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Volume 42 Number 6, November/December 2005
Pages 821 — 828

Abstract - Nerve conduction topography in geriatric hand assessment

Mohammed Ferdjallah, PhD;1 Jacqueline J. Wertsch, MD;2* Mohammad A. Ahad, MS;1 Gulapar
Phongsamart, MD;2 Kevin C. McGill, PhD3

1Department of Electrical and Computer Engineering, University of Tennessee, Knoxville, TN; 2Department of Physical Medicine and Rehabilitation, Zablocki Department of Veterans Affairs (VA) Medical Center, Medical College of Wisconsin, Milwaukee, WI; 3Rehabilitation Research and Development Center, VA Palo Alto Health Care System, Palo Alto, CA
Abstract — Motor nerve conduction is a noninvasive clinical test used to diagnose nerve problems such as carpal tunnel syndrome or peripheral neuropathy. Current techniques use a single-site recording over a superficial muscle. This traditional approach does not account for the electrical contributions from the other muscles innervated by the nerve being stimulated, which need to be considered with thumb carpometacarpal (CMC) degenerative joint disease (DJD) because these electrical contributions may change the anatomic relationship of the thenar muscles. This study recorded from 15 sites over the thenar eminence during motor nerve conduction studies of the median nerve of 12 young subjects with normal thenar anatomy and 25 elderly subjects with thumb CMC DJD. The maximum compound muscle action potential (CMAP) values did not occur in the same electrode position for the two groups, and traditional single-site recording would have resulted in smaller amplitudes and longer latencies for the elderly than the values noted with the multiple-site recordings. This pilot study of nerve conduction topography mapping with multiple-site recording illustrates that single-site studies may be misleading and supports further exploration of multichannel grid electrodes for topographic display and analysis of the CMAP.
Key words: CMAP amplitude, CMAP duration, CMAP latency, degenerative joint disease, hand with CMC DJD, median curve, nerve conduction, single-site recording, thenar muscle, topographic mapping.

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