Abstract

INTRODUCTION
Although length-dependent axonal excitability changes have been reported in the median nerve, the mechanisms underlying these changes remain to be further clarified.
METHODS
Axonal excitability studies were performed on median nerve at the palm and wrist in 20 healthy controls, with responses recorded over the abductor pollicis brevis.
RESULTS
The strength-duration time constant was significantly shorter (palm: 0.35 ± 0.01 ms; wrist: 0.48 ± 0.03 ms; P < 0.001), whereas rheobase was significantly increased (palm: 2.90 ± 1.12 mA; wrist: 2.09 ± 1.11 mA; P < 0.05) at the palm. In addition, there was a significant increase in depolarizing threshold electrotonus at 90-100 ms (P < 0.001) and a reduction in S2 accommodation (P < 0.001) and late subexcitability (P < 0.001) at the palm. The changes in excitability were independent of factors influencing median nerve cross-sectional area.
CONCLUSIONS
The present study reveals significant length dependent changes in median nerve excitability which may reflect differences in intrinsic membrane properties.

Links

Publisher Full Text

Authors

Moore D, Menon P, Vucic S

Institution

Sydney Medical School Westmead, University of Sydney, Sydney, New South Wales, Australia.

Source

Muscle & nerve 45:4 2012 Apr pg 492-9

MeSH

Action Potentials
Adult
Aged
Anatomy, Cross-Sectional
Axons
Electric Stimulation
Electromyography
Female
Hand
Humans
Male
Median Nerve
Middle Aged
Muscle Contraction
Muscle Strength
Muscle, Skeletal
Neural Conduction
Potassium Channels
Wrist
Young Adult

Pub Type(s)

Journal Article

Language

eng

PubMed ID

22431081