speech analysis software, and an instrument for measuring lung capacity called a spirometer.
Since speech problem in MS happen because of nerve damage and underlying MS-related neuromuscular impairments, including spasticity, tremor, and fatigue, appropriate drug treatment can be combined with speech/language therapy. Medications used to treat spasticity, including Lioresal (baclofen) and Zanaflex (tizanidine), may be useful in cases where spasticity is affecting muscle tone in the vocal cords, tongue, lips, and soft palate or keeping the diaphragm, which supplies support to the voice, from working normally.
Several medications are available for decreasing tremors, which can affect voice quality and vocal muscles directly or indirectly, as well as contribute to fatigue which may also affect speech. These medications include Klonopin (clonazepam), Inderal (propranolol), Mysoline (primidone), and Doriden (glutethimide).
Medications for managing fatigue, which can affect muscular coordination and strength necessary for vocal production, include Symmetrel (amantadine), Provigil (modafinil), and Nuvigil (armodafinil).