The impairment of peripheral vibratory perception with advancing age is well known. This was originally assessed with a tuning fork (1, 2); latterly more quantitative techniques have been employed using electrical vibrometers (3)(4)(5)(6)(7)(8). When studying the effect of age on vibratory perception, it is necessary to exclude all other known factors which may affect this measurement. Although reports in the literature have stated that the subjects tested were free of such factors, insufficient emphasis has been placed on the selection of subjects with completely normal extremities. The present study, therefore, was undertaken to measure peripheral vibratory perception in such a group of aging persons.An electrical vibrometer was designed which had a frequency of 125 cycles per second. The amplitude of vibration was varied by altering the voltage applied to the vibrator, which consisted of an electromagnetic recording head carrying a blunt needle 1 inch long. The vibratory perception threshold was read in arbitrary "vibration units", 100 units being the maximum obtainable from the machine. (See Appendix for technical description and diagram of the vibrometer).
SUBJECTSOne hundred normal men were studied, ranging in age from 22 to 85 years. These were selected on the basis of history, physical examination, oscillometry and neurologic examination, and were considered to have completely normal extremities. Blood sugar determinations were performed on all of the older men, both fasting and after a meal. Results of serologic tests for syphilis were negative in all cases. None of the subjects had anemia. Particular care was taken to rule out the following: pernicious anemia, diabetes mellitus, peripheral neuritis, peripheral nerve injuries, other neurologic and psychiatric disorders, syphilis, vitamin deficiencies, and peripheral occlusive vascular disease of all types.
METHODSVibratory perception thresholds were measured in the hands and feet. For measurement in the hand, the subject was seated comfortably at a table with the hand resting on a slotted board through which the vibrator protruded. The index and fifth fingers were measured, the mid-point of the palmar aspect of the distal phalanx being applied to the vibrator. For measurement in the lower extremity, the foot was rested on a chair, and the vibrator was applied to the mid-point of the plantar surface of the distal phalanx of the big toe. In all cases, the purpose