Neurophysiological assessment of peripheral neuropathy through whole plantar nerve conduction in type 2 diabetes mellitus and healthy control subjects

Aim: To neurophysiologically characterize the innervation of the sole and assess the diagnostic efficacy of whole plantar nerve (WPN) conduction study in type 2 diabetes mellitus (T2DM) patients and healthy control subjects. Methods: This single-center prospective observational case-control study involved 51 individuals with T2DM and 34 healthy controls. All subjects underwent validated screening tests for peripheral neuropathy (PN), including proximal and distal sural nerve conduction study and WPN. Results: The median amplitude of the compound nerve action potentials (CNAPs) and the sensory conduction velocity (SCV) recorded by WPN conduction were significantly lower in patients with T2DM as compared to healthy controls. Sural nerve conduction revealed that both proximal and distal sensory nerve action potentials amplitude and SCV were significantly lower in subjects with diabetes, as compared to healthy controls. As compared with sural nerve conduction, WPN shows a Sensitivity of 77% and a negative predictive value (NPV) of 77%. Conclusions: WPN conduction study is helpful in characterizing the most distal nerve fibers in patients with T2DM and healthy controls. WPN may represent a useful tool in the diagnosis of length-dependent diabetic polyneuropathy.