Читать книгу Neurology - Charles H. Clarke - Страница 147

When a muscle is denervated, spontaneous contraction of individual fibres begins to occur after 7–14 days. These contractions produce tiny fibrillation potentials of amplitude <10–200 μV. Fibrillation in a limb is invisible, but visible in the tongue, typically in MND. Positive sharp waves are bi‐phasic potentials with a longer duration (<10 ms) than fibrillations and usually with amplitudes of 10–200 μV, also seen in denervation.

Fasciculation describes the visible twitching of a muscle seen in various situations. In normal people, benign fasciculation is common in calf and other muscles. In denervated muscle, fasciculation potentials are produced by spontaneous discharges of motor units, and visible – often widespread in MND.