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Genitofemoral Nerve
Genitofemoral Nerve MM Roberts, Rehabilitation Institute of Chicago, Chicago, IL, USA r 2014 Elsevier Inc. All rights reserved. This article is a revision of the previous edition article by Richard K Olney, volume 2, p 442, r 2003, Elsevier Inc.
The genitofemoral nerve is a small, mixed sensory, and motor nerve derived from the first and second lumbar spinal nerves as part of the lumbar plexus. After forming within the posterior psoas muscle, it descends obliquely to emerge on the anterior surface of the muscle at the L3 or L4 vertebral level. As it continues inferiorly, it crosses behind the ureter and divides into two branches just proximal to the inguinal ligament. The genital branch passes through the deep inguinal ring and runs in the inguinal canal, with the spermatic cord, to innervate the cremaster muscle and supply the skin of the scrotum and adjacent thigh in the male, and with the round ligament to provide cutaneous sensation to the mons pubis and labium majus and adjacent thigh in the female. The femoral branch passes under the inguinal ligament and enters the femoral sheath lateral to the femoral artery, exiting anteriorly to supply the skin over the proximal thigh in the region of the femoral triangle. There is frequent variability in the branches and their distribution. In addition, anatomical variations are common with communicating fibers routinely identified to the ilioinguinal, as well as the iliohypogastric, and even lateral femoral cutaneous nerve. The genitofemoral nerve has an essential role in the inguinoscrotal phase of testicular descent in the male fetus. Although genitofemoral neuropathy is most commonly associated with operative injury or subsequent scarring with entrapment and/or neuroma formation after lower abdominal procedures (such as inquinal herniorrhaphy, appendectomy, or gynecological procedures such as hysterectomy or cesarean section) the nerve trunk or its branches may be injured anywhere along its course. At the origin, in the psoas muscle, it may be affected as part of a retroperitoneal compartment syndrome (due to abscess or hemorrhage) or in a more focal manner during a direct lateral transpsoas approach to the lumbar spine or during lumbar sympathetic blocks or neurolysis. It may be subject to thermal injury during radiofrequency ablation of renal cell carcinoma on the medial aspect of the kidney. It has been entrapped with the ureteric stump during stapling after nephrectomy. Use of a transverse lower abdominal incision may injure the nerve, especially if extended laterally. There is also evidence that a large hernia sac may compress the nerve as it passes into the inguinal canal. More distally, it has been injured during varicocele ligation and orchiectomy. Symptoms may develop acutely, but onset may be delayed months to years. Patients present with pain and paresthesias in the groin, upper inner thigh, and/or the scrotum or labium and findings of tenderness to palpation, occasionally a Tinel’s sign, hypoesthia or hyperesthesia of the skin, and loss of the cremasteric reflex, in males. Hyperextension and rotation of the spine away from the symptomatic side may exacerbate
420
symptoms but is nonspecific and flexion may also be provocative. Hip extension or rotation, either internal or external, may also elicit pain, and activities such as walking may worsen the symptoms. The differential should include upper lumbar radiculopathy, lesions of the ilioinguinal and iliohypogastric nerves, and local causes of groin pain. Precise diagnosis may be confounded by anatomical variability and overlap of nerve distribution. Electrodiagnostic testing of the genitofemoral nerve has been described but sensory conduction studies are technically challenging and have not proven reliable. A motor conduction study has been described but is not generally available for clinical use and has no utility in females. Selective nerve blocks may be diagnostic as well as therapeutic. Injection of the ilioinguinal and iliohypogastric nerves will not impact symptoms due to genitofemoral neuropathy, whereas L1 and L2 root blocks should provide relief. A transpsoas genitofemoral nerve block has also been described. Treatment options include avoidance of aggravating positions and activity, local measures such as ice, topical anesthetics, or capsaicin cream, and soft tissue techniques for scar release. Biofeedback and transcutaneous electrical stimulation may also be useful. Oral medications include anticonvulsants, tricyclic antidepressants, and nonsteroidal antiinflammatory medications, as well as narcotics. When conservative measures are inadequate, nerve ablation or surgical excision may be indicated. Before selecting an approach, consideration must be given to potential involvement of the nerve in the retroperitoneal space or the preperitoneal segment of the genital branch, as interruption distal to that site will not provide relief.
See also: Femoral Nerves
Further reading Amid PK (2011) Surgical treatment of chronic groin and testicular pain after laparoscopic and open preperitoneal inguinal hernia repair. Journal American College Surgeons 213: 531–536. Ducic I, Moxley M, and Al-Attar A (2006) Algorithm for treatment of postoperative incisional groin pain after cesarean delivery or hysterectomy. Obstetrics & Gynecology 108: 27–31. Parris D, Fischbein N, Mackey S, and Carroll I (2010) A novel CT-guided transpsoas approach to diagnostic genitofemoral nerve block and ablation. Pain Medicine 11: 785–789. Rab M, Ebmer J, and Dellon AL (2001) Anatomic variability of the ilioinguinal and genitofemoral nerve: Implications for the treatment of groin pain. Plastic and Reconstructive Surgery 108: 1618–1623.
