Patients with idiopathic rapid-eye-movement sleep behavior disorder show normal gastric motility assessed by the 13C-octanoate breath test.

Background: Delayed gastric emptying is a non-motor symptom of Parkinson's disease. Few data exist on gastric emptying in early-stage Parkinson's disease. In idiopathic rapid-eye-movement sleep behavior disorder, a presumable pre-motor stage of Parkinson's disease, gastric emptying has not yet been investigated. Methods: Twenty healthy controls, 13 patients with idiopathic rapid-eye-movement sleep behavior disorder, and 39 patients with Parkinson's disease patients underwent standardized testing for gastric emptying with the (13)C-octanoate breath test. Results: Gastric emptying was significantly delayed in drug-naive (P <. 001) and in treated Parkinson's disease patients (P < .001), but normal in patients with idiopathic rapid-eye-movement sleep behavior disorder. Conclusions: Our study confirms delayed gastric emptying in drug-naive, early-stage Parkinson's disease. Normal gastric emptying in idiopathic rapid-eye-movement sleep behavior disorder might be explained by the fact that neurodegenerative changes in structures modulating gastric motility are not severe enough to cause a functional deficit that can be detected by the (13)C-octanoate breath test. (C) 2011 Movement Disorder Society