myokymia
Pronunciation: my-oh-KY-mee-ah
Continuous muscle fiber activity producing undulating, rippling movements visible on the skin surface and characteristic EMG patterns.
Full Definition
Myokymia refers to spontaneous, continuous muscle fiber contractions that create a rippling or undulating appearance beneath the skin. On electromyography, it appears as groups of motor unit potentials firing in brief bursts with short intervals between bursts, creating a characteristic 'marching' pattern. Myokymia can be benign (such as eyelid twitching) or pathological, associated with conditions like multiple sclerosis, brainstem lesions, or radiation-induced nerve damage. The EMG pattern is distinct from fasciculations and helps differentiate various neuromuscular conditions.
Usage
Usage note: Distinguish from fasciculations which are irregular and less continuous.
In Context
- "EMG revealed myokymia in the orbicularis oculi muscle, explaining the patient's persistent eyelid twitching." — Electromyography report
- "Facial myokymia developed following brainstem radiation therapy for the patient's acoustic neuroma." — Post-treatment follow-up