Quantitative measurement of vibratory perception threshold using a new vibrometer TM-31A.

The need for standardization and validation of quantitative tests for vibratory sensitivity has been increasingly recognized. Conventional vibrometers have been of limited use for the assessment of vibratory perception threshold (VPT) due to wide intraindividual variations. This study describes the determination of VPT for the medial malleolus (MM), the styloid process of the radius (SPR), and the pulp of the index finger (PIF) in normal subjects, using a new vibrometer, the TM-31A. This apparatus expresses results in terms of actual vibration amplitude and has a feedback mechanism that avoids damping of the stimulator in tissue. Repeated VPT measurements revealed good reproducibility of the test. The intraday and day-to-day variations of VPT were fairly small. VPT was found to differ significantly among sites (MM > SPR > PIF). The distribution in MM was substantially log-normal, whereas the SPR and PIF were normal. VPT values on each site correlated with advancing age, especially on the MM. It is concluded that TM-31A provides a reliable and valid assessment of VPT and contributes to the standardization of VPT testing.