Influence of age and gender on the function of postganglionic sympathetic sudomotor axons

The quantitative sudomotor axon reflex test (QSART) is an autonomic function test to evaluate the function of postganglionic sympathetic sudomotor axons. The QSART is used for research and in clinical assessment of various neurological diseases, but few studies have assessed the influence of age, gender and reported a normative range. We assessed the influence of age and gender on QSART parameters.

We recruited 61 healthy volunteers (41 men and 20 women) after obtaining written informed consent. The QSART was recorded as per standard protocol after iontophoretic stimulation (using acetylcholine) for 5 minutes. We analysed the sweat response to obtain total sweat production, rate of sweat production and latency time from the start of stimulation to sweat response. We assessed these parameters in the right medial forearm, right proximal leg, right distal leg and right proximal foot.

Men had significantly higher evoked sweat volume and sweat latency period compared to women. A positive correlation was observed between age and evoked total sweat volume. An inverse correlation was noted between age and evoked sweat latency period.

Postganglionic sudomotor function increased significantly with age. Men had significantly higher sweat volume suggesting sympathetic predominance. These results might help establish normative data for the Indian population.