A positive scratch collapse test in anterior cutaneous nerve entrapment syndrome indicates its neuropathic character.

OBJECTIVES: Chronic abdominal pain is occasionally caused by an abdominal wall entity such as anterior cutaneous nerve entrapment syndrome (ACNES). This syndrome is thought to occur due to intercostal nerve branches (T7-12) that are entrapped in the rectus abdominis muscles. The diagnosis is largely based on subjective clues in patient history and physical examination. A test referred to as the scratch collapse test (SCT) is used as an additional diagnostic tool in peripheral nerve entrapment syndromes such as the carpal tunnel syndrome. The aim of the present study is to investigate whether an SCT was positive in patients with suspected ACNES. If so, this finding may support its hypothesized neuropathic character. METHODS: A prospective, case-control study was performed among patients with ACNES (n = 20) and two control groups without ACNES (acute intra-abdominal pathology n = 20; healthy n = 20), all were consecutively included. ACNES was diagnosed based on previously published criteria. The SCT test was executed at the painful abdominal area in both patient groups and at a corresponding area in healthy controls. Predictive values, sensitivity, and specificity were calculated. Videos of tests were evaluated by blinded observers. RESULTS: SCT was judged positive in 19 of 20 ACNES patients but not in any of the 40 controls. A 95% sensitivity (confidence interval [CI]: 75-99) and optimal specificity (100%; CI: 83-100) were calculated. CONCLUSIONS: The positive SCT supports the hypothesis that ACNES is an entrapment neuropathy. A positive SCT should be considered a major diagnostic criterion for ACNES.

The Scratch Collapse Test in patients diagnosed with Anterior Cutaneous Nerve Entrapment Syndrome (ACNES): A report of three cases.

INTRODUCTION AND IMPORTANCE: The Scratch Collapse Test (SCT) is currently used as a supportive tool diagnosing peripheral nerve neuropathies including carpal tunnel syndrome or peroneal nerve entrapment. Some patients with chronic abdominal pain suffer from entrapment of terminal branches of intercostal nerves (anterior cutaneous nerve entrapment syndrome, ACNES). ACNES is characterized by a severe disabling pain at a predictable area of the anterior abdomen. Clinical examination shows altered skin sensation and painful pinching at the area of pain. However, these findings may be subjective. CASE PRESENTATION: In three female patients aged 71, 33, and 43 years with suspected ACNES, the SCT was positive when scratching over the skin of the affected nerve-ending at the abdominal wall. The diagnosis ACNES was confirmed with a local abdominal wall infiltration at the tenderpoint in all three patients. In case three, the SCT turned negative after lidocaine infiltration. CLINICAL DISCUSSION: ACNES was hitherto a clinical diagnosis just based on clues in medical history and physical examination. Performing a SCT in patients possibly having ACNES may additionally contribute to the diagnosis. CONCLUSION: The SCT may serve as an additional tool for diagnosing patients with possible ACNES. A positive SCT in patients with ACNES supports the hypothesis that ACNES is indeed a peripheral neuropathy of terminal branches of the lower thoracic intercostal nerves. Controlled research is necessary to confirm the role of a SCT in ACNES.