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Parasympathetic failure does not contribute to ocular dryness in primary Sjögren's syndrome
P J Barendregt1, A H van Den Meiracker, H M Markusse
1Department of Rheumatology, Zuiderziekenhuis, Rotterdam, the Netherlands.
Objective:
To investigate the sympathetic and parasympathetic cardiovascular function in primary Sjögren's syndrome (SS) and to investigate the possible relation with ocular dryness.
Methods:
41 (40 women) patients with primary SS, mean age 50 years (range 20-80) with a mean disease duration of eight years (range 1-30), were studied. In each patient direct arterial blood pressure (BP), heart rate (HR) and respiration were measured continuously for two hours. The function of the autonomic circulatory regulation was evaluated by measuring the heart rate response to deep breathing (6 cycles/min) and by means of the Valsalva manoeuvre and the responses of BP, HR and plasma noradrenaline (norepinephrine) concentrations to a 10 minute 60 degree head up tilt test. Pupillography was done to evaluate ocular autonomic function.
Results:
The HR-Valsalva ratio was abnormal in 24% of the patients, and the HR variability during forced respiration was abnormal in 56% of the patients. The HR responses to both the Valsalva manoeuvre and deep breathing, as indicators of parasympathetic function, were abnormally low in 6 of 41 (15%) patients. In only two patients the decrease in systolic BP in response to the head up tilt test, as indicator of sympathetic function, was more than 20 mm Hg. However, increment of plasma noradrenaline concentration during head up tilt test and the overshoot of BP in phase IV of the Valsalva manoeuvre, as indicators of sympathetic function, were normal in both patients. Thus, no evidence for sympathetic dysfunction was found, whereas evidence for parasympathetic failure occurred sometimes. Autonomic pupillary function in patients with primary SS and healthy controls, as well as the Schirmer test in patients with or without evidence for parasympathetic dysfunction as based on the results of the Valsalva and deep breathing tests, were not significantly different.
Conclusion:
Parasympathetic, but not sympathetic dysfunction seems to occur in a subgroup of primary SS. Results show that this does not necessarily contribute to the typical ocular dryness in this condition.