ACNES in Children: Fibrotic Entrapment & Traumatic Neuroma Mechanisms

A recent case study published in Cureus details the complex presentation of abdominal pain in a child following laparoscopic percutaneous extraperitoneal closure (LPEC), revealing the coexistence of non-inflammatory fibrotic entrapment and a traumatic neuroma as distinct mechanisms contributing to anterior cutaneous nerve entrapment syndrome (ACNES). The findings highlight the challenges in diagnosing abdominal wall neuropathic pain and the potential for multiple underlying causes even in a single patient.

The case, reported on May 1, 2026, involved a child who developed pain at two separate sites after undergoing LPEC. Initial examination suggested ACNES, a condition where nerve endings of the lower thoracic intercostal nerves become entrapped in abdominal muscles, causing localized neuropathic pain. However, further investigation revealed a more nuanced picture.

Distinct Mechanisms Identified

Researchers identified two separate mechanisms contributing to the child’s pain. The first was non-inflammatory fibrotic entrapment, where nerve fibers were compressed by scar tissue. The second was a traumatic neuroma, a disorganized mass of nerve tissue that forms after nerve injury. The study emphasizes that these two mechanisms can occur simultaneously, complicating diagnosis and treatment.

According to the published case study, the pain experienced at both sites resolved without recurrence following postoperative care. This suggests that identifying and addressing the specific underlying mechanism—whether fibrotic entrapment or traumatic neuroma—is crucial for effective pain management.

Understanding ACNES

Anterior cutaneous nerve entrapment syndrome (ACNES) is a nerve entrapment condition causing chronic abdominal pain. It occurs when the anterior branch of the abdominal cutaneous nerve is compressed as it passes through the anterior rectus abdominis muscle fascia. The condition is often overlooked, leading to diagnostic delays and misdiagnoses, with an estimated incidence of approximately 1 in 2,000 patients.

Symptoms of ACNES can mimic other conditions, such as irritable bowel syndrome or appendicitis, further contributing to misdiagnosis. Affected individuals often experience limited relief from standard pain medication, although some neuroleptic agents may provide some benefit. Patients may also report ‘pseudovisceral’ phenomena, including nausea, bloating, and altered bowel habits.

Pain associated with ACNES is typically exacerbated by tensing the abdominal wall muscles, making movement painful. Lying quietly often provides the most relief.

Challenges in Diagnosis and the Importance of Differentiation

The case study underscores the importance of considering multiple potential causes of abdominal wall pain, particularly following surgical procedures like LPEC. The coexistence of fibrotic entrapment and traumatic neuroma highlights the need for a thorough diagnostic evaluation to accurately identify the underlying mechanisms driving the pain.

The relative unfamiliarity with ACNES among physicians contributes to diagnostic delays. Accurate diagnosis is critical to avoid unnecessary diagnostic interventions and ineffective treatments. The study suggests that a detailed understanding of the different mechanisms involved in abdominal wall neuropathic pain is essential for providing appropriate and targeted care.

While this case focuses on a pediatric patient, ACNES can occur in adults as well. Further research is needed to better understand the prevalence, risk factors, and optimal treatment strategies for this often-misunderstood condition.