Iliohypogastric Nerve Block

Indications and Clinical Considerations

Iliohypogastric nerve block is useful in evaluating and managing groin pain thought to be subserved by the iliohypogastric nerve, including the pain associated with iliohypogastric neuralgia. The technique also is useful for providing surgical anesthesia for groin surgery, including inguinal herniorrhaphy when combined with ilioinguinal and genitofemoral nerve block. Iliohypogastric nerve block with local anesthetic can be used diagnostically during differential neural blockade on an anatomic basis in the evaluation of groin pain when peripheral nerve entrapment versus lumbar radiculopathy is being evaluated. If destruction of the iliohypogastric nerve is being considered, this technique is useful as a prognostic indicator of the degree of motor and sensory impairment. Iliohypogastric nerve block with local anesthetic may be used to palliate acute pain emergencies, including postoperative pain relief, while waiting for pharmacologic methods to become effective. Iliohypogastric nerve block with local anesthetic and steroids also is useful in the treatment of persistent pain after inguinal surgery or groin trauma when the pain is thought to be secondary to inflammation or entrapment of the iliohypogastric nerve.

Destruction of the iliohypogastric nerve is occasionally indicated for the palliation of persistent groin pain after blunt or open trauma to the groin or persistent pain mediated by the iliohypogastric nerve after groin or lower abdominal surgery. Iliohypogastric nerve block via a 25-gauge needle may be performed in the presence of coagulopathy or anticoagulation, albeit with an increased risk for ecchymosis and hematoma formation.

Clinically Relevant Anatomy

The iliohypogastric nerve is a branch of the L1 nerve root with a contribution from T12 in some patients ( Fig. 141.1 ). The nerve follows a curvilinear course that takes it from its origin of the L1 and occasionally T12 somatic nerves to inside the concavity of the ilium ( Fig. 141.2 ). The iliohypogastric nerve continues anteriorly to perforate the transverse abdominis muscle to lie between it and the external oblique muscle ( Fig. 141.3 ). At this point, the iliohypogastric nerve divides into an anterior and a lateral branch. The lateral branch provides cutaneous sensory innervation to the posterolateral gluteal region. The anterior branch pierces the external oblique muscle just beyond the anterior superior iliac spine to provide cutaneous sensory innervation to the abdominal skin above the pubis (see Fig. 141.3 ). The nerve may interconnect with the ilioinguinal nerve along its course, resulting in variation of the distribution of the sensory innervation of the iliohypogastric and ilioinguinal nerves.