Impact of Arm Length and Body Mass Index on Abductor Pollicis Brevis (APB) H-Reflex among Females

Introduction: Hoffmann reflex (H-reflex) is an electrically induced reflex analogous to the mechanically induced spinal stretch reflex. H-reflex is useful clinically to diagnose nerve root lesions, particularly involving S1 radiculopathy and in proximal nerve lesions. H-reflex is affected by various physiological factors like age, height and gender. However, there are only few studies done to determine the effect of arm length and Body Mass Index (BMI) on latency and amplitude of Abductor Pollicis Brevis (APB) H-reflex among females. Aim: To determine the impact of arm length and BMI on APB H-reflex among females. Materials and Methods: The present cross-sectional study was done on 50 healthy adult female volunteers during early follicular phase between age group of 20-30 years. After measuring arm length and BMI, APB H-reflex was recorded by stimulation of median nerve. Data was analysed for correlation using SPSS version 20. Results: BMI has negative correlation with APB H-reflex latency and amplitude with “r” value -0.03 and -0.007 respectively. Arm length was found to be positively correlated with APB H-reflex latency and amplitude with “r” value 0.391 and 0.024 respectively. Conclusion: As BMI increases, APB H-reflex latency and amplitude decreases. With increasing arm length, APB H-reflex latency and amplitude increases. Hence, arm length and BMI should be taken into account while interpreting APB H-reflex among females to avoid misleading diagnosis.