F-response multiplicity in lower motor neuron disorders.
Multiple F-response following a single supramaximal distal nerve stimulation was observed in about 4% of the patients suffering from disorders of lower motor neuron. The phenomenon was observed in old poliomyelitis, entrapment neuropathies, axonopathies and demyelinating neuropathies. Thirty healthy subjects and 30 patients of upper motor neuron disorder were also studied for this purpose but none showed F-multiplicity. On repeated stimulation at sufficient intervals, some or all the components of the multiple F-response could be reproduced individually or in different combinations with similar latency and morphology. These responses had all the characteristics of F-response and were distinguishable from H-reflex or axon reflex. Increase in the number and frequency of repeater F-response and markedly increased chronodispersion were also observed consistently in association with multiple F-responses. Multiplicity in the F-response is a hitherto unknown phenomenon of relatively rare occurrence, presence of which however, is always indicative of disease of the lower motor neuron. The possible mechanisms of its generation are discussed.
Pradhan
S
S
Department of Neurology, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow, India.
D000200:Action Potentials; D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D003711:Demyelinating Diseases / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016472:Motor Neuron Disease / Q000503:physiopathology*; D009046:Motor Neurons / Q000502:physiology