fasciculation
Pronunciation: fas-ik-yuh-LAY-shun
Involuntary muscle twitching visible under the skin, often indicating lower motor neuron disease.
Full Definition
Fasciculations are spontaneous, involuntary contractions of muscle fibers that are visible as brief twitches under the skin. They result from abnormal electrical discharges in motor neurons and are a key clinical sign in the diagnosis of motor neuron diseases such as amyotrophic lateral sclerosis (ALS). Fasciculations can occur in healthy individuals, particularly after exercise or caffeine consumption, but persistent, widespread fasciculations combined with muscle weakness and atrophy suggest pathological conditions. In clinical documentation, the location, frequency, and association with weakness are important diagnostic features to record accurately.
Usage
Usage note: Distinguish from fibrillation (not visible) and myoclonus (larger, jerky movements).
In Context
- "Widespread fasciculations were observed in the patient's arms and legs, concerning for motor neuron disease." — ALS evaluation
- "Benign fasciculations in the calf muscles resolved after discontinuing excessive caffeine intake." — follow-up note