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 involve 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 can occur spontaneously.
The ilioinguinal nerve (IIN) arises from the anterior ramus of L1 with some contributions from T12 and L2, similar to the iliohypogastric nerve (IHN), as part of the lumbar plexus. Emerging from the lateral border of the psoas major muscle, both nerves run subperitoneally in front of quadratus lumborum before piercing the transverse abdominis muscle above the iliac crest to become superficial. It pierces the internal oblique muscle mediocaudally to the anterior superior iliac spine (ASIS). The nerve enters the inguinal canal approximately 2 cm medial to the ASIS and exits through the superficial inguinal ring to function as a sensory nerve for the overlying skin. From there, it supplies innervation to the inner thigh and either scrotum or labia.