Autonomic dysfunction with postural hypotension and parasympathetic prevalence in Sjögren's syndrome

Introduction: Sjogren's syndrome is characterized by xerophthalmia and xerostomia, with impaired salivary and lachrymal secretions; frequent systemic complaints as asthenia, fatigue and postural instability point to a possible involvement of autonomic nervous system. Methods: Present study investigated autonomic function in 20 consecutive SS women, aged 55 ± 11 years, examined for autonomic nervous system function by computing the heart rate and blood pressure changes with a Finapres device during cardiovascular tests and by performing spectral analysis of heart rate variability in order to calculate low frequency and high frequency power at rest and during tilt test. Results: 10 Sjögren's syndrome patients showed postural hypotension associated to a marked tachycardia; 13 cases showed one or more cardiovascular tests indicative of an high parasympathetic tone; heart rate variability analysis demonstrated significantly reduced sympathetic tone (low frequency 35.77 ± 19.97 vs. 51.82 ± 16.9 n.u., p < 0.05), a reduced low frequency/high frequency ratio (1.39 ± 1.49 vs. 2.72 ± 2.24, p < 0.05), with a low frequency/high frequency ratio ≤ 1 in 8 cases. Conclusions: Sjögren's syndrome patients show an unbalanced autonomic nervous system, characterized by a clear parasympathetic prevalence at rest, with a transient postural hypotension and an early orthostatic sinus tachycardia; this autonomic pattern should be regarded as a result of a systemic adaptive response to an impairment of autonomic control of the exocrine glands.