The Journal of Bone and Joint Surgery, Vol 67, Issue 8 1219-1224, Copyright © 1985 by Journal of Bone and Joint Surgery, Inc
Lower-extremity sensibility testing in patients with herniated lumbar intervertebral discs
MD Weise, SR Garfin, RH Gelberman, MM Katz and RP Thorne
The significance of sensory changes determined by pinprick and light touch
in individuals with a herniated lumbar disc has been questioned.
Discrepancies may be related to the subjectiveness of the test, failure to
use dermatome-specific testing sites, overlap of areas that are innervated
by different nerve roots, anatomical variations, or lack of sensitivity of
the testing technique. For this study, we assessed the results of sensory
examinations of twenty-five patients with documented herniation of a lumbar
disc. The examinations were done using Semmes-Weinstein monofilaments,
vibrometry, pinprick, and light touch in the autonomous skin areas supplied
by the fourth and fifth lumbar and first sacral-nerve roots. Right-left
differences in Semmes-Weinstein pressure thresholds of more than fifteen
milligrams per square millimeter enabled us to localize disc lesions to a
specific root in 100 per cent of patients and differences in vibratory
thresholds of more than 3.5 micrometers, to localize the correct level in
88 per cent. Lesser differences in thresholds did not help to identify the
involved root. The mean sensory threshold on the side of the disc lesion
was found to be significantly greater than that on the opposite side by
both vibrometry and pressure aesthesiometry (p less than 0.005). These
findings were not duplicated using light touch or pinprick testing. Even
with the most sophisticated sensibility-testing techniques, correct
identification of the nerve root that was compressed by a herniated lumbar
disc was accurate in only 50 per cent of patients.
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