Does cortical motor neuron excitability change in peripheral nerve injury?
OBJECTIVE
To investigate changes in cortical motor neuron excitability after peripheral nerve injury, evoked spinal cord potentials (ESCPs) following hemispheric transcranial magnetic stimulation (TMS) were recorded in awake patients with unilateral brachial plexus injury.


METHODS
ESCPs following hemispheric TMS were recorded in 6 patients with unilateral complete type brachial plexus injury. Studies were performed within 6 months from the time of injury. ESCPs were recorded from posterior epidural space using catheter electrodes. Hemispheric TMS was applied on the motor cortex using a figure-of-8 coil. The threshold of ESCPs following hemispheric TMS was measured. The number, latency, and amplitude of ESCPs following high stimulus hemispheric TMS were measured and compared.


RESULTS
No significant change was observed in the threshold of ESCPs following TMS contra-lateral to the injured upper limb compared to that following TMS contra-lateral to the intact upper limb. Several ESCP components were recorded following high stimulus hemispheric TMS. No significant changes were observed in comparison with number, latency and amplitude of ESCPs following high stimulus TMS contra-lateral to the injured upper limb and those following TMS contra-lateral to the intact upper limb.


CONCLUSIONS
From a study of ESCPs following single TMS, no evidence was obtained that cortical motor neuron excitability changes in patients with traumatic unilateral brachial plexus injury at relatively early stages. We investigated the changes of cortical motor neuron excitability in patients with brachial plexus injury from the ESCPs following TMS. In single TMS, our data gave no evidence for cortical excitability changes at relatively early stages.
Kaneko
Kazuo
K
Department of Orthopaedic Surgery, Yamaguchi University School of Medicine, 1-1-1, Minami-Kogushi, 755-8505, Ube, Yamaguchi, Japan.
Taguchi
Toshihiko
T
Yonemura
Hiroshi
H
Ueno
Hiroyasu
H
Li
Zhenglin
Z
Kawai
Shinya
S
D000293:Adolescent; D000328:Adult; D001917:Brachial Plexus / Q000293:injuries* / Q000503:physiopathology; D020516:Brachial Plexus Neuropathies / Q000503:physiopathology*; D004558:Electric Stimulation; D019054:Evoked Potentials, Motor; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D006801:Humans; D008280:Magnetics; D008297:Male; D009044:Motor Cortex / Q000166:cytology / Q000502:physiology*; D009046:Motor Neurons / Q000502:physiology*