Comparison of five methods for measurement of vibratory perception

Five methods for the measurement of vibratory perception (using three different vibrameters ) have been compared by determining the vibratory perception threshold in 12 subjects on two days (with a 3-d interval). One device with a vibrating rod (manufactured by MUAB ) was used, the rod being applied either to the finger-tip (rod-tip) and on the proximal phalanx (rod-phalanx). The other devices were fitted with vibrating pins. In one apparatus all pins vibrated in phase (pin-phase), in the other ( Optacon ) the pins in adjacent rows vibrated in opposite phase. The latter one was used with a continuous (pin-cont) and with a "yes-no" procedure (pin-y/n). Mean vibratory perception threshold differed considerably: from 0.09 micron (pin-y/n) to 0.61 micron (pin-phase). No learning effect was found between the two days of measurement. The correlation between the measurements on both days (a measure for the reproducibility) was about the same for all methods (from 0.71 to 0.86). Intra-individual variation amounted to 30 to 50%. The low correlation of pin-cont and pin-y/n with the other methods (0.06 to 0.44), if compared with the correlations among the remaining methods (0.53 up to 0.83), suggests that with the Optacon different sensory properties are measured. Apart from the unclear relevance of the measurement of vibratory perception for early diagnosis of neurologic diseases, these results indicate that further investigation and standardization of methods is necessary before they can be used in practice as a screening-method.