Unilateral swelling of the lower abdominal wall. Unusual clinical manifestation of an upper lumbar disc herniation.

Circumscribed unilateral paralysis of abdominal muscles is a rare clinical feature and has previously been described in diabetic neuropathies and traumatic or non-traumatic compressive neuropathies. The paper describes a case presenting with transversus abdominis muscle paralysis and burning paraesthesia in the anterolateral aspect of the thigh caused by a lateral L2-L3 disc herniation. Abdominal echography and the EMG investigation led to the suspicion of a disc prolapse which was eventually verified by myelography completed with a CT scan. Surgery confirmed L2 root compression by a large calcified herniation in the intervertebral foramen L2-L3. The anatomical principles are recalled to explain the clinical manifestations.