myokymia
Pronunciation: my-oh-KY-mee-ah
Continuous involuntary muscle contractions producing a rippling or undulating appearance of the muscle surface.
Full Definition
Myokymia is characterized by continuous, involuntary muscle contractions that create a rippling or undulating movement visible beneath the skin surface. On electromyography, myokymia appears as grouped motor unit discharges firing at regular intervals, creating a characteristic waxing and waning pattern. This phenomenon can occur in various conditions including peripheral nerve hyperexcitability syndromes, radiation-induced nerve injury, or as a benign finding in facial muscles. Myokymia differs from fasciculations by its continuous nature and distinctive EMG pattern.
Usage
Usage note: From Greek meaning 'muscle wave'; distinguish from myoclonus which is sudden, brief jerks.
In Context
- "Facial myokymia was observed as a late complication of radiation therapy to the brainstem." — Neurological examination
- "The EMG revealed characteristic myokymic discharges in the affected muscle groups." — Electrodiagnostic study