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.

Cyclic vomiting syndrome (CVS) is a disorder of gut-brain interaction characterized by severe, stereotypical and disabling episodes of intense nausea and vomiting, lasting anywhere from 2 hours to 7 days. The disorder is more prevalent than commonly recognized and is estimated to occur in 1.9% of children. The medical costs for the diagnosis and treatment of CVS are immense and quality of life is markedly affected and worse in children with CVS compared to other gut-brain disorders.

About 80% of patients with CVS suffer from concurrent migraine headaches or abdominal migraines during the episodes. Therapies are therefore targeted both towards both nausea and vomiting and aggressive pain control. Therapies are empiric, and response is often variable with numerous patients still requiring Emergency Room visits or hospital admissions. Tricyclic antidepressants are traditionally the most commonly used "off-label" drugs for children with CVS. These drugs may cause serious side effects, and are frequently discontinued due to intolerable adverse effects. Most recent CVS treatment guidelines in fact call for use of these antidepressants only in refractory cases and instead, increased use of non-pharmacological interventions in all children with CVS. Safer and more effective treatments for children with CVS are much needed. Currently, there are no FDA-approved drugs for the treatment of CVS in children.

The mechanisms underlying CVS remain unclear but there is emerging consensus of altered brain-gut neurocircuitry and autonomic nervous system imbalance. Autonomic abnormalities are previously documented in both children and adults with CVS. Researchers have recently demonstrated significantly altered dynamic, cardiac vagal function in children with CVS compared to age and size matched healthy controls, supporting the use of interventions that target vagal signaling.

Interventions targeting the underlying autonomic imbalance such as auricular vagal nerve stimulation are likely targeting the underlying autonomic imbalance via stimulation of the auricular branch of the vagus in the outer ear. The ear is innervated by several cranial nerves including the vagus (CN X) which projects directly to brainstem nausea and vomiting centers. Stress and elevated sympathetic nervous system activity may contribute to initiation of vomiting in CVS patients and therapy via vagal modulation may alter these signals and prevent episodes.

Non-invasive, auricular neurostimulation using the percutaneous electrical nerve field stimulation (PENFS) device has been demonstrated effective for gastrointestinal pain in a randomized, sham controlled clinical trial. More recently, PENFS was demonstrated effective in an open-label, prospective pilot study of 30 children with drug-refractory CVS. There was a significant improvement in both frequency and duration of CVS episodes from baseline (p<0.0001). Notably, a positive effect on quality of life was demonstrated at long-term follow-up after only 6 weeks of therapy. At 6 months follow-up, 80% demonstrated at least 50% improvement in either frequency or duration of episodes with a median response duration of 113 days. Importantly, 100% of these patients were satisfied with the treatment and no serious side effects were reported. Auricular neurostimulation thus modulates autonomic nervous system balance, thereby improving nausea and vomiting presumably by altering vagal signaling with secondary effects of improving quality of life.

The aim of this study is to further investigate the efficacy of auricular neurostimulation using PENFS in a randomized, sham controlled study design in a large cohort of children with CVS. Children ages 5-18 years, evaluated at Children's Wisconsin hospital gastroenterology clinic and meeting formal criteria for CVS based on 2025 NASPGHAN guidelines may be eligible to participate. Subjects will be randomized 2:1 to receive 5 consecutive weeks of active or sham PENFS therapy in a blinded fashion. Subjects will be followed for 12 months after completion of therapy.

Inclusion Criteria:

• Episodic vomiting that meet criteria for CVS based on the 2025 NASPGHAN guidelines for diagnosis of pediatric CVS
• English-speaking
• Lack of other explanation for vomiting
• Intact external ear that is free of infection or severe dermatological conditions
• Stable stable vital signs for their respective age
• No currently implanted electrical device
• Family able to accurately describe symptoms and number of vomiting episodes
• At least 2 vomiting episodes during the 6 months prior to enrollment

Exclusion Criteria:

• Medically complex children or those who take a medication or suffer from another active disease that explain symptoms
• Children or their parents who have significant developmental delay
• Participants diagnosed with alternate conditions that explains their symptoms after undergoing medical workup per standard of care
• Patients with findings of active disease such as intestinal malrotation, peptic ulcer disease, H.pylori gastritis, celiac disease, inflammatory bowel disease, allergic disorders, hydronephrosis, metabolic disorder or any other active chronic condition or medication that may cause of vomiting
• Patients who are treated with a new drug affecting the central nervous system in the 4 weeks prior to enrollment
• Pregnancy
• Severe cardiopulmonary diseases such as chronic obstructive pulmonary disease (COPD) or coronary artery disease
• Current chronic marijuana use defined as marijuana use > 2 times per week over the last 6 months prior to study enrollment
• Previously treated with a PENFS device

De-identified IPD such as patient reported outcome survey data may be shared with other researchers upon request

End of data collection (12/2028) through following year (12/2029)

Other investigators may access de-identified patient reported outcome survey data upon request. Data would be shared if permitted by IRB by exporting de-identfied data from Redcap database.

Research coordinator