Encyclopedia of the Neurological Sciences, Volume 2
doi:10.1016/B978-0-12-385157-4.00661-8
The genitofemoral nerve is a small, mixed sensory, and motor nerve derived from the first and second lumbar spinal nerves as part of the lumbar plexus. After forming within the posterior psoas muscle, it descends obliquely to emerge on the anterior surface of the muscle at the L3 or L4 vertebral level. As it continues inferiorly, it crosses behind the ureter and divides into two branches just proximal to the inguinal ligament. The genital branch passes through the deep inguinal ring and runs in the inguinal canal, with the spermatic cord, to innervate the cremaster muscle and supply the skin of the scrotum and adjacent thigh in the male, and with the round ligament to provide cutaneous sensation to the mons pubis and labium majus and adjacent thigh in the female. The femoral branch passes under the inguinal ligament and enters the femoral sheath lateral to the femoral artery, exiting anteriorly to supply the skin over the proximal thigh in the region of the femoral triangle. There is frequent variability in the branches and their distribution. In addition, anatomical variations are common with communicating fibers routinely identified to the ilioinguinal, as well as the iliohypogastric, and even lateral femoral cutaneous nerve. The genitofemoral nerve has an essential role in the inguinoscrotal phase of testicular descent in the male fetus. Although genitofemoral neuropathy is most commonly associated with operative injury or subsequent scarring with entrapment and/or neuroma formation after lower abdominal procedures (such as inquinal herniorrhaphy, appendectomy, or gynecological procedures such as hysterectomy or cesarean section) the nerve trunk or its branches may be injured anywhere along its course. At the origin, in the psoas muscle, it may be affected as part of a retroperitoneal compartment syndrome (due to abscess or hemorrhage) or in a more focal manner during a direct lateral transpsoas approach to the lumbar spine or during lumbar sympathetic blocks or neurolysis. It may be subject to thermal injury during radiofrequency ablation of renal cell carcinoma on the medial aspect of the kidney. It has been entrapped with the ureteric stump during stapling after nephrectomy. Use of a transverse lower abdominal incision may injure the nerve, especially if extended laterally. There is also evidence that a large hernia sac may compress the nerve as it passes into the inguinal canal. More distally, it has been injured during varicocele ligation and orchiectomy. Symptoms may develop acutely, but onset may be delayed months to years. Patients present with pain and paresthesias in the groin, upper inner thigh, and/or the scrotum or labium and findings of tenderness to palpation, occasionally a Tinel’s sign, hypoesthia or hyperesthesia of the skin, and loss of the cremasteric reflex, in males. Hyperextension and rotation of the spine away from the symptomatic side may exacerbate
420
symptoms but is nonspecific and flexion may also be provocative. Hip extension or rotation, either internal or external, may also elicit pain, and activities such as walking may worsen the symptoms. The differential should include upper lumbar radiculopathy, lesions of the ilioinguinal and iliohypogastric nerves, and local causes of groin pain. Precise diagnosis may be confounded by anatomical variability and overlap of nerve distribution. Electrodiagnostic testing of the genitofemoral nerve has been described but sensory conduction studies are technically challenging and have not proven reliable. A motor conduction study has been described but is not generally available for clinical use and has no utility in females. Selective nerve blocks may be diagnostic as well as therapeutic. Injection of the ilioinguinal and iliohypogastric nerves will not impact symptoms due to genitofemoral neuropathy, whereas L1 and L2 root blocks should provide relief. A transpsoas genitofemoral nerve block has also been described. Treatment options include avoidance of aggravating positions and activity, local measures such as ice, topical anesthetics, or capsaicin cream, and soft tissue techniques for scar release. Biofeedback and transcutaneous electrical stimulation may also be useful. Oral medications include anticonvulsants, tricyclic antidepressants, and nonsteroidal antiinflammatory medications, as well as narcotics. When conservative measures are inadequate, nerve ablation or surgical excision may be indicated. Before selecting an approach, consideration must be given to potential involvement of the nerve in the retroperitoneal space or the preperitoneal segment of the genital branch, as interruption distal to that site will not provide relief.
See also: Femoral Nerves
Further reading Amid PK (2011) Surgical treatment of chronic groin and testicular pain after laparoscopic and open preperitoneal inguinal hernia repair. Journal American College Surgeons 213: 531–536. Ducic I, Moxley M, and Al-Attar A (2006) Algorithm for treatment of postoperative incisional groin pain after cesarean delivery or hysterectomy. Obstetrics & Gynecology 108: 27–31. Parris D, Fischbein N, Mackey S, and Carroll I (2010) A novel CT-guided transpsoas approach to diagnostic genitofemoral nerve block and ablation. Pain Medicine 11: 785–789. Rab M, Ebmer J, and Dellon AL (2001) Anatomic variability of the ilioinguinal and genitofemoral nerve: Implications for the treatment of groin pain. Plastic and Reconstructive Surgery 108: 1618–1623.
Encyclopedia of the Neurological Sciences, Volume 2
doi:10.1016/B978-0-12-385157-4.00661-8