Case: A 29 year-old female with history of multiple ED visits presents for chronic abdominal pain. Previous workups all negative including CT imaging and EGD/colonoscopy. Vital signs are normal. Exam is notable for point tenderness to LLQ, not improved with pain medication. Repeat labs and CT negative for acute intra-abdominal abnormality. Further physical exam notable for positive Carnett’s test.
Definition: Abdominal Cutaneous Nerve Entrapment Syndrome (ACNES) is defined as entrapment of cutaneous branches of lower intercostal nerves at lateral border of rectus abdominis muscle. These branches make two 90 degree turns, travelling in fibrous sheaths along their course, and at these sharp angles the nerves are susceptible to entrapment.
Epidemiology: Prevalence of up to 2% in ED patients presenting with abdominal pain. Up to 30% incidence in patients with abdominal pain and negative prior workup. More common in young women.
Diagnosis: Carnett’s test. Localize pain to specific area, then patient tenses abdominal wall by performing a sit-up or raising legs. Test is considered positive if pain increases or remains the same (78% sensitive, 88% specific).
Treatment: First-line is combination injection at site of entrapment with corticosteroid and local anesthesia under ultrasound guidance.
References:
- Suleiman, S, Johnston, D. “The Abdominal Wall: An Overlooked Source of Pain” American Family Physician. August 2001.
- Kanakarajan, S., et al. “Chronic Abdominal Wall Pain and Ultrasound-Guided Abdominal Cutaneous Nerve Infiltration: A Case Series.” Pain Medicine, volume 12, Issue 3, 1 March 2011, Pages 382-386.
- Mol FMU, Maatman RC, De Joode LEGH, Van Eerten P, Scheltinga MR, Roumen R. Characteristics of 1116 Consecutive Patients Diagnosed With Anterior Cutaneous Nerve Entrapment Syndrome (ACNES). Ann Surg. 2021 Feb 1;273(2):373-378. doi: 10.1097/SLA.0000000000003224. PMID: 30817351.
