Nerve conduction studies and vibration perception thresholds in diabetic and uremic neuropathy

Two parameters of nerve conduction studies (nerve conduction velocities and amplitudes of the evoked sensory and motor responses) were compared with quantitative vibration perception thresholds (VPT) in patients with peripheral neuropathy (diabetes mellitus and/or end-stage renal disease). VPT measurements were made using a "two-alternative, forced-choice" method in which the patient is required to identify which of the two rods is vibrating at progressively decreasing vibration intensities. VPTs correlated significantly with nerve conduction velocities in all upper and lower extremity sensory and motor nerves tested, and with the amplitudes of the evoked motor responses in three motor nerves: median and ulnar (motor components) and tibial. For the median and ulnar nerves (motor components) the amplitudes of the evoked motor responses were more sensitive than nerve conduction velocities in correlation with VPTs. Comparison of VPT values, based upon whether or not evoked sensory and motor responses were obtained, indicated that mean VPTs were consistently higher among subjects in whom these evoked responses were not elicited. VPT measurements is thus shown to be a valid and valuable method for evaluation of severity in peripheral neuropathy. It has the advantages of being simple, quick and painless. Patient cooperation and compliance with this form of testing are excellent.