SENSORY NERVE FINDINGS BY TACTILE STIMULATION OF MEDIAN AND ULNAR NERVES IN HEALTHY-SUBJECTS OF DIFFERENT AGES

We studied orthodromic sensory conduction velocity along the distal an d proximal segments of the median and ulnar nerves by tactile stimulat ion of the distal phalanx of the 3rd and 5th digits in 44 healthy subj ects divided into 2 age groups: from 16 to 35 years and from 63 to 81 years. In the same nerves, we used selective electrical stimulation of the corresponding digital nerves to obtain sensory potentials. In bot h groups, responses to tactile stimuli had a longer latency and smalle r amplitude than those to electrical stimulation, and they were distri buted in a series of 6-7 main deflections, apparently regardless of wh ether the recording site was distal or proximal. Moreover, irrespectiv e of the nerve and of subject age, conduction velocity along both the digit-wrist and the wrist-elbow nerve segments was significantly slowe r with tactile stimuli than with electrical stimuli. However, independ ently of the stimulus used, conduction velocity along the proximal ner ve segment was significantly faster than that measured along the digit -wrist nerve segment. In both the median and ulnar nerves, maximum pot ential amplitude, cumulative area and conduction velocity were signifi cantly reduced in the older age group. This finding could reflect the smaller number of Meissner's corpuscles in older subjects, and the los s of large nerve fibres in individuals over 60.