Ilioinguinal Neuralgia: An Introduction

Ilioinguinal neuralgia most commonly presents as persistent pain after inguinal hernia surgery.

Ilioinguinal neuralgia is an increasingly common disorder characterized by pain in the lower abdominal wall just above the crease of the hip. The pain may be highly localized or may seem to travel along the course of the nerve along a line connecting the iliac crest and the symphysis pubis. It is usually unilateral and most often follows a history of trauma to the region.


The source of trauma is most often surgical, but pain after a direct blow or a seatbelt injury occurs more commonly than previously appreciated. The pain most often follows an inguinal herniorrhaphy or a pelvic procedure done through a low Pfannenstiel incision. Surgeons have long known that as many as 20% of patients will have pain for up to one year and in rare cases longer after an uncomplicated hernia repair. Re-exploration of painful incisions almost never demonstrates neuroma formation or any other surgically correctable cause of pain. Newer imaging modalities, most commonly MRI demonstrate some scarring around the nerve, but the degree of scarring is usually not significantly greater than after non-painful hernia repairs.


The diagnosis of ilioinguinal neuralgia is usually established by blockade of the nerve, wherein a small amount of local anesthetic is injected around the nerve. Most practitioners will also add a modest dose of corticosteroid medication in the hope that the block will not only be diagnostic but therapeutic as well. The usefulness of this approach has recently been increased with the widespread use of ultrasonic guidance for localization of the nerve. Ultrasound is much more accurate than either anatomical placement based on surface landmarks or fluoroscopy. This increased accuracy allows for smaller injectate volumes and therefore much greater diagnostic specificity. Occasionally the patient fails to experience pain relief even though the area served by the ilioinguinal nerve is completely numb. This is usually considered an unfavorable sign. If the ilioinguinal nerve block is temporarily effective it can be repeated.


In cases where repeated ilioinguinal nerve blocks are temporarily effective but fail to produce lasting relief, a long lasting therapy to disable the nerve such as cryoablation or radiofrequency ablation can be used. Unfortunately, this type of therapy tends to be transient in nature. For some reason patients often return 2 to 3 months after the ablation with a return of their pain. In most of these cases the area served by the ilioinguinal is still numb. This phenomenon along with those case where ilioinguinal nerve blocks is ineffective in even temporarily relieving pain underscore the fact that in all likelihood this is a functional disorder of nerve regulation, similar to CRPS or phantom limb pain.


When nerve blocks and other ablative therapies fail many of these patients can be salvaged using neurostimulation. Since the ilioinguinal nerve is relatively superficial, stimulation can often be achieved from outside of the body with a TENS unit, especially in thinner individuals. When TENS therapy fails either for anatomical reasons or because the patient cannot use the device of a sufficient portion of the day, a trial of spinal cord and peripheral nerve stimulation is in order. When the trial is successful long-term results are often excellent.


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