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Updated: Aug 13, 2026

In Vivo Electrophysiological Measurement of the Rat Ulnar Nerve with Axonal Excitability Testing
Published on: February 6, 2018
Electrophysiologic correlates of weakness in L5/S1 radiculopathy
S N Scelsa1, A R Berger, S Herskovitz
1Department of Neurology, Albert Einstein College of Medicine, Bronx, New York, Beth Israel Medical Center. SScelsa@BethIsraelNY.org
Introduction:
Management of patients with radiculopathy involves estimating the degree of physiologic and anatomic injury, and weighing that to predict the likely clinical course.
Objective:
To determine whether low distal peroneal and tibial CMAP amplitudes correlate with weakness and fibrillations of functionally relevant muscles in L5/S1 radiculopathy (LSR).
Methods:
We reviewed clinical and electrophysiologic data in 66 consecutive patients with LSR.
Results:
A significantly greater number of patients with low peroneal CMAP amplitudes had weakness of L5 (p = 0.025) and S1 innervated leg muscles (p < 0.001). Low tibial CMAP amplitudes were also associated with weakness of S1 innervated muscles (p < 0.038). The association of low peroneal CMAP amplitudes with weakness persisted when weakness of at least 3 muscles was considered in the analysis for L5 (p < 0.0001) and S1 (p = 0.014) innervated muscles.
Conclusions:
Low peroneal and tibial CMAP amplitudes may serve as surrogate measures for segmental weakness of functionally relevant muscles in LSR.
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