fibrillation potential
Spontaneous electrical activity from denervated muscle fibers, appearing as small diphasic potentials on EMG.
Full Definition
Fibrillation potentials are spontaneous action potentials arising from individual denervated muscle fibers, characterized by small amplitude (typically 20-200 microvolts), short duration diphasic or triphasic waveforms with initial positivity. These potentials indicate loss of nerve supply to muscle fibers and are pathognomonic of denervation when found in clinically weak muscles. Fibrillations typically appear 2-3 weeks after nerve injury and may persist for months to years depending on the degree of reinnervation.
Usage
Usage note: Distinguish from atrial fibrillation; in neuromuscular context, refers specifically to muscle fiber activity.
In Context
- "Abundant fibrillation potentials indicated acute denervation in the affected muscle groups." — EMG report
- "The presence of fibrillation potentials confirmed ongoing denervation despite clinical improvement." — Follow-up electrodiagnostic study