A sensitive method for the detection and quantification of conduction deficits in nerve.
A method is described which characterises the conduction deficit of a nerve in terms of the distribution of the refractory periods of transmission (RPTs) of its constituent fibres. The RPT is a particularly sensitive index of conduction deficit and measures the ability of a nerve fibre to conduct pairs of closely spaced impulses. The distribution of RPT in the nerve is represented as a graph, the RPT spectrum. Although the RPT spectrum is derived from recordings of the monophasic compound action potential, it is independent of changes in the conduction velocity of the constituent nerve fibres. The method is a particular value in the investigation lf lesions which are short or in which only a small proportion of the fibres present are affected. An investigation is described which examines the similarity between the RPT spectrum, derived from recordings of the compound action potential, and the frequency distribution histogram of RPT derived from a study of individual fibres from the same nerve. A recent study (Smith and Hall 1980) has shown that when the conduction deficit resulting from a lesion is described in terms of the RPT spectrum, a close correlation can be drawn between the physiological properties of the nerve, its histological appearance at the lesion, and the severity of the resulting behavioural deficit.
D000200:Action Potentials; D000818:Animals; D002415:Cats; D004568:Electrodiagnosis / Q000379:methods; D006801:Humans; D009431:Neural Conduction; D010523:Peripheral Nervous System Diseases / Q000175:diagnosis*; D012032:Refractory Period, Electrophysiological