Dysarthria: Speech that is characteristically slurred, slow, and difficult to understand. A person with dysarthria may also have problems controlling the pitch, loudness, rhythm, and voice qualities of his or her speech. Dysarthria is caused by paralysis, weakness, or inability to coordinate the muscles of the mouth. Dysarthria can occur as a developmental disability. It may be a sign of a neuromuscular disorder such as cerebral palsy or Parkinson's disease. It may also be caused by a stroke, brain injury, or brain tumor. Treatment of dysarthria includes intensive speech therapy with a focus on oral-motor skill development.