Sympathetic skin responses in patients with bronchial asthma

Asthma is a chronic inflammatory disease of the airways. Parasympathetic hyperactivity results in bronchoconstriction and despite the increase in sympathetic activity, this increase fails to overcome bronchoconstriction. Sympathomimetic drugs are used in the treatment of asthma. Therefore, autonomic nervous system involvement and sympathetic dysfunction were thought to be present in asthma. In this study, we aimed to investigate the role of the sympathetic nervous system in the pathogenesis of bronchial asthma. Sympathetic skin responses (SSR) from hand regions of 39 asthma patients and 20 healthy controls similar in age- and gender were recorded with right median nerve electrical stimulation. In 7 of 39 patients, sympathetic skin responses were recorded 2 times in non-drug and drug groups. One of these patients was in drug-attack group during the 2nd study and others were in non-drug-attack group. A total of 46 SSRs were obtained from 15 non-drug group patients, 8 drug-attack group patients and 23 non-drug-attack group patients. No statistically significant difference was detected in SSR amplitudes between control group and all the patients and the other 3 sub-groups (non-drug, drug-attack, non-drug-attack). A statistically significant difference was found between control group and all patients and non-drug-attack only in comparison of SSR latencies. However, SSR latency measurement has been reported not as reliable as amplitude, so based on the latency difference, discussing the existence of pathology in sympathetic nervous system of patients with asthma is thought not to be reliable.SSRs, recorded from hands of asthma patients, were insufficient to demonstrate the dysfunction of sympathetic nervous system. Therefore, with combined studies of tests showing functions of both the parasympathetic and sympathetic nervous system performed in much more patients, the role of the autonomic nervous system in the etiopathogenesis of this disease could be better explained.Key Words: Asthma, Sympathetic nervous system, Sympathetic skin responce