Electrophysiologic analysis of the motor system after stroke: the flexor reflex
Fisher, M.A.; Shahani, B.T.; Young, R.R.
Archives of Physical Medicine and Rehabilitation 60(1): 7-11
1979
ISSN/ISBN: 0003-9993 PMID: 311188 Document Number: 148193
Flexor reflexes, evoked by electrical stimulation of the tibial nerve, were recorded electromyographically from the tibials anterior muscle in a clinically involved lower limb 37 times in 30 patients with cerebrovascular lesions. Of these studies 32 were performed within 4 wk of the ictus, while in 5 the lesions were of longer duration. Compared with studies on the uninvolved limbs, there was a significant delay in latency (defined as > 90 ms) and prolongation of the duration (defined as > 150 ms) of the minimal-latency flexor reflexes. These changes were associated with the absence of a 2-component flexor reflex response seen in normal subjects. Abnormalities of the electrically elicited flexor reflex did not correlate with the presence or absence of abnormal plantar reflex (Babinski response), changes in deep tendon reflexes, or degree of weakness. Increase in tone was present in 7/20 studies in patients with significant abnormalities in contrast to only 1/18 without. Thus changes in the flexor reflex (along with other physiologic parameters) provide a method for defining alteration in the motor system based on reproducible electrophysiologic criteria. In addition to documenting reflex changes from the acute to the chronic phase after stroke, this physiologic approach will lead to development of specific forms of therapy based on recognition of specific forms of therapy based on recognition of specific pathophysiology produced by discrete CNS lesions.