Examination of sensory nerve fibers by needle recording in the carpal tunnel syndrome; use of the orthodromic method with special attention to the paresthetic forms.

Abstract

The authors examined clinically, by EMG and by electrostimulation the motor and sensory fibers of the median nerve in 15 control hands (group A), 35 hands with the paresthetic form of CTS (group B), and 33 hands with CTS and pathologic DML (group C). The examination of the sensory fibers was performed on the first (thumb) to 4th digits separately by the orthodromic technique with monitoring the NAP by needle electrodes from the wrist. Two hundred fifty six responses were averaged out and always 4 stimulatory values were followed on the sensory fibers. The highest percentage of pathologic values by DSL in group B was on the first digit (thumb: 37%), in group C on the 3rd digit (93%). By DSCV the highest number of pathologic values in groups B and C was on the thumb (43 and 90 per cent respectively), for NAP duration in groups B and C on the third digit (26 and 60 per cent respectively). In the controls the mean amplitude of NAP fluctuated between 19-50 uV. The best parameters are considered: the DSL, DSCV, somewhat less the duration of NAP. In the paresthetic form of CTS pathologic values of sensory parameters fluctuated between 8.6-42.8 per cent, in the group with pathologic DML in the range of 24.2-93.3 per cent. If one considered pathologic an examination that had at least one pathologic sensory parameter at least on one digit, group B yielded 77 per cent, and group C 100 per cent of pathological results.(ABSTRACT TRUNCATED AT 250 WORDS)