Abdominal Cutaneous Nerve Entrapment Syndrome (ACNES): A Commonly Overlooked Cause of Abdominal Pain

Abstract

Abdominal cutaneous nerve entrapment syndrome (ACNES) may sound like an esoteric condition rarely seen by clinicians but is a common condition. When a patient is seen for abdominal pain without other clinically significant symptoms, ACNES should be high on the list of likely diagnoses. Beginning in 1792 with J P Frank’s description of the condition he named “peritonitis muscularis,”1 a sampling of pertinent medical literature on this subject2–9 shows how often the subject has been written about over the years. These articles state that abdominal wall pain is often wrongly attributed to intra-abdominal disorders and that this misdirected diagnosis can lead to unnecessary consultation, testing, and even abdominal surgery, all of which can be avoided if the initial examiner makes the right diagnosis. In a study of 117 patients in 1999, Greenbaum10 estimated that the amount of money expended on unnecessary workup was $914 per patient. In 2001, Thompson et al11 noted that an average of $6727 per patient was required for previous diagnostic testing and hospital charges. Hershfield6 listed preliminary diagnoses of patients referred to him as irritable bowel, spastic colon, gastritis, psychoneurosis, depression, anxiety, hysteria, and malingering. Many of these patients were given a psychiatric diagnosis when the actual diagnosis could not be determined. In fact, the most common cause of abdominal wall pain is nerve entrapment at the lateral border of the rectus abdominis muscle;3,5,8,9,12 Carnett,3 in the early 20th century, called this syndrome “intercostal neuralgia” and claimed to have seen three patients per week with this diagnosis and as many as three per day in consultation sessions. In my own primary care practice, I have seen one or two patients with this diagnosis for every 150 patients overall but have seen as many as three such patients per consultation session in a busy evening clinic where 15 or more clinicians were on duty. Acute cases of ACNES are usually seen in the evening, especially in spring and summer, when people are more active. Chronic and recurrent cases are more likely to be seen in the daytime throughout the year. To avoid causing the patient unnecessary anxiety and tension, loss of work time, and both the expense and possible hazard of multiple diagnostic procedures, the first physician examining the patient must establish the diagnosis of ACNES if this condition is present. Compiled from my own experience and that of other investigators who have written about ACNES, the information presented here should give readers the tools necessary for diagnosing and treating this condition.