Genitofemoral neuralgia is a cause of neuropathic pain that is often debilitating in nature. It is characterized by chronic neuropathic groin pain that is localized along the distribution of the genitofemoral nerve. Genitofemoral neuropathy has been attributed to iatrogenic nerve injury occurring during inguinal and femoral herniorrhaphy, with cases developing after both open and laparoscopic techniques. Diagnosis of genitofemoral neuralgia can be challenging, due to the overlap in sensory distribution the nerve shares with the ilioinguinal and iliohypogastric nerve. Differential nerve blocks are recommended in an effort to differentiate the nerves when patients present with lower abdominal and groin pain. Once a diagnosis has been made, there exist several treatment options for genitofemoral neuralgia ranging from medical management, non-invasive injections, and surgery. Literature has also brought light to pulsed radiofrequency ablation and cryoablation performed under ultrasound guidance as emerging treatments.
Etiology and Pathogenesis
Genitofemoral neuralgia was first described in 1942 by Magee, who coined the term genitofemoral “causalgia.” The majority of patients described by Magee presented with pain along the distribution of the GFN after undergoing appendicular surgery. Injury to the genitofemoral nerve is almost always secondary to direct trauma. Direct trauma is almost always the result of surgery. Complications following inguinal herniorrhaphy and laparoscopic varicocelectomy are cited relatively frequently and can stem from inflammation, neuroma formation, deafferentation, or entrapment. Entrapment neuropathy can occur from impingement from staples or tacks which are used to affix the prosthetic mesh, the mesh itself, direct injury, or myofascial scarring.
Additionally, it is not uncommon for genitofemoral neuralgia to be induced during the performance of a lumbar sympathetic block. Lumbar sympathetic blocks, which are traditionally performed by injecting a needle from a posterior position toward the anterolateral aspect of the vertebral body, may allow for the injected solution to leak back along the needle shaft and spread toward the genitofemoral nerve, acting as a noxious irritant on the nerve.
Other factors, such as an abscess or mass dwelling within or near the psoas major muscle, complications secondary to appendectomy, inguinal lymph node dissection, orchiectomy, total abdominal hysterectomy, abdominoplasty, iliac crest bone graft, femoral catheter placement, cesarean section, thermal damage following radiofrequency ablation of renal cell carcinoma, direct injury from an inguinal herniated mass and complications from leprosy have also been noted.
Aside from iatrogenic causes, review of the literature has revealed some instances of idiopathic genitofemoral neuropathy. O’Brien (1979) reported a patient with what appeared to be idiopathic genitofemoral neuralgia. Occupational history of the patient revealed they modeled extremely tight jeans. Bicycle riding has also been reported as another possible association with spontaneous genitofemoral neuralgia.