Monograph: Single fiber electromyography and measuring jitter with concentric needle electrodes-Article

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Single fiber electromyography (SFEMG) and measuring jitter with concentric needle electrodes (CNEs) are techniques used to assess neuromuscular transmission (NMT) in various neuromuscular disorders. SFEMG involves recording action potentials from single muscle fibers, allowing for the measurement of fiber density (FD), a measure of reinnervation, and jitter, a measure of abnormal NMT. Jitter is the variation in the time it takes for endplate potentials to reach the action potential threshold, and increased jitter indicates impaired NMT. CNE recordings produce spikes that can be used to measure jitter, but the larger recording electrodes make it difficult to determine if the spikes come from single muscle fibers or multiple fibers. SFEMG and CNE recordings have similar sensitivity in detecting increased jitter in disorders such as myasthenia gravis, Lambert-Eaton myasthenic syndrome, and congenital myasthenic syndrome. However, jitter can also be seen in ongoing reinnervation and some myopathic conditions. SFEMG is more sensitive in detecting increased FD, and conventional electromyography should be used to assess neurogenic or myogenic abnormalities. Jitter measurements can help differentiate between different neuromuscular disorders, monitor disease progression, and assess the effectiveness of treatments. SFEMG and CNE recordings can also be used in other applications, such as latency measurements and assessing conduction velocity. Overall, SFEMG and jitter measurements are important tools in the evaluation and management of neuromuscular disorders.

Keywords

SFEMG

jitter measurement

neuromuscular transmission

CNE electrodes

fiber density

abnormal NMT

myasthenia gravis

congenital myasthenic syndrome

myopathic conditions

disease progression