Fixed distance based determination of normative range of median nerve electro-diagnostic parameters

Objectives Nerve conduction study is important diagnostic tool for exploring the median nerve neuropathy. This study aims to explore reference electrophysiological values for the median nerve in a sample of the East Indian population for normative data based on various anthropometric parameters and fixed distance recording among healthy adult subjects. Materials and Methods The study was cross-sectional at the All India Institute of Medical Sciences, Kalyani, West Bengal. After a thorough clinical evaluation, 128 hands of 64 healthy volunteers, aged between 18 and 60 years, were chosen for screening for systemic diseases or any major conditions affecting the nerves and muscles. The lengths of the arm, forearm, and wrist circumference were measured at specific reference distances. Nerve conduction studies (NCS) were carried out following standardized protocols. Motor nerve conduction data collection included median nerve distal latency, distal amplitude (DAmp), proximal latency, proximal amplitude, and conduction velocity (CV). Sensory nerve conduction data included onset latency, DAmp, and CV at 120 mm, 140 mm, and 160 mm distances from the site of stimulation. Data analysis was performed using the Statistical Package for the Social Sciences version 22. Results The mean and standard deviation of all parameters were calculated. NCS parameters were also determined at various percentiles. Linear regression models showed a negative link between sensory median nerve latency and increased distance from the point of stimulation. The models also provided coefficients indicating changes in NCS parameters for unit changes in body mass index (kg/m 2 ), arm length, forearm length, and wrist circumference, individually for males and females. Conclusion The study identified variations in median nerve electrophysiological values, with regression models demonstrating different associations with various parameters.