Sympathetic skin response in scleroderma, scleroderma overlap syndromes and inflammatory myopathies

Sympathetic skin response (SSR), a noninvasive method for evaluation of the autonomic nervous system, was studied in 57 patients with various connecti ve tissue disorders: scleroderma, dermatomyositis, polymyositis, scleromyos itis and unclassified collagenoses. The patients were divided into three ma in groups: scleroderma (SSc), myositis or other inflammatory myopathy (M) a nd scleromyositis (ScM). The aim of the study was to detect abnormalities o f the SSR in the connective tissue diseases, to define the pattern for each group and to evaluate the usefulness of SSR in detection of subclinical im pairment of sympathetic cholinergic function. In the myositis group, an abn ormal SSR was found in 88% of patients; the main abnormality was absence of the response from the lower limbs tin 50% of patients). In scleroderma, th e SSR was abnormal in 77% of patients, consisting mainly of absence of the response from the lower limbs, whereas responses from the upper limbs were normal. In scleromyositis, the SSR was abnormal in 80% of patients, the mos t frequent finding was an increase in latency in one limb. The SSR changes were most pronounced in connective tissue disorders with myositis or inflam matory myopathy. The SSR, although nondisease-specific, because of its sens itivity, seems to be useful in the assessment of the abnormalities of the a utonomic nervous system in scleroderma and inflammatory myopathies. The stu dy showed a very high prevalence of autonomic nervous system dysfunction in connective tissue diseases associated with myopathy or myositis, displayin g no clinical symptoms of autonomic system involvement.