Vestibular perception and the vestibulo-ocular reflex in young and older adults

OBJECTIVES:: Quantification of the perceptual thresholds to vestibular stimuli may offer valuable complementary information to that provided by measures of the vestibulo-ocular reflex (VOR). Perceptual thresholds could be particularly important in evaluating some subjects, such as the elderly, who might have a greater potential of central as well as peripheral vestibular dysfunction. The authors hypothesized that perceptual detection and discrimination thresholds would worsen with aging, and that there would be a poor relation between thresholds and traditional measures of the angular VOR represented by gain and phase on rotational chair testing. DESIGN:: The authors compared the detection and discrimination thresholds of 19 younger and 16 older adults in response to earth-vertical, 0.5 Hz rotations. Perceptual results of the older subjects were then compared with the gain and phase of their VOR in response to earth-vertical rotations over the frequency range from 0.025 to 0.5 Hz. RESULTS:: Detection thresholds were found to be 0.69 ± 0.29 degree/sec (mean ± standard deviation) for the younger participants and 0.81 ± 0.42 degree/sec for older participants. Discrimination thresholds in younger and older adults were 4.83 ± 1.80 degree/sec and 4.33 ± 1.57 degree/sec, respectively. There was no difference in either measure between age groups. Perceptual thresholds were independent of the gain and phase of the VOR. CONCLUSIONS:: These results indicate that there is no inevitable loss of vestibular perception with aging. Elevated thresholds among the elderly are therefore suggestive of pathology rather than normal consequences of aging. Furthermore, perceptual thresholds offer additional insight, beyond that supplied by the VOR alone, into vestibular function.