jitter
Variability in neuromuscular transmission timing measured during single-fiber electromyography, reflecting neuromuscular junction function.
Full Definition
Jitter refers to the variability in the time interval between action potentials from two muscle fibers belonging to the same motor unit, measured during single-fiber electromyography (SFEMG). This parameter reflects the stability of neuromuscular transmission at the motor end-plate. Normal jitter values are typically less than 20-30 microseconds depending on the muscle tested and patient age. Increased jitter indicates impaired neuromuscular transmission and is seen in conditions affecting the neuromuscular junction such as myasthenia gravis, Lambert-Eaton syndrome, and botulism. Jitter measurement is considered the most sensitive electrophysiological test for detecting neuromuscular junction disorders.
Usage
Usage note: In neuromuscular contexts, always distinguish from general usage of 'jitter' meaning nervousness.
In Context
- "The patient showed markedly increased jitter values consistent with neuromuscular junction pathology." — SFEMG report
- "Normal jitter measurements effectively ruled out myasthenia gravis in this case." — Diagnostic assessment