Autonomic neuropathy is known as a complication of diabetes mellitus. Conventional electromyograpic procedure was used to diagnose diabetic neuropathy, routinely. But these procedure was useful mainly to evaluate for large myelinated fibers and was not adequate to assess the degree of autonomic nervous system involvement(small unmyelinated C-fiber).
There was a simple, reliable and non-involve test to identify unmyelinated peripheral axonal dysfunction by the sympathetic skin response(SSR). The SSR was thought to be originated from the synchronized activation of eccrine sweat glands innervated by sudomotor sympathetic fiber. In our study, SSR was measured in 41 diabetic patients and 20 normal control subjects and studied correlation with cardiovascular autonomic function test and routine nerve conduction study and electromyographic findings. The SSR responses were detected in all control group(100%0 and 17 of 41 diabetic patients(41.5%) and the latency and amplitude of SSR were not differenct between control group and diabetic patients who showed response. The responses were divided into normal(presence) or abnormal(absence). The response was absent in severe peripheral neuroapthy, especially combined axonal damage(upper extremity: x2=12.000 DF=2, p=0.02, lower extremity: x2=13.418, DF=3, p=0.00381). And the response was also absent in combined sympathetic and parasympathetic damage in cardiovascular autonomic function test(x2=6.33108, DF=1, p=0.00186). The SSR may be a valuable method in the assessment of unmyelinated axonal damage(small unmyelinated C-fiber) and autonomic involvement in conjuction with other autonomic function test in diabetic neuropathic patients.
