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Threshold tracking techniques in the study of human peripheral nerve
Author(s) -
Bostock Hugh,
Cikurel Katia,
Burke David
Publication year - 1998
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/(sici)1097-4598(199802)21:2<137::aid-mus1>3.0.co;2-c
Subject(s) - refractory period , electrophysiology , nerve conduction velocity , neuroscience , membrane potential , myelin , rheobase , ion channel , medicine , chemistry , biology , anesthesia , central nervous system , receptor
Conventional electrophysiological tests of nerve function focus on the number of conducting fibers and their conduction velocity. These tests are sensitive to the integrity of the myelin sheath, but provide little information about the axonal membrane. Threshold tracking techniques, in contrast, test nerve excitability, which depends on the membrane properties of the axons at the site of stimulation. These methods are sensitive to membrane potential, and to changes in membrane potential caused by activation of ion channels and electrogenic ion pumps, including those under the myelin sheath. This review describes the range of threshold tracking techniques that have been developed for the study of human nerves in vivo: resting threshold is compared with the threshold altered by a change in environment (e.g., ischemia), by a preceding single impulse (e.g., refractoriness, superexcitability) or impulse train, or by a subthreshold current (e.g., threshold electrotonus). Few clinical studies have been reported so far, mainly in diabetic neuropathy and motor neuron disease. Threshold measurements seem well suited for studies of metabolic and toxic neuropathies but insensitive to demyelination. Until suitable equipment becomes more widely available, their full potential is unlikely to be realized. © 1998 John Wiley & Sons, Inc. Muscle Nerve 21: 137–158, 1998