This study is an open-label, real world study that included 11–19 years olds with functional abdominal pain requiring PENFS as part of their standard care. A water Load Symptom Provocation Task (WL-SPT) before and after four weeks of treatment was done to test changes in evoked pain. Validated questionnaires to assess abdominal pain, gastrointestinal symptoms, sleep, somatic symptoms, and physical and psychological functioning were assessed before and after treatment and 6-12 months post treatment. Actigraphy was used to measure daily sleep–wake patterns.

1. 60% of patients in the study had failed medications.
2. The average duration of symptoms before treatment was 27.5 months.
3. 90% met criteria for functional dyspepsia.

Post-PENFS treatment

1. Abdominal pain improved from baseline and continued to be statistically significant at 6-12 months post treatment based on the abdominal pain index (API), p<0.0001.
2. Pain intensity immediately post Water Load-SPT was lower compared to pre-treatment (p = 0.004) but not different at 5 and 10 min.
3. Nausea improved from baseline and continued to be statistically significant at 6-12 months post treatment based on the nausea severity scale (NSs), p=0.001.
4. Functional disability improved from baseline and continued to be statistically significant at 6-12 months post treatment based on the functional disability index (FDI), p<0.0001.
5. Pain catastrophizing improved from baseline and continued to be statistically significant at 6-12 months post treatment based on the pain catastrophizing scale for children (PCS-C), p=0.001.
6. Anxiety improved from baseline and continued to be statistically significant at 6-12 months post treatment based on the Screen for Child Anxiety-Related Emotional Disorders (SCARED), p<0.03.
7. Patients reported a significant decrease in sleep-related impairments (PROMIS-SRI, p = 0.005) and disturbances (PROMIS-SD), p = 0.01.
8. Actigraphy measures of sleep onset latency showed a significant decrease from week 1 to week 4 of PENFS (p = 0.03), but other actigraphy variables did not change.
9. There were no significant adverse events.

Significance

1. PENFS appeared to blunt the increase in visual analogue scale pain intensity seen immediately after Water Load-SPT
2. The study shows for the first time that PENFS is associated with changes in mechanosensitivity and improvements in sleep, and psychological factors like catastrophizing and anxiety.
3. The changes in abdominal pain, nausea, and psychological measures were also sustained for 6–12 months post-treatment.