Sympathetic skin response impairment: A good predictor of bone loss in electrical burn victims

Burn victims are reported to have more possibility of bone loss in acute phase of injury partly due to sympathetic dysfunction and catecholamine increase beside other hypermetabolic responses. These patients are also prone to autonomic neuropathy and sympathetic skin response (SSR) impairment. We aim to investigate the correlation between SSR in the acute phase and bone mineral density (BMD) parameters in electrical burn patients and determine whether the SSR parameter in initial weeks of the event is a good predictor of bone loss in long term.

Sixty two individuals exposed to low voltage(<1000 V) electrical current were invited to a cohort study. The SSR was recorded from their four limbs in 2-5 weeks after injury. Then, dual X-ray absorptiometry (DXA) was done to measure their BMD, T-score and Z -score, 9-12 months later. The correlation between SSR parameters in acute phase and DXA indexes was evaluated using Spearman test. A Roc curve was charted to point out a cut-off value for SSR amplitude and latency in respect to T-score to predict the subsequent bone loss.

All the patients were male with a mean age of 34.09 years. Biphasic SSR parameters showed a significant correlation with lumbar BMD in a confidence interval of 99.9%. SSR amplitude threshold of 293.75 μV and latency of 2.15 s had a 100% sensitivity and 94% and 83% specificity respectively for predicting the bone loss (T-score<-1) in long term. The area under Roc curve was 0.94 and 0.99 in terms of SSR amplitude and latency.

SSR recorded in the first few weeks after electrical injury is a good predictor of bone loss in long term, so we recommend this test as a guide for screening the patients at risk for osteoporosis in electrical burn and formulating the preventive measurements.