The Clinical Syndrome

Genitofemoral neuralgia is one of the most common causes of lower abdominal and pelvic pain encountered in clinical practice. It may be caused by compression of or damage to the genitofemoral nerve anywhere along its path. The most common causes of genitofemoral neuralgia involve traumatic injury to the nerve, including direct blunt trauma and damage during inguinal herniorrhaphy and pelvic surgery. Rarely, genitofemoral neuralgia occurs spontaneously.

The genitofemoral nerve arises from fibers of the L1 and L2 nerve roots and passes through the substance of the psoas muscle, where it divides into a genital and a femoral branch. The femoral branch passes beneath the inguinal ligament, along with the femoral artery, and provides sensory innervation to a small area of skin on the inner thigh. The genital branch passes through the inguinal canal to provide innervation to the round ligament of the uterus and labia majora in women. In men, the genital branch passes with the spermatic cord to innervate the cremasteric muscles and provide sensory innervation to the bottom of the scrotum.

Signs and Symptoms

Genitofemoral neuralgia manifests as paresthesias, burning pain, and occasionally numbness over the lower abdomen that radiates to the inner thigh in both men and women and into the labia majora in women and the bottom of the scrotum and cremasteric muscles in men ( Fig. 81.1 ); the pain does not radiate below the knee. The pain of genitofemoral neuralgia worsens with extension of the lumbar spine, which puts traction on the nerve. Therefore patients with genitofemoral neuralgia often assume a bent-forward, novice skier’s position (see Fig. 81.1 ).

The pain of genitofemoral neuralgia radiates into the inner thigh of men and women and into the labia majora in women and the inferior scrotum in men.

Physical findings include sensory deficit in the inner thigh, base of the scrotum, or labia majora in the distribution of the genitofemoral nerve. Weakness of the anterior abdominal wall musculature may be present. Tinel sign may be elicited by tapping over the genitofemoral nerve at the point where it passes beneath the inguinal ligament.

Testing

Electromyography (EMG) can distinguish genitofemoral nerve entrapment from lumbar plexopathy, lumbar radiculopathy, and diabetic polyneuropathy. Plain radiographs of the hip and pelvis are indicated in all patients who present with genitofemoral neuralgia, to rule out occult bony disease. Based on the patient’s clinical presentation, additional testing may be warranted, including a complete blood count, uric acid level, erythrocyte sedimentation rate, and antinuclear antibody testing. Magnetic resonance imaging (MRI) of the lumbar plexus is indicated if tumor or hematoma is suspected. The injection technique described later serves as both a diagnostic and a therapeutic maneuver.