To Assess the Nerve Conduction Velocity Declination Rate According to Age in Median Nerve of Normal Healthy Subjects

Background Aging is a process that is often accompanied by physiological changes. These physiological changes include slowing in muscle contractility, alteration in muscles metabolism and neuromuscular junction and reduction in nerve conduction velocity. Age has been widely accepted to have an influence on nerve velocity. There is loss of both myelinated and unmyelinated nerve fibers. Potentially well documented effect on the function and electrophysiological properties of peripheral nerves. The most common age-related degenerative alteration is an accumulation of dark cytoplasm in pocket that is produced by splitting of the major dense line. Another but less common myelin alteration associated with aging is the formation of myelin balloons. The conduction velocities begin to decline after 30-40 years of age but the values normally change by less than 10m/s at 6th or even in 8th decade Materials and Methods Total 80 healthy subjects between age of 30-79 years were included in the study. They were divided into five different age groups. Subjects were excluded if they suffered from diabetes mellitus or any neurological disorders that affect nerve. The nerves tested were the median, ulnar, and sural nerves. The sites of stimulation for the median motor and ulnar motor were the wrist and elbow. The recording site for the median motor was at the abductor pollicisbrevis muscle and for the ulnar motor at the abductor digitiminimi muscle. For the sensory conduction test of median and ulnar nerves the site of stimulation was at the wrist. The recording was done at the index finger and at the little finger respectively. The site of stimulation for the sural nerve was at the calf and the recording was made at the lateral malleolus. A ground electrode was placed in between the stimulating and recording electrodes. The conduction distance was estimated with a flexible measuring tape. Results The result shows statistically significant decrease in nerve conduction velocities of median, ulnar and sural nerve with increasing age, after analyzing the data by SPSS version 20. The study shows decline in sensory nerve conduction velocity of median SNC (0.22m/s/year), ulnar SNC (0.28m/s/year) and sural nerves (0.17m/s/year), were more than motor nerve conduction velocity of median (0.19m/s/year) and ulnar (0.22m/s/year) nerves. Conclusion There appears to be a significant decline in the motor and sensory conduction velocity of median, ulnar and sensory conduction velocity of sural nerves with increasing age in the adult. This finding could be utilized in confirming the diagnosis of peripheral nerve diseases with clinical correlation.