Vibration perception in normal man and medical patients.

Interest in sensitivity to vibration as an aid to neuro- logical diagnosis began in 1889 when Rumpf tested this function in a case of syringomyelia (Fox and Klemperer, 1942).Subsequent investigators found altered vibratory sensitivity in various disorders of the nervous system (e.g., Williamson, 1922).Reduced sensitivity, for example, has been reported in peri- pheral neuritis, diabetes mellitus, and pernicious anaemia (e.g., Cosh, 1953), while hypersensitivity has been seen in the Parkinsonian syndrome (Gordon, 1945).'Changes in vibratory sensitivity have been used as positive or negative diagnostic indicators (e.g., Canelas, 1958).Unfortunately, efforts to establish a simple, standard clinical routine for testing vibratory sensitivity have been plagued by a variety of prob- lems.The first one concerns age and sex differences.Although vibratory sensitivity diminishes with ageing (e.g., Newman and Corbin, 1936; Laidlaw and Hamilton, 1937), few clinical investigations have allowed for this effect.This is quite surprising when one considers the high mean age of patients display- ing certain clinical neurological symptoms.Possible sex differences also have been investigated (Mirsky, Futterman, and Broh-Kahn, 1953; Steiness, 1957; Detre, Feldman, Rosner, and Ferriter, 1962), but the results are inconclusive.Many approaches to clinical testing of vibration also have suffered procedural difficulties, such as inadequate control of the stimulus or of the routine (see discussion in Steiness, 1957).In earlier investiga- tions, furthermore, thresholds were measured at one.or, at most, a few frequencies.Since vibratory thresholds are a U-shaped function of frequency