Standard nerve-conduction studies can lead to unnecessary surgery

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Standard nerve-conduction studies can lead to unnecessary surgery



May 11, 2006



Gandey

Knoxville, TN - Researchers say that standard nerve-conduction

studies do not take into account the electrical contributions of

other muscles affected by the stimulated nerve and can lead to

unneeded procedures. Reporting in the Journal of Rehabilitation

Research and Development, the group recommends multisite recordings

instead [1]. " Avoiding false-positive studies and unnecessary surgery

for carpal-tunnel syndrome in elderly individuals was the driving

force behind this study, " say the researchers, led by Dr Mohammed

Ferdjallah (University of Tennessee, Knoxville).

Motor nerve conduction is a noninvasive clinical test used to

diagnose nerve problems. Current techniques use a single-site

recording over a superficial muscle. But the investigators note that

the electrical contributions of other nerves need to be considered

with thumb carpometacarpal degenerative joint disease, because these

electrical contributions may change the anatomic relationship of the

thenar muscles.

This pilot study explored nerve-conduction topography by recording

from multiple sites. The researchers used 15 electrode sites to map

the compound muscle action potential distribution on the thenar

muscle for both young healthy individuals and elderly individuals

with thumb carpometacarpal degenerative joint disease. They looked at

a total of 12 young subjects with normal thenar anatomy and 25

elderly subjects with thumb joint disease.

The investigators found that the maximum compound muscle action

potential 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.

" We found it very interesting that the recording electrode site

giving the largest amplitude was different for the elderly with

carpometacarpal degenerative joint disease compared with the young

normal hands, " comment the researchers. " As would be expected, for

most of the young normal hands, one particular site—site 7—showed

the maximum number of highest compound muscle action potential

amplitude. In the case of degenerative-joint-disease elderly hands,

however, different electrode locations registered highest amplitude. "

Ferdjallah and his team conclude that the tradition of using a single

electrode in a standardized location might not be adequate. This

study illustrates the value of topographic thenar mapping with

multiple-site recordings and lays the foundation for the development

of multichannel topographic nerve-conduction studies.

The researchers add that this aim is realistic with current

technology and " would offer a significant technical advancement

compared with the current single-site recording nerve-conduction

studies. "

http://www.jointandbone.org/viewArticle.do?primaryKey=697767