Objective: Antibodies reacting with the m3 subtype muscarinic acetylcholine receptor appear to be an important pathogenic factor in primary Sjögren's syndrome (pSS). As this receptor subtype is functionally important in the gastrointestinal and urinary tracts, and very little is known about the autonomic nervous system function in these organs in pSS patients, the occurrence and clinical significance of an autonomic nervous system dysfunction involving the gastrointestinal and urinary tracts were investigated.
Methods: Data on clinical symptoms attributable to an autonomic dysfunction were collected from 51 pSS patients. Gastric emptying scintigraphy and urodynamic studies were performed on 30 and 16 patients, respectively, and the results were correlated with patient characteristics and with the presence of autonomic nervous system symptoms.
Results: Gastric emptying was abnormally slow in 21 of the 30 examined patients (70%). Urodynamic findings, compatible with a decreased detrusor muscle tone or contractility were found in 9 of the 16 patients tested (56%). Various symptoms of an autonomic nervous system dysfunction were reported by 2-16% of the patients.
Conclusion: Signs of an autonomic nervous system dysfunction involving the gastrointestinal and the urinary systems can be observed in the majority of pSS patients. This high occurrence is rarely associated with clinically significant symptoms. The authors presume a role of autoantibodies reacting with the m3 muscarinic acetylcholine receptor in the elicitation of the autonomic dysfunction.