Vibration perception threshold and the law of mobility in diabetic mellitus patients

Abstract 

Background

Diabetic neuropathy is a family of nerve disorders with progressive loss of nerve function in 15% of diabetes mellitus (DM) subjects. Vibration Perception Threshold (VPT) is one of the modalities of testing loss of protective sensation. Law of mobility for VPT is well known for normal subjects, but not for diabetic subjects. This is a pilot study to evaluate and plot the law of mobility for VPT among DM subjects.

Methods

We used biothesiometer to find the VPT of several areas in upper and lower extremities for normal and diabetic subjects. VPT of normal and diabetic subjects for different foot areas from proximal to distal is evaluated for 30 subjects. All the subjects are screened for peripheral artery occlusive disease with ankle brachial pressure index (0.9 or above). VPT values of different areas are arranged in a proximal to distal order for the analysis.

Results

VPT values monotonically decrease from proximal to distal areas. Vierodt's law of mobility holds well for normal subjects in both feet areas. The law of mobility does not hold good for the DM subjects in one or both feet areas.

Conclusions

The VPT value of diabetic subjects reveals that the law of mobility do not holds good for diabetic subjects in foot areas. Though the number of subjects is small, all the subjects defied the law.

Keywords: Diabetic neuropathy, Mobility law, Verdotts's law, Two-point discrimination, Sensitivity test, Neuropathy test, Proximal to distal, Geometry law