Occupational or extrinsic stimulation factors and initial signs of progressive systemic sclerosis.

Forty-eight patients with progressive systemic sclerosis (PSS) (man-woman ratio, 7:41) were studied, and detailed questionnaires were used to clarify the relationship between occupational stresses and the initial signs of PSS. All of the patients were right-handed. Raynaud sign was seen in 37 of the 48 patients (77.1%) as the predominant initial sign of PSS, and it first was noticed on the right index and middle fingers. Three sets of extrinsic aggravating factors, vibration stress, fine hand work with mental stress, and exposure to cold, were believed to be related closely to the development of the initial signs because the initial signs appeared after long-term exposure to the extrinsic factors.