fasciculation
Pronunciation: fas-ik-yuh-LAY-shun
Involuntary muscle twitching visible under the skin, often indicating nerve dysfunction.
Full Definition
Fasciculations are spontaneous, involuntary contractions of muscle fiber bundles (fascicles) that appear as brief, irregular twitches visible under the skin. These movements result from abnormal spontaneous firing of motor neurons and can indicate lower motor neuron disease, metabolic disturbances, or medication effects. While benign fasciculations are common and usually harmless, persistent widespread fasciculations may suggest serious conditions like amyotrophic lateral sclerosis (ALS). They differ from fibrillations, which are single muscle fiber contractions not visible to the naked eye and detectable only by electromyography.
Usage
Usage note: Distinguish from fibrillations (single fiber contractions) and myoclonus (sudden jerky movements).
In Context
- "Widespread fasciculations in the tongue and limbs raised concern for motor neuron disease." — neurological examination
- "Benign fasciculations resolved after discontinuing the offending medication." — follow-up visit