Arm Length-Does It Influence Late Response in a Nerve Conduction Study?

Introduction  F wave response, a late response obtained from a motor nerve, can be influenced by various external factors like gender, temperature, height, weight, and limb length, and hence it causes variation in the measured parameters. Since very few studies have studied the impact of arm length on the F wave, this study was conducted to analyze the relation between the arm length on various parameters of F wave and hence to consider the importance of it during conduct of a nerve conduction study. Methods  The study was conducted among 40 healthy individuals and 40 diabetics with neuropathy. The arm length was measured in the upper limbs in both the groups and F wave was recorded following a conventional procedure using a standardized instrument. Results  This study showed that in the upper limbs of both the groups, there existed a positive correlation for certain parameters like minimum, maximum and mean latencies, persistence, FM latency and M latency, and a negative correlation for chronodispersion. Conclusion  F wave parameters should be adjusted for arm length to improve the sensitivity and diagnostic ability of neurological testing.