Chronic Abdominal Pain

  What is Chronic Abdominal Wall Pain (ACNES)?

• Chronic abdominal wall pain is pain that originates from the muscles, fascia, or nerves of the abdominal wall rather than from the organs inside the abdomen. It is an under-recognised condition and is often mistaken for pain arising from the stomach, bowel, or other abdominal organs.
• One of the most common causes is Anterior Cutaneous Nerve Entrapment Syndrome (ACNES). This occurs when one of the small sensory nerves supplying the abdominal wall becomes trapped as it passes through the abdominal muscles, resulting in persistent pain.
• Abdominal wall pain may also develop following surgery, injury, infection (including shingles), pregnancy, repetitive strain, or without any obvious trigger. In some people, ongoing pain may be accompanied by changes within the nervous system (central sensitisation), making the pain more widespread or persistent.
• Diagnosis is primarily based on a detailed history and clinical examination. Blood tests, ultrasound scans, CT scans, and MRI scans are often normal because they assess the internal organs rather than the abdominal wall itself.

  What are the Symptoms?

     Common symptoms include:

• A well-localised area of pain that can often be covered with one or two fingertips.
• Sharp, aching, burning, or stabbing pain.
• Pain that worsens with coughing, sneezing, laughing, twisting, reaching, or sitting up.
• Increased pain when tightening the abdominal muscles, such as during a sit-up or when getting out of bed.
• Tenderness over a specific point in the abdominal wall.
• Altered skin sensation, including numbness, tingling, or increased sensitivity around the painful area.
• Pain that may be present constantly or occur in episodes.

  What are the Treatment Options?

• Treatment depends on the underlying cause, the duration of symptoms, and the impact on your daily life. Most patients benefit from a combination of treatments.

  Education and Reassurance

• Understanding that the pain originates from the abdominal wall rather than the internal organs can be reassuring, particularly after extensive investigations have excluded serious disease.

  Physiotherapy

• Where muscle weakness, scar tissue, or altered movement patterns contribute to pain, physiotherapy may help by improving strength, flexibility, posture, and movement.

  Medications

• Pain-modulating medications such as duloxetine or amitriptyline may be considered when nerve sensitivity or central sensitisation is contributing to symptoms.
• Long-term opioid therapy is generally not recommended for chronic abdominal wall pain because evidence of long-term benefit is limited and the risks increase over time.

  Procedures

• Ultrasound-Guided Abdominal Wall Nerve Blocks

For patients with suspected ACNES or other abdominal wall nerve pain, an ultrasound-guided abdominal wall nerve block may be recommended.

This involves injecting local anaesthetic, sometimes combined with corticosteroid, around the affected nerve. The injection can serve both as a diagnostic test and as a treatment. Some patients experience prolonged relief, while others may require further treatment.

• Trigger Point Injections

If pain arises from muscle trigger points within the abdominal wall, trigger point injections may help reduce muscle spasm and improve function.

• Pulsed Radiofrequency

In carefully selected patients whose pain responds well to diagnostic nerve blocks but later returns, pulsed radiofrequency treatment may be considered to reduce nerve sensitivity without permanently damaging the nerve.