Cyclic vomiting associated with excessive dopamine in Riley-day syndrome.

Goals: To analyze the neurochemical profile during the recurrent attacks of nausea and vomiting in patients with Riley-day syndrome.
Background: One of the most disabling features of patients with Riley-day syndrome are recurrent attacks of severe nausea/retching/vomiting accompanied by hypertension, tachycardia, and skin flushing, usually triggered by emotional or other stresses.
Study: We monitored blood pressure and heart rate and measured plasma catecholamines during typical dysautonomic crises triggered by emotionally charged situations. For comparison, measurements were repeated at follow-up after the symptoms had resolved and the patients were feeling calm and well.
Results: During a typical attack, patients were hypertensive and tachycardic. In all patients, circulating levels of norepinephrine (P < 0.002) and dopamine (P < 0.007) increased significantly.
Conclusions: Activation of dopamine receptors in the chemoreceptor trigger zone may explain the cyclic nausea/retching/vomiting of patients with Riley-day syndrome.