Description:
Anterior cutaneous nerve entrapment syndrome is described as actually one of the most common chronic abdominal wall pain conditions and is often underdiagnosed.
Pathophysiology:
The cutaneous branches of sensory nerves from T7-T12 travel through channels in the abdominal wall fascia at the linea semilunaris and do a 90 degree turn to innervate the cutaneous surface of the abdomen
Usually this neurovascular bundle is protected by fat however in times of trauma, surgery, or idiopathic causes, the nerve can be entrapped causing significant discomfort across the abdominal wall
Risk factors:
Tight clothing
Belts
Increased abdominal pressure
Scarring
Obesity
Previous surgery
Women 4:1 Men
History features:
Patients often describe a fairly localised pain with tenderness within a small area of the abdominal wall
The pain is typically at the lateral edge of the rectus abdominis muscles and is more common on the R than the left (though the pain can be felt anywhere over the abdomen due to referral)
The pain is typically sharp in nature and worse with different postures and positions
Physical examination:
Palpation - Typical pressure with a Q-tip can show an area of max tenderness
Carnett's sign - Patient lifts their head and shoulders while you apply pressure over the area of pain on the abdomen. Tightening of the abdominal muscles can protect internal organs from palpation pressure whereas abdominal wall pathology will remain as tender as before, or worse.
Management:
Trigger point injections can be both a treatment and confirm diagnosis
It provides relief in 80-90% of patients
Injections can be repeated as required
Hydrodissection and steroidal thinning of connective tissue is thought to help
Chemical neurolysis and/or surgical neurolysis can be considered
Need to avoid stomach crunches and pressure on the area
Reference:
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