Altered supernormality in multiple sclerosis peripheral nerve.
Supernormality is a regular part of the recovery cycle of nerve. Supernormality was expressed in terms of amplitude, and in 20 control subjects the mean (S2 conditioned/S2 unconditioned) ratio of the median sensory nerve action potential amplitude recorded at the elbow measured 285 +/- 174 (range 119 to 783). A supramaximal conditioning shock was delivered 6 msec in advance of the test pulse. Seventeen (42.5%) of 40 patients with multiple sclerosis (MS) failed to demonstrate supernormality, the (S2 conditioned/S2 unconditioned) ratio being less than 100. This abnormality probably reflects a delay in recovery cycle and is additional evidence implicating peripheral nervous system involvement in multiple sclerosis.
D000328:Adult; D000368:Aged; D004558:Electric Stimulation; D005071:Evoked Potentials; D005260:Female; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000503:physiopathology*; D008875:Middle Aged; D009103:Multiple Sclerosis / Q000503:physiopathology*; D009431:Neural Conduction; D009435:Synaptic Transmission