OUTCOMES OF PERCUTANEOUS ELECTRICAL NERVE FIELD STIMULATION COMPARED TO STANDARD MEDICAL THERAPY IN ADOLESCENTS WITH FUNCTIONAL ABDOMINAL PAIN DISORDERS

Introduction: Chronic nausea and abdominal pain are debilitating symptoms that often co-exist in children with functional abdominal pain disorders (FAPD). Standard medical therapy (SMT) includes the off-label medications, cyproheptadine and amitriptyline. While several pediatric studies have demonstrated the benefits of percutaneous electrical nerve field stimulation (PENFS) in children with FAPD, no study has compared outcomes of PENFS to SMT. We aimed to compare improvements in abdominal pain, nausea and disability using validated measures between these treatments.
Methods: The electronic medical records (demographic data and medical history) of patients aged 11-21 years who met the Rome 4 criteria for a FAPD and had been treated with 4 weeks of PENFS, cyproheptadine or amitriptyline were reviewed. Outcomes were evaluated using validated questionnaires collected as part of clinical care at baseline and follow-up within 3 months (FU) and included: Abdominal Pain Index (API), Nausea Severity Scale (NSS), and the Functional Disability Inventory (FDI).
Results: Of the 101 patients, 35% had functional dyspepsia and had IBS each while 30% had functional abdominal pain. Of these, 49 (48%) were treated with PENFS, 31 (31%) with cyproheptadine and 21 (21%) with amitriptyline and median ages in these groups were 17 (15-19), 16 (15-18) and 15 (11-16) years respectively. In all three groups, majority were females (75%, 90% and 52% respectively).
In the PENFS group, API (p=0.001), NSS (0.05) and FDI (p=0.04) were lower at FU compared with baseline. All scores decreased but were not significant in the cyproheptadine group. API scores decreased at FU in the amitriptyline group (p=0.03). Examining each outcome longitudinally, the API and NSS scores were lowest in the PENFS group. The FDI scores however, were lowest in the amitriptyline group.
Comparing outcomes between groups, API scores were significantly lower in PENFS versus cyproheptadine (p=0.04) but not between PENFS and amitriptyline (p=0.64, figure 1). The NSS scores were significantly lower in PENFS vs. cyproheptadine (p<0.001), between PENFS vs. amitriptyline (p<0.001) and in amitriptyline vs. cyproheptadine (p=0.04). The FDI scores were only lower in the amitriptyline vs. cyproheptadine group (p=0.03).
Conclusion: In children with FAPD, PENFS showed improvements in abdominal pain, nausea and disability while amitriptyline showed improvements in abdominal pain within 3 months of treatment. PENFS was more effective than SMT in reducing nausea scores within 3-month follow-up. PENFS was also more effective than cyproheptadine in improving abdominal pain scores but did not differ from amitriptyline. Amitriptyline improved disability scores more than cyproheptadine.