It has been estimated that some 30% of all chronic abdominal pain (defined as 3 months or more) that presents repeatedly to a GP or the Emergency Department is caused by non-surgical (non-internal) conditions. One of the most common conditions is Abdominal Cutaneous Nerve Entrapment Syndrome (ACNES).
The nerves that supply the skin of the abdomen travel through some very tight tunnels in the rectus abdominis (six pack) muscle where it can be subject to entrapment (or pinching). This can be compared to nerve entrapments in other parts of the body such Carpal Tunnel Syndrome or Sciatica.
Pain can be of any nature but typically presents as burning, boring, sharp and sometimes even present as intermittent severe attacks. It is usually worse with certain positions or postures and there can be one or more exquisitely tender point(s) along the edge(s) of the rectus abdominal muscle(s). As one can imagine, the presentation is non-specific and can mimic serious surgical conditions. These patients have often been subjected to exhaustive tests such as imaging, endoscopy or multiple surgical operations with no cause found. It is unclear what the best treatment for this condition is as oral pain medications seem to be of limited use.
Our practise has developed a special Ultrasound facilitated technique to target the offending nerve with a steroid injection. A patient can be given up to 3 steroid injections over a 6 month period. The success rate is up to 95%.
Uncertain outcomes can be expected in the following patients:
- The abdominal pain is part of a systemic chronic pain syndrome. This could be prolonged chronic pain or connective tissue diseases known to be associated with multiple joint and soft tissue pain.
- Chronic mechanical thoracic spine pain causing tension of the source cutaneous nerve. The abdominal pain is unlikely to settle without also addressing the back pain first.
- Multiple discrete points of pain (multiple entrapped cutaneous nerves)
- Multiple points of abdominal wall pain which may be due to trigger points or fibromyalgia rather than true cutaneous nerve entrapment.
Recalcitrant cases will be worked up by our Pain Physician colleagues for other more invasive interventions such as pulsed Radio-Frequency Ablation (pRFA). Surgery to decompress the nerve may rarely be required in difficult cases.