The goal of the VNS4PWS clinical study is to test the efficacy, safety, and acceptability of transcutaneous vagus nerve stimulation (tVNS) treatment in people with PWS.

The main questions the VNS4PWS study seeks to answer are: (1) is tVNS treatment safe in people with PWS, (2) is tVNS treatment acceptable to people with PWS, and (3) is tVNS an effective treatment to reduce temper outbursts in people with PWS. Participants will wear the tVNS device daily for 4 hours over a period of 9 months. Two different doses of tVNS will be compared. During the final three months of the trial, the effect of stopping treatment will be studied. After the first year of the study, participants will have the opportunity to continue on to a 1-year open label extension period during which active tVNS treatment will be resumed.

Inclusion Criteria:

1. Genetically proven diagnosis of PWS.
2. Age 10-40 years.
3. History in the last six months of an average of at least two temper outbursts per week.
4. Able to comply with requirements of study and provide consent or assent; If consent is to be provided by the participant's guardian, same applies to the guardian.
5. Concomitant use of psychiatric medication is allowed; participant must be on a stable dose 90 days prior to screening with no plans for dose modification during the course of the study.
6. Concomitant use of psychotherapy/counseling is allowed. Therapies for mental health or behavior challenges, including applied behavior analysis (ABA) are also allowed; however, participant must be on a stable regimen 90 days prior to screening with no plans for modification during the course of the study.
7. Living with family or in another setting with family members or staff willing to support the participant and the required data collection.
8. Agree to share tVNS patient application compliance and daily temper outburst data with the sponsor.
9. Access to cellular data or Wi-Fi.
10. Participant and caregiver speak American English as first language or are fluent in American English.

Exclusion Criteria:

1. Positive pregnancy test at screening, baseline, or at any point in the study.
2. Evidence of active or recent unstable serious mental illness, including, psychosis, mania, severe depression, or suicidality.
3. Moved to present residential placement in last three months or less.
4. Likely move in residential placement during the course of the study.
5. Cardiac abnormalities including medically documented history of cardiac disease or cardiac arrhythmia, documented resting heart rate ≤ 50 beats per minute (BPM); or history of 2° type 2 or 3° heart block on electrocardiogram (ECG).
6. Evidence of clinically significant abnormalities of blood, liver, or kidney function from clinical safety laboratory assessments as determined by the Site Investigator.
7. History of blood clot, pulmonary embolism, or deep vein thrombosis.
8. Prior diagnosis of epilepsy or currently active seizures.
9. Current enrollment in the active phase of different clinical trial or interventional study.
10. Current use of hearing aids or implantable medical devices including implanted vagus nerve stimulation (iVNS) device, implanted cardiac pacemaker, implanted cardiac defibrillator, cochlear implants, cerebral shunt or cardiac implantable electrical devices.
11. Presence of dermal abnormalities at the stimulation site that would interfere with the ability of the tVNS device to function properly.
12. Presence of an allergy to titanium, titanium-iridium, thermoplastic elastomers, perfluoroethylene propylene, or polyurethane elastomers, or components of / preservatives present in the device electrode cream (Ceteareth-20, Propylene Glycol, Bentonite, Polysorbate 20, Phenoxyethanol, Ethylhexylglycerin).
13. Severe, untreated sleep apnea, as self-reported by subject or caregiver or suspected by Site Investigator.
14. Subject is, in the opinion of the Investigator, not suitable to participate in the study.