Anterior cutaneous nerve entrapment syndrome with pain present only during Carnett’s sign testing: a case report

BACKGROUND: The identification of anterior cutaneous nerve entrapment syndrome is often challenging, due to no widely accepted standard guidelines regarding laboratory and imaging tests for the diagnosis of ACNES. CASE PRESENTATION: A 77-year-old Japanese man presented with mild lower abdominal pain that had been present for the past 3 years. Physical examination revealed no abdominal pain during palpation, with normal laboratory and imaging testing; therefore, conservative therapy was initiated. However, the abdominal pain continued. Re-examination 16 days later revealed three tender points in accordance with intercostal nerves Th10, Th11, and Th12, with the pain occurring only during Carnett’s sign testing. A cutaneous injection of 1% lidocaine was administered, and the abdominal pain was resolved about 30 min later. Based on these results, anterior cutaneous nerve entrapment syndrome was diagnosed. CONCLUSIONS: It is sometimes hard to diagnose anterior cutaneous nerve entrapment syndrome without testing for Carnett’s sign. If patients present with chronic abdominal pain, clinicians should test for Carnett’s sign even if no pain is elicited during regular abdominal palpation.