jitter
Variability in the time interval between two muscle fiber action potentials from the same motor unit, measured in single-fiber EMG.
Full Definition
Jitter represents the microsecond variability in the interpotential interval between two muscle fiber action potentials belonging to the same motor unit, as measured during single-fiber electromyography. Normal jitter reflects the physiological variation in neuromuscular transmission time, while increased jitter indicates impaired neuromuscular junction function. Jitter is quantified as the mean consecutive difference (MCD) of interpotential intervals, typically measured in microseconds. Elevated jitter values suggest neuromuscular junction disorders such as myasthenia gravis, Lambert-Eaton syndrome, or botulism. Jitter analysis is one of the most sensitive tests for detecting neuromuscular transmission abnormalities.
Usage
Usage note: Always specify the muscle tested and provide reference values when reporting jitter measurements.
In Context
- "Increased jitter values in the frontalis muscle supported the diagnosis of generalized myasthenia gravis." — Single-fiber EMG report
- "The patient's jitter measurements exceeded normal limits in 60% of recorded fiber pairs." — Neuromuscular junction study