Anterior cutaneous nerve entrapment syndrome (ACNES) causes chronic abdominal pain that may persist for months. It is predominantly found in children and is difficult to diagnose.
What is anterior cutaneous nerve entrapment syndrome ACNES?
Anterior cutaneous nerve entrapment syndrome (ACNES) occurs when nerve endings are ‘entrapped’ in abdominal muscles, producing a severe localised nerve (neuropathic) pain. It usually involves the lower thoracic intercostal nerves (7–12) at the front of the abdomen.
Difficulty diagnosing ACNES
When a patient first describes sharp abdominal pains, medical professionals will often be inclined to search the abdominal cavity for the root cause. Time will be spent conducting X-rays, ultrasounds, MRIs, intestinal transit tests, as well as blood and stool tests.
Thus, it may take a while before they turn to exploring the abdominal wall, where the source of the problem lies. It is precisely its location (in the abdominal wall) that makes ACNES difficult to diagnose.
This difficulty is made worse when the patient is a young child unable to communicate well. Adults, being able to communicate accurately, often refer to this distinct neuropathic pain “as if they have a hole” in a small area of abdominal skin.
Recent cases of ACNES at Hospital Ochoa
Dr Paulino Uclés Moreno, specialist in Clinical Neurophysiology at Hospital Ochoa, recently received a distressed 11-year-old boy with such symptoms. The paediatrician involved suspected it could be nerve entrapment, but the diagnosis of ACNES lacks strong clinical evidence.
Typically, only Carnett’s sign (a test whereby a clinician palpates the source of the pain while the patient contracts their abdomen) or temporary pain relief after local anaesthesia, are used to diagnose ACNES. However, Dr Uclés Moreno decided to conduct a somatosensory evoked potentials (SEP) test as is applied to nerve compressions in the extremities or spinal column. The result was positive.
Details of this case were published in a scientific medical journal. Shortly afterwards, an adult patient received the same SEP test, which also turned out positive, thereby confirming the source of their long-standing pain.
In both instances, the application of local anaesthesia and a corticosteroid eliminated the pain.