Genitofemoral Neuralgia

Excerpt

Genitofemoral neuralgia is a chronic, painful neuropathic condition caused by compression or trauma to the genitofemoral nerve and its branches. This condition usually presents with constant burning pain or discomfort in the inguinal region, along with hyperalgesia or anesthesia in the genitals and inner thighs. Genitofemoral neuralgia is a common cause of groin pain in both female and male patients, particularly after recent or previous surgical interventions that may have inadvertently damaged the genitofemoral nerve.

Magee first described this condition in 1942 as causalgia instead of neuralgia, as seen as a complication of appendicular surgery. Lyon renamed it genitofemoral neuralgia 3 years later, given its unique pain characteristics and cutaneous distribution. The genitofemoral nerve originates from the first 2 lumbar roots (L1 and L2). The nerve trunk then pierces the psoas muscle at the level of the third and fourth lumbar spine vertebrae, descending to the inguinal region along the anterior surface of the muscle. This trajectory makes it susceptible to injury from overly aggressive traction. The nerve passes under the ureter and bifurcates into the genital and femoral branches, which cross the inguinal ligament to enter the deep inguinal ring. Please see StatPearls' companion resource, "Anatomy, Abdomen and Pelvis: Genitofemoral Nerve," for more information.

The 2 branches usually follow separate and distinct anatomical courses after emerging on the surface of the psoas muscle.

1. In males, the genital branch travels along the spermatic cord through the inguinal canal to innervate the cremaster muscle and is responsible for the cremasteric reflex. Additionally, the genital nerve provides sensory innervation to the spermatic cord, lateral scrotum, and the adjacent ventromedial aspect of the thigh. The femoral branch provides purely sensory innervation to the skin of the upper anterior thigh.

1. In females, the genital branch travels alongside the round ligament to provide sensory innervation to the labia majora and mons pubis. The femoral branch of the nerve does not enter the inguinal canal; it travels under the inguinal ligament and externally to the femoral sheath.

The femoral branch is the most lateral structure within the femoral triangle, which also contains the femoral vessels and the lymph node of Cloquet. Please see StatPearls' companion resources, "Anatomy, Abdomen and Pelvis: Femoral Triangle," "Anatomy, Abdomen and Pelvis: Lymphatic Drainage," and "Anatomy, Abdomen and Pelvis: Inguinal Lymph Node," for more information. This nerve provides sensory innervation to the superior proximal anterior aspect of the thigh, lateral and anterior to the area covered by the ilioinguinal nerve. This nerve is susceptible to injury during procedures requiring femoral vein access, particularly if complicated by aneurysms, pseudoaneurysms, vessel perforations, or extensive dissection.

Additionally, oncological metastatic diseases such as sarcomas, femoral bone fractures, and orthopedic interventions can damage the nerve, causing sensory impairment. In some patients, the femoral branch of the genitofemoral nerve might have an overlapping sensory innervation with the lateral femoral nerve, which can further hinder and delay correct diagnosis.

The cremasteric reflex is produced through an afferent pathway innervated by the ilioinguinal nerve and the femoral branch of the genitofemoral nerve and an efferent pathway innervated by the genital branch of the genitofemoral nerve. The innervation of the afferent pathway has been contradictory, and no electrophysiological studies have been done to confirm results.

The anatomical distribution of the genitofemoral nerve, as in any other structure, is subjected to different anatomical variants. In 2001, Rab et al described the variability of the ilioinguinal and genitofemoral nerves. This anatomical variability has significant implications for surgical planning and interventions. Additionally, awareness of known variants improves accurate diagnosis and appropriate treatment of patients suffering from neuralgia.

Rab et al categorized the different anatomical variants of the ilioinguinal and genitofemoral nerves using the letters A through D. The most common anatomical distribution described in the literature follows Rab’s type C classification of the ilioinguinal and genitofemoral nerves (see Image. Anatomical Variations of Sensory Innervations).