Auricular Allodynia is Associated With Worse Outcomes in Children With Functional Abdominal Pain Disorders Using Neurostimulation.

BACKGROUND AND AIMS: Percutaneous electrical nerve field stimulation (PENFS) is a minimally invasive, nonpharmacologic approach to treat children with functional abdominal pain disorders (FAPD). Allodynia refers to pain from a stimulus that does not usually provoke pain. We aimed to characterize auricular allodynia during PENFS and associate it with outcomes.

MATERIALS AND

METHODS

We conducted a retrospective cohort study reviewing charts of patients who underwent PENFS for an FAPD. We included demographic data, medical history, and validated questionnaire responses. Allodynia was noted through physician notes of localized ear pain, soreness, or tenderness. Baseline clinical scores and PENFS outcomes were compared in patients with and without allodynia.

RESULTS

Of 219 patients with FAPD (mean age 16.2 ± 2.7 years), 79% were female, and 87% were Caucasian; 28% of patients experienced allodynia with no significant demographic differences. The most common gastrointestinal symptoms were abdominal pain (100%) and nausea (70%), and the most common FAPD diagnoses included irritable bowel syndrome (58%) and functional dyspepsia (54%). Of the 93 total visits with allodynia, 44% of the visits had patients report allodynia once and 34% twice. Common interventions included placing <four of the usual leads (19%) and early device removal (10%). Patients with allodynia had significantly greater Abdominal Pain Index, pain catastrophizing, Functional Disability Inventory, and insomnia scores (p < 0.05) at treatment completion than did those without allodynia.

CONCLUSION

Allodynia in patients with FAPD who underwent PENFS had worse clinical outcomes. Excitation thresholds of rapidly conducting Aβ fibers in the ear are lower than those of nociceptive slowly conducting Aδ and C fibers. Patients with allodynia may require adjustment of nerve fiber stimulation to improve outcomes.