Peroneal nerve motor conduction to the extensor digitorum brevis.

Abstract

Peroneal motor studies to the extensor digitorum brevis are commonly performed in electrodiagnosis. They have been investigated by many authors to derive the normal ranges for latency, amplitude, and nerve conduction velocity. Many of these studies, particularly the older ones, have methodological limitations, especially in light of modern technique and statistical applications. They often used small sample sizes. The objective of this study was to generate an expanded database of normative values for the peroneal nerve. In this study, 242 asymptomatic subjects without risk factors for neuropathy were tested, and their peroneal motor response was analyzed for latency, amplitude, area, duration, and nerve conduction velocity. Side-to-side and proximal-to-distal variation was recorded. Mean +/- 2 standard deviations (SD) and percentiles of normality are presented. Mean onset latency was 4.8 ms (SD, 0.8). Mean amplitude was 6.8 mV (SD, 2.5) and 5.1 mV (SD, 2.5) for the younger and older than 40-yr age groups, respectively. Mean nerve conduction velocity ranged from 44 to 49 m/s, depending on the demographic group (SD, 4-5). The upper limit of normal side-to-side latency variation was 1.4 ms (mean + 2 SD). The upper limit of normal drop in nerve conduction velocity from the low leg to the across knee segment was 10 m/s (mean - 2 SD) or 12% (97th percentile). The upper limit of normal amplitude difference from side to side was 61 % (at the 97th percentile), and the upper limit of normal drop in amplitude from below to above the fibular head stimulation was 25% (at the 97th percentile). The other measures are presented in the article.