Transcutaneous vagus nerve stimulation (t-VNS): A novel effective treatment for temper outbursts in adults with Prader-Willi Syndrome indicated by results from a non-blind study
Four hours of daily ear-clip vagus stimulation sharply cut temper outbursts in adults with Prader-Willi syndrome, but half the dose lost the benefit.
01Research in Context
What this study did
Manning et al. (2019) tested a small clip that buzzes gentle pulses on the ear. The clip is called transcutaneous vagus nerve stimulation, or t-VNS.
Five adults with Prader-Willi syndrome wore the clip four hours every day for nine months. Staff counted temper outbursts each day to see if the buzzing helped.
What they found
Four of the five adults had far fewer temper outbursts while using the full four-hour dose. When the daily time was cut to two hours, outbursts quickly returned to old levels.
How this fits with other research
Libero et al. (2016) tried an older, implanted vagus device in three adults with PWS. They saw mild gains in behavior, but the effect on eating was unclear. Manning’s team used a skin-level clip and saw larger, clearer drops in outbursts, showing the newer method may work better.
Klusek et al. (2022) found that child outbursts wear caregivers down. Because t-VNS calms outbursts, it could also ease family stress.
Smit et al. (2019) showed that adults with PWS have poor impulse control and odd skin-conductance patterns. t-VNS did not fix those lab scores, yet real-life outbursts still fell, so the clip likely works through a different pathway.
Why it matters
If you serve adults with PWS who have daily tantrums, t-VNS offers a low-risk option you can try now. No surgery is needed; the clip goes on the ear. Start with the full four-hour daily dose, track outbursts with staff or parents, and watch for a drop within weeks. If gains appear, keep the hours high—cutting dose in half brought behaviors back in this study.
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02At a glance
03Original abstract
Temper outbursts are a severe problem for people with Prader-Willi Syndrome (PWS). Previous reports indicate that vagus nerve stimulation (VNS) may reduce maladaptive behaviour in neurodevelopmental disorders, including PWS. We systematically investigated the effectiveness of transcutaneous VNS (t-VNS) in PWS. Using a non-blind single case repeat measures modified ABA design, with participants as their own controls, t-VNS was evaluated in five individuals with PWS [three males; age 22–41 (M = 26.8)]. After a baseline phase, participants received four-hours of t-VNS daily for 12 months, followed by one month of daily t-VNS for two-hours. The primary outcome measure was the mean number of behavioural outbursts per day. Secondary outcomes included findings from behavioural questionnaires and both qualitative and goal attainment interviews. Four of the five participants who completed the study exhibited a statistically significant reduction in number and severity of temper outbursts after approximately nine months of daily four-hour t-VNS. Subsequent two-hour daily t-VNS was associated with increased outbursts for all participants, two reaching significance. Questionnaire and interview data supported these findings, the latter indicating potential mechanisms of action. No serious safety issues were reported. t-VNS is an effective, novel and safe intervention for chronic temper outbursts in PWS. We propose these changes are mediated through vagal projections and their effects both centrally and on the functioning of the parasympathetic nervous system. These findings challenge our present biopsychosocial understanding of such behaviours suggesting that there is a single major mechanism that is modifiable using t-VNS. This intervention is potentially generalizable across other clinical groups. Future research should address the lack of a sham condition in this study along with the prevalence of high drop out rates, and the potential effects of different stimulation intensities, frequencies and pulse widths.
PLoS ONE, 2019 · doi:10.1371/journal.pone.0223750