Vibrotactile threshold measurement for detecting peripheral neuropathy: defining variability and a normal range for clinical and research use.

AIMS/HYPOTHESIS: We aimed to define normal ranges for vibration sense as measured by vibratory perception thresholds (VPTs) using biothesiometry.

METHODS

We performed biothesiometry in a community-dwelling sample of 901 people aged 55 to 85 years who did not have diabetes. We quantitated the variation between repeat measures using analysis of variance and Bland-Altman plots. We also plotted the age- and sex-specific reference ranges.

RESULTS

We found small but statistically significant differences between repeat measures using the ascending and descending method of limits. Statistically higher vibration thresholds were noted on the right arm and leg compared with the left. Significantly higher vibration thresholds were also seen in men vs women for both lower limbs. We also defined sex-specific reference intervals (normal ranges) for biothesiometry for older persons and quantitated the increase in vibration threshold with increasing age.

CONCLUSIONS/INTERPRETATION: For reliability, it may be sufficient to obtain the average of two ascending measures separated by at least 1 min in just the right hand or right foot, since this is usually the one with the higher threshold. Although identical reference ranges can be used for men and women for the upper limb, there are significant differences in the lower limbs. The major determinant of VPT is age: we have established age-specific norms for VPT testing for adults between 55 and 85 years of age.