Cyclic vomiting syndrome (CVS) is an difficult to treat and debilitating functional gastrointestinal disorder. Majority of children and adults with CVS have concurrent severe abdominal pain and migraine-features, rendering them incapacitated during the vomiting cycle.

The vagus nerve carries signals of nausea, vomiting and pain between the brain and the gastrointestinal tract and is part of the autonomic nervous system. The autonomic nervous system appears to be in imbalance in patients with CVS during a vomiting cycle. By stimulating a branch of the vagus nerve in the outer ear, this study aims to improve symptoms and quality of life in both children and adults with CVS.

Subjects will be randomized to receive active vs sham (non-active) neurostimulation therapy for 5 days at the onset of a CVS cycle. They will then cross over to the other group (active vs sham) at the onset of the next CVS cycle. Subjects in a separate sub-study receive 6 weeks of active neurostimulation therapy (5 days/week). Pain, nausea, vomiting, anxiety, quality of life, potential side effects and overall symptom improvement will be monitored before and after therapy for the entire study.