THE CLINICAL SYNDROME
Ilioinguinal neuralgia is one of the most common causes of lower abdominal and pelvic pain encountered in clinical practice. Ilioinguinal neuralgia is caused by compression of the ilioinguinal nerve as it passes through the transverse abdominis muscle at the level of the anterior superior iliac spine. The most common causes of compression of the ilioinguinal nerve at this anatomic location involved injury to the nerve induced by trauma, including direct blunt trauma to the nerve, as well as damage during inguinal herniorrhaphy and pelvic surgery. Rarely, ilioinguinal neuralgia will occur spontaneously.
SIGNS AND SYMPTOMS
Ilioinguinal neuralgia presents as paresthesias, burning pain, and occasionally numbness over the lower abdomen that radiates into the scrotum or labia and occasionally into the inner upper thigh. The pain does not radiate below the knee. The pain of ilioinguinal neuralgia is made worse by extension of the lumbar spine, which puts traction on the nerve. Patients suffering from ilioinguinal neuralgia will often assume a bent-forward novice skier’s position. If the condition remains untreated, progressive motor deficit consisting of bulging of the anterior abdominal wall muscles may occur. This bulging may be confused with inguinal hernia.
The patient suffering from ilioinguinal neuralgia will often bend forward in the novice skier's position to relieve the pain.
Physical findings include sensory deficit in the inner thigh, scrotum, or labia in the distribution of the ilioinguinal nerve. Weakness of the anterior abdominal wall musculature may be present. Tinel’s sign may be elicited by tapping over the ilioinguinal nerve at the point at which it pierces the transverse abdominal muscle. As mentioned, the patient may assume a bent-forward novice skier’s position.
Pharmacologic management of ilioinguinal neuralgia is usually disappointing, and general nerve block will be required to provide pain relief. Initial treatment of ilioinguinal neuralgia should consist of treatment of ilioinguinal neuralgia should consist of treatment with simple analgesics, nonsteroidal anti-inflammatory drugs, or cyclooxygenase-2 inhibitors. Avoidance of repetitive activities thought to exacerbate the symptoms of ilioinguinal neuralgia (e.g., squatting or sitting for prolong periods) will also help ameliorate the patient’s symptoms. If the patient fails to respond to these conservative measures, a next reasonable step is ilioinguinal nerve block with local anesthetic and steroid.
Ilioinguinal nerve block is performed by placing the patient in the supine position with a pillow under the knees, if lying with the legs extended increases the patient’s pain due to traction on the nerve.
Because of overlapping innervation of the ilioinguinal and iliohypogastric nerve, it is not unusual to block branches of each nerve when performing ilioinguinal nerve block. The clinician should be aware that due to the anatomy of the ilioinguinal nerve, damage to or entrapment of the nerve anywhere along its course can produce a similar clinical syndrome.
Correct needle placement for ilioinguinal nerve block.
For patients who do not rapidly respond to ilioinguinal nerve block, consideration should be given to epidural steroid injection of the T12-L1 segments. If a patient presents with pain suggestive of ilioinguinal nerve blocks, a diagnosis of lesions more proximal in the lumbar plexus or an L1 radiculopathy should be considered. Such patients will often respond to epidural steroid blocks.