Neurológia pre prax 2/2010

Neurophysiology and electrodiagnosis of neuromuscular transmission

This review summarizes the principles of normal neuromuscular transmission. Depolarization of the nerve terminal produces an influx of calcium through voltage-gated calcium channels and acetylcholine vesicles then fuse with the presynaptic membrane. After release, acetylcholine (ACh) interacts with the acetylcholine receptor (AChR); this opens the AChR channel, resulting in an influx of sodium. When a sufficient quantity of ACh binds to the receptors, sodium channels in muscle membrane open, leading to depolarization of the muscle and contraction. Electrodiagnostic studies can demonstrate a defect of neuromuscular transmission in two ways. The first is by repetitive nerve stimulation at slow rates 2–3 Hz and detection of decrement. The second is by performing single fiber electromyography and evaluating jitter or neuromuscular block.

Keywords: neuromuscular junction, neuromuscular transmission, repetitive nerve stimulation, single fiber electromyography.