Rumination and vomiting in Prader-Willi syndrome.

Inability to vomit has been cited as characteristic of Prader-Willi syndrome (PWS). Although post-prandial vomiting after gastric by-pass surgery has been reported, neither vomiting under "typical" circumstances or rumination have been described. Prompted by the discovery of several cases of vomiting and rumination, a questionnaire was sent to members of the PWS Association. Approximately 36% (113/313) of affected individuals reportedly experienced at least one episode of vomiting. Induced vomiting was unsuccessful in 9 of 14 cases in whom results were known. However, no complications of Ipecac were reported. We suggest that there is an alteration in the physiologic set-point at which vomiting occurs, leading to a decreased propensity to vomit. Liberal and strict definitions of rumination yielded 15.7% and 10.2% positive responses, respectively. Rumination was associated with a history of vomiting. Enamel deterioration consistent with rumination has been observed, and such changes should be looked for in all PWS children. In several instances, rumination was found to decrease when very strict weight control was lessened. Certain individuals may ruminate under too strict a weight control program, and weight control goals should be evaluated to achieve a reasonable compromise between ideal weight and obesity. Vomiting and rumination do not rule out the diagnosis of PWS.