Bilateral distribution of anterior cutaneous nerve entrapment syndrome (ACNES): are clinical features and outcomes comparable to unilateral ACNES?

Abstract

Mirror-image pain may occur in the presence of a one-sided peripheral nerve lesion leading to a similar distribution of pain on the contralateral side of the body ("mirrored"). Anterior cutaneous nerve entrapment syndrome (ACNES) is a neuropathic pain syndrome due to entrapment of terminal branches of intercostal nerves T7-12 in the abdominal wall and sometimes presents bilaterally. This study aims to address specifics of bilateral ACNES and to determine potential differences in clinical presentation and treatment outcomes when compared with the unilateral form of ACNES. Electronic patient files and questionnaires of a case series of patients who were evaluated for chronic abdominal wall pain in a single center were analyzed using standard statistical methods. Between June 1, 2011 and September 1, 2016, 1116 patients were diagnosed with ACNES, of which a total of 146 (13%) with bilateral ACNES were identified (female, n = 114, 78 %; median (range) age 36 (1181) years). Average NRS (Numeric Rating Scale; 0-10) scores were similar (median (range) NRS scores 6 (0-10) although peak NRS scores were significantly higher in the bilateral group (9 (5-10) vs 8 (2-10); p=0.02). After a median of 26 months (1-68), the proportion of patients with bilateral ACNES reporting treatment success was 61%. One in eight patients with ACNES has bilateral abdominal wall pain. Characteristics are similar to unilateral ACNES cases. Further studies aimed at underlying mechanisms in mirror image pain pathogenesis could provide a more targeted approach in the management of this neuropathic pain.