Cyclic Vomiting Syndrome

This exploratory study will determine if there are differences in cortical excitability between patients suffering from cyclic vomiting syndrome (CVS) and healthy control subjects, as assessed by a non-invasive method of brain stimulation (Transcranial Magnetic Stimulation, TMS).

Cyclic vomiting syndrome (CVS) is a fairly common disorder characterized by relentless episodes of vomiting followed by return to baseline health.The majority of children with CVS have concurrent severe abdominal pain and migraine-features, causing significant disability during the attacks. There are very few non-drug treatment options for CVS. Many patients are treated with antidepressants that are often ineffective and may cause serious side effects. Emergency room visits and hospitalizations for patients with CVS is extremely high and the syndrome has an immense impact on quality of life. Safe and effective, non-pharmacological therapies for children with CVS are greatly needed. Nausea, vomiting and gastrointestinal pain is modulated by the vagus nerve, an important regulator of the autonomic nervous system. The vagus communicates signals between the gastrointestinal tract and the central nervous system. Many studies indicate that vagal nerve stimulation is effective for various pain and vomiting conditions. Recent studies show that vagus nerve signaling is impaired in children with CVS. Researchers have demonstrated safety and efficacy of auricular percutaneous electrical nerve field stimulation (PENFS) targeting the vagus nerve in a small study of children with CVS. The aim of the current study is to investigate the effects of non-invasive PENFS on CVS episode frequency, duration and severity compared to a sham device in a randomized clinical trial.

Disorders of gut-brain interaction (DGBI) affect up to 25% of U.S. children. Patients often suffer from disabling, multisystem comorbidities that suggest a common root (sleep disturbances, fatigue, anxiety, etc). Yet, DGBI are defined and treated based on GI symptom origin (cyclic vomiting, dyspepsia, irritable bowel) rather than underlying pathophysiology. Many patients manifest comorbidities suggesting an underlying autonomic nervous system (ANS) dysregulation (palpitations, dizziness, cognitive dysfunction). Unfortunately, due to common features of anxiety and visceral hyperreactivity and lack of obvious pathology, children with DGBI are frequently diagnosed with psychosomatic or 'benign, functional disorders' and treated with empiric antidepressants despite lack of scientific support and risks of serious side effects. Little is known about the underlying brain-gut mechanisms linking these comorbidities. A lack of targeted treatment options naturally follows the paucity of mechanistic data. A dysregulated ANS response circuit via brainstem nuclei is linked to visceral hypersensitivity. As the team's prior research has shown, ANS regulation can be non-invasively measured via several validated indices of cardiac vagal tone. Using the novel vagal efficiency (VE) metric, the investigators have demonstrated inefficient vagal regulation in cyclic vomiting syndrome and pain-related DGBI and that low VE predicts response to non-invasive, auricular percutaneous electrical nerve field stimulation (PENFS) therapy. PENFS targets brainstem vagal afferent pathways and, along with brain-gut interventions such as hypnotherapy, are the only therapies currently proven effective for pediatric DGBI. Individualizing neurostimulation based on sensory thresholds while assessing dynamic ANS reactivity offers a path towards personalized medicine using the most effective therapies to date. This proposal will test the feasibility of an ANS tracking software in assessing real-time, autonomic regulation and providing individualized neurostimulation in children with nausea/vomiting and ANS imbalance.