Premium
Nerve excitability properties in lower‐limb motor axons: Evidence for a length‐dependent gradient
Author(s) -
Krishnan Arun V.,
Lin Cindy S.Y.,
Kiernan Matthew C.
Publication year - 2004
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.20013
Subject(s) - rheobase , refractory period , electrophysiology , anatomy , stimulus (psychology) , neuroscience , medicine , tibialis anterior muscle , motor nerve , biology , anesthesia , psychology , skeletal muscle , psychotherapist
In this study, nerve excitability protocols were adapted for lower‐limb recordings in 25 healthy subjects to enable comparison of excitability parameters between proximal and distal recording sites of the same nerve and between different nerves. Excitability parameters (stimulus–response curves, strength–duration properties, threshold electrotonus, a current–threshold relationship, and the recovery cycle) were recorded from tibialis anterior, extensor digitorum brevis, and abductor hallucis. Excitability recordings were technically possible from each site, and normative values were established for lower‐limb nerves. In this process, inter‐ and intranerve differences in excitability properties were demonstrated: stimulus intensity and rheobase were reduced in recordings from proximal sites; the relative refractory period and late subexcitability were increased; superexcitability was reduced; and a relative “fanning‐in” occurred for threshold electrotonus curves recorded from proximal sites. Such a length‐dependent gradient in nerve excitability may underlie the greater tendency for ectopic activity to arise from the proximal segments of motor axons and may contribute to the length‐dependent involvement of motor axons in the development of peripheral neuropathy. Muscle Nerve 29: 645–655, 2004