Factors predicting outcome after anterior neurectomy in patients with chronic abdominal pain due to anterior cutaneous nerve entrapment syndrome (ACNES).

BACKGROUND: Chronic abdominal pain due to anterior cutaneous nerve entrapment syndrome may require surgery to provide long-term pain relief in up to 70% of patients. Factors predicting outcome after an anterior neurectomy are unknown. The aim of the study is to identify factors associated with treatment failure to possibly allow for optimizing patient counselling and selection. METHODS: Characteristics of anterior cutaneous nerve entrapment syndrome patients who were unresponsive to nonsurgical therapies and underwent an anterior neurectomy in a tertiary referral center from 2011 to 2016 were analyzed. Treatment failure was defined as <50% pain reduction using a numeric pain rating scale (numeric pain rating score 0-10) approximately 2 months postoperatively. A prediction model based on a multivariate regression analysis was tested for its discriminative value. RESULTS: A total of 495 patients (78% female, median age 40 years, range 8-83) undergoing an anterior neurectomy were eligible for analysis. Pain medication use (odds ratio 1.84, P = .027, confidence interval 1.07-3.17), abdominal surgery in the past (odds ratio 1.85, P = .026, confidence interval 1.08-3.18), the presence of paravertebral tender points at exit points of intercostal nerves (odds ratio 2.58, P = .003, confidence interval 1.39-4.80), and failure to favorably respond to a diagnostic rectus sheath block (odds ratio 3.74, P = .000, confidence interval 3.74 - 7.10) were identified as factors predicting surgical failure. However, a prediction model including these 4 factors had poor accuracy with an area under the curve of 0.64 (confidence interval 0.58-0.70). CONCLUSION: The present study identified risk factors associated with treatment failure that are useful in counseling anterior cutaneous nerve entrapment syndrome patients prior to a surgical intervention.

Adding steroids to lidocaine in a therapeutic injection regimen for patients with abdominal pain due to anterior cutaneous nerve entrapment syndrome (ACNES): a single blinded randomized clinical trial.

Background and aims Anterior cutaneous nerve entrapment syndrome (ACNES) may result in chronic abdominal pain. Therapeutic options include local injection therapy. Data on the efficacy of adding corticosteroids to these injections is lacking. Methods Patients ≥18 years with ACNES were randomized to receive an injection of lidocaine with (LC-group) or without (LA-group) the addition of methylprednisolone into the point of maximal abdominal wall pain. Pain was recorded using a numeric rating scale (NRS: 0-10) and a verbal rating scale (VRS: 0=no pain, 5=unbearable pain) at baseline and 6 weeks after the start of a bi-weekly injection regimen consisting of a total of three injections. A minimal 50% reduction on NRS and/or two points on VRS were considered successful responses. Results Between February 2014 and August 2016, 136 patients (median age 46 year, range 18-79, 75% females) were randomized (68 vs. 68). The proportion of patients demonstrating a successful response after 6 weeks did not significantly differ between groups (LA 38%, LC 31%, p=0.61). At 12 weeks, the number of patients still experiencing a minimal 50% pain relief had decreased but no group difference was observed (LA 20%, LC 18%, p=0.80). Minor side effects included temporary increase of pain, tenderness at injection sites or transient malaise (LA23/68, LC 29/68, p=0.46). Conclusions Adding corticosteroids to a lidocaine does not increase the proportion of ACNES patients with a successful response to injection therapy. Lidocaine alone can provide long term pain relief after one or multiple injections, in approximately 1 of 5 patients.