Development of a mobile-enabled vibration perception threshold device to screen for peripheral neuropathy

Abstract

A common complication of diabetes is distal symmetric polyneuropathy (DSPN), which is nerve damage that typically leads to a loss of tactile sensation in the feet and is a major cause of foot ulcers and leg amputations. A key limitation to current screening and ulcer prevention in India is the impracticality of current diagnostic equipment, which is expensive, bulky, and requires trained operators. Consequently, the majority of the Indian diabetic population in low-resource settings is currently not being tested for neuropathy. The Mobile-Enabled Diabetic Foot Analyzer (mDFA) is a portable neuropathy screening device that provides quantitative information about a diabetic patient's touch sensation in the foot. It connects wirelessly to a mobile phone or tablet, which can record sensation levels and track changes over time. The mDFA evaluates a person's nerve function by determining their vibration perception threshold (VPT) at a given skin location. VPT is defined as the lowest intensity of vibration that a person is able to feel at the application location. A probe, which vibrates at a fixed frequency of 100 or 120 Hz, is applied to the skin in a controlled manner. The vibration amplitude slowly increases until the person feels the vibration. The amplitude, recorded in microns, at that point is the VPT at that location. Higher than normal VPT is an indication of neuropathy. This thesis discusses the need for a neuropathy screening device that is appropriate for low-resource settings throughout the world, surveys current DSPN diagnostic techniques and devices, and describes the mDFA design as well as preliminary results from tests conducted on both normal and diabetic subjects.