Both the iliohypogastric (IH) and ilioinguinal (II) nerves arise from the first lumbar nerve (L1) on each side of the body. The ilioinguinal nerve is a smaller nerve and courses below the iliohypogastric nerve. Both nerves run together as a pair, and from their point of origin in the spine, they travel through the abdominal wall muscles along the lower part of the abdomen where it joins with the pelvis. The iliohypogastric nerve on each side supplies sensation to the skin over the lower abdomen where it joins with the upper pelvis. The ilioinguinal nerve on each side provides sensation to the upper pelvis and along the middle portion of the thigh.
The nerves, because of where they are located, are at risk of being injured during lower abdominal surgery. These surgeries may include Pfannenstiel incision for a c-section, appendectomy, inguinal herniorrhaphy, or laparoscopic surgery, which commonly requires a trocar insertion.
As a result, patients may suffer from chronic post-surgical pain due to nerve injury. Patients suffering from post-surgical neuropathy have groin pain that may extend to the scrotum or the testicle in men, the labia majora in women, and the medial aspect of the thigh.
Ilioinguinal and iliohypogastric nerve blocks are a minimally invasive, non-surgical treatment for chronic pain. These nerve blocks can help in the diagnosis of chronic hip, groin, and pelvic pain. In addition, this pain management technique can also provide therapeutic relief by reducing pain signals originating from these nerves.
An iliohypogastric/Ilioinguinal nerve block is typically performed at the same time. They travel in very close proximity, and there is significant overlap in the sensation distribution these nerves provide. The nerve block is performed either with the assistance of landmarks that can be easily felt by touch, or under imaging guidance (a live x-ray or ultrasound machine) to increase the accuracy of this procedure.
This procedure is safe. However, with any procedure, there are risks, side effects and possibility of complications. The most common side effect is temporary pain at the injection site. Other less common risks include bleeding, infection, or injection into blood vessels and surrounding organs. Fortunately, serious side effects and complications are uncommon. X-ray guidance or ultrasound to provide visualization of the targeted structures significantly minimizes risk.