Autonomic dysfunction in systemic sclerosis: sympathetic overactivity and instability.

PURPOSE: This study was designed to assess the prevalence and nature of autonomic dysfunction (AD) in 34 patients with systemic sclerosis (SSc). PATIENTS AND METHODS: Patients were questioned for current symptoms possibly related to AD. Five noninvasive cardiovascular autonomic function tests and sequential plasma catecholamine estimations at rest, during standing, and during sustained handgrip were performed. Seven patients with manometrically documented esophageal involvement and high resting plasma adrenaline levels were treated with clonidine (75 to 375 micrograms/d). One month later, resting plasma catecholamine estimations and esophageal motility studies were repeated.
RESULTS: Autonomic testing revealed AD in each patient, while symptoms were experienced by 33 of them. Findings on two of the three heart rate tests and both blood pressure tests were significantly impaired as compared with those in 25 matched control subjects. Mean resting plasma adrenaline levels were 18 times higher than in 10 matched controls (p less than 0.001). Plasma catecholamine (adrenaline, noradrenaline, and dopamine) concentrations and mean arterial blood pressures fluctuated inappropriately during standing and sustained handgrip in 28 (82%) of the patients. The presence of headaches correlated significantly with sympathetic overactivity and instability (p less than 0.05). Resting plasma adrenaline concentrations correlated inversely with disease duration (p less than 0.05). Significant suppression of sympathetic overactivity and increases in resting lower esophageal sphincter pressures were observed in the seven patients treated with clonidine.
CONCLUSION: AD is extremely common in SSc. It is characterized by parasympathetic impairment and marked sympathetic overactivity, particularly in early disease. The potential role of AD in the pathogenesis of SSc deserves further study.