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.


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:

  1. Amyotrophic lateral sclerosis (ALS, or Lou Gehrig's disease)
  2. Brain injury
  3. Brain tumor
  4. Cerebral palsy
  5. Guillain-Barre syndrome
  6. Head injury
  7. Huntington's disease
  8. Lyme disease
  9. Multiple sclerosis
  10. Muscular dystrophy
  11. Myasthenia gravis
  12. Parkinson's disease
  13. Stroke
  14. Wilson's disease

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


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.