The LONG LATENCY REFLEX is an electrical response following the H reflex on stimulation of a mixed nerve. It assesses the sensory and motor pathways travelling via cortex. It helps to determine the conduction velocity within the spinal cord. LLR is clinically useful in investigating movement disorders like Parkinson's disease, Huntington's chorea. As very few Indian studies are available on LLR, the present study was undertaken to determine latency and amplitude of LLR of abductor digiti minimi of the dominant and non-dominant hand. Twenty healthy male subjects in the age group of 25–35 years were studied by stimulating ulnar nerve while the subject was maintaining 10–20% of maximum voluntary contraction of the abductor digiti minimi. A stimulus intensity of 5-10mA (submaximal) of 1 ms duration, delivered from a constant current stimulator through bipolar stimulating electrodes was used to stimulate the muscle. The latency of the first deflection from the baseline and the peak to peak amplitude of the evoked LLR responses were measured digitally using a digitalized nerve conduction/EMG/EP machine (Aleron, Recorders Medicare systems, Chandigarh, India).
Statistical analysis showed that the LLR latency of ADM of dominant hand (48.7±5.7ms, Mean± SD) was equal to the corresponding value obtained from the non-dominant hand (47.1±4.7ms). LLR amplitude of ADM of dominant hand (155.3±78μV, Mean ± SD) was also equal to the corresponding value from the non-dominant hand(144.7±49.9 μV). The height of the individual and LLR latency showed a significant positive correlation in the dominant hand (p< 0.02) and also in non-dominant hand (p<0.05).
Long latency reflex (LLR), H reflex
