Fasciculation and fibrillation are features of dysarthria a speech disorder involving respiration and muscle control of the throat. Dysarthria is characterized by slurred or slow speech that can be difficult to understand. Common causes of dysarthria is a neurological disorder such as stroke, brain injury, brain tumors, and conditions that cause facial paralysis or tongue or throat muscle weakness.
Fasciculation is visible spontaneous contractions of the throat. Fibrillations are invisible but are also muscle twitches. They may precede fasciculation. Both may occur in motor neurone disease.