Demonstration of autonomic dysfunction following brachial plexus injury using Quantitative Sudomotor Axon Reflex Test [QSART]

Objective: To objectively document autonomic dysfunction, in the affected arm, with Brachial Plexus injury, using Quantitative Sudomotor Axon Reflex Test (QSART). Method: Patients with brachial plexus injury presenting to the neurosurgical OPD from August 2013 to November 2014 were included in the study. The QSART was performed to each patient with prior informed consent detailing the procedure. Twenty patients with brachial plexus injuries were included in the study. The injuries were grouped as preganglionic and postganglionic injuries based on clinical findings, Nerve conduction studies and Magnetic Resonance imaging findings. The results were analysed with appropriate statistical tests to look for any significant difference between the affected and normal arm. Result: The study included 20 patients. The ages ranged from 15 years to 50 years. Out of the 20 subjects 1 was female and the rest 19 were males. Seven (35%) of the injuries were complete and 13(65%) were incomplete. All patients had preganglionic injuries. There was no evidence of any statistically significant difference between the affected and normal arm for total sweat volume (p = 0.20) and latency period (p = 0.42). However the average mean values for the same were lower in the affected arm as compared to the normal. The baseline sweat output (p = 0.010) however was significantly lower in the affected arm as compared to the normal arm. Conclusion: QSART has demonstrated reduced baseline sweat output in the affected arm in patients with brachial plexus injury. This indicates the presence of autonomic dysfunction in the injured arm.