Effect of arm length and body mass index on abductor pollicis brevis long latency reflex

Abstract

Background: Long-latency reflex (LLR) is one of the late responses that occur after H-reflex on submaximal stimulation of the mixed nerve. Studies have been done to known the influence of height, arm length, and body mass index (BMI) on nerve conduction study. However, there are hardly studies done to know the effect of arm length and BMI on latency and amplitude of abductor pollicis brevis (APB) LLR among females. Aims and Objective: The objective of the study was to know the effect of arm length and BMI on APB LLR. Materials and Methods: The present cross-sectional study was conducted among 30 healthy adult female volunteers between the age group of 20 and 30 years. LLR recording was done during early follicular phase of the participants using EP/digital nerve conduction/EMG/machine (Recorders and Medicare System, India). LLR was obtained during stimulation of median nerve while abducting the thumb of the dominant hand of the participants. The tabulated data were analyzed using Karl Pearson’s correlation coefficient. Results: Arm length was found to be positively correlated with APB LLR latency and negatively correlated with APB LLR amplitude with r = 0.280 and −0.110, respectively. BMI was found to be negatively correlated with both APB LLR latency and amplitude with r = −0.139 and −0.206, respectively. Conclusion: With increasing arm length, APB H-reflex latency increases, and amplitude decreases. With the increase in BMI, both APB H-reflex latency and amplitude decrease. Hence, arm length and BMI must be taken into consideration while interpreting APB H-reflex among females.