Vagus nerve stimulation (VNS) offers the possibility of a unique, non-pharmacotherapy for treating behavior in PWS, Prader-Willi syndrome. A small pilot study involving three patients with PWS has shown promising results, and next steps are already underway to further investigate this possible treatment.
What is Vagus Nerve Stimulation?
VNS uses a device to stimulate the vagus nerve with electrical impulses. The vagus nerve is involved in satiety signals from the gastrointestinal system to the brain, and studies have reported weight loss in some non-PWS patients undergoing VNS, as well as altered food cravings. When activated, the VNS device sends electrical signals along the vagus nerve to your brainstem, which then sends signals to certain areas in your brain. VNS has been approved for the treatment of epilepsy and depression and researchers are currently studying VNS as a potential treatment for a variety of conditions, including multiple sclerosis, headache, pain, Alzheimer's disease and PWS.
What is the implication for PWS?
Dr. Tony Holland, professor of psychiatry at Cambridge University, is an expert in PWS research and is leading the investigation of VNS as a potential treatment for PWS. The initial VNS study in PWS was designed to investigate effects on hyperphagia. Three individuals (with PWS) underwent surgery to implant the VNS device. VNS was switched on 3 months post-implantation, with an initial 0.25 mA output current incrementally increased to a maximum of 1.5 mA as tolerated by each individual. Participants were followed up monthly.While changes to hyperphagia were not observed, unexpected improvements in maladaptive behavior were reported by two patients and their families. Two of the 3 patients and their caregivers reported consistent beneficial effects in behavior, temperament and social functioning. Based on these reports, the study took on a new aim to investigate the potential effects of VNS on behavior in PWS.
Patient Anecdotal Data
While the patients and caregivers acknowledge that VNS has not been a magical cure, 2 of the 3 patients and their caregivers do feel it has been life altering. One patient is now able to maintain a part time job that the caregiver reports would not have been possible without VNS and a second patient is now married and living independently. A third patient reported no improvements.
Next Steps
Since the initial VNS study with PWS patients, new, noninvasive VNS devices, which do not require surgical implantation, have been approved for use in Europe to treat epilepsy, depression and pain.Thanks to your support, FPWR is providing a second year of funding so Dr. Holland may complete his proof of concept study with a larger patient group using the external device with PWS patients. 6 months of baseline data has been collected with the device turned off, Dr. Holland will now turn on the device and measure the effects of the treatment.
