Genitofemoral Nerve

Genitofemoral nerve anatomy

Gross anatomy

Genitofemoral nerve is a branch of the lumbar plexus. it is formed from branches of L1 and L2 spinal nerves. The nerve forms in the substance of the psoas major muscle.

The nerve passes down in the substance of psoas major muscle and emerges on its anterior surface, deep in the fascia. Afterwards it descends in the retroperitoneum. On the left side, it passes the left ureter, gonadal vessels, left colic artery and inferior mesenteric vein. On the right side the nerve passes deep to the right ureter, gonadal vessels and the ileocolic artery and vein. On both sides the nerve perforate the psoas fascia and divide in to genital and femoral branches ^[1].

Innervation zones of genitofemoral nerve in males.
Image source: cotswoldclinics.com

Branches and innervation zones

Genitofemoral nerve divides into genital nerve and femoral nerve.

Genitofemoral nerve in females
image source: wiki.ahuman.org

Genital branch further goes in the inguinal canal and goes through the inguinal ring.

In men, it goes along with the spermatic cord and supplies motor fibers to cremaster and dartos muscles. It supplies the sensory fibers to the spermatic fascia and tunica vaginalis of the testis. It also provides skin sensation to the upper anterior portion of the scrotum.
In women, the nerve goes along with the round ligament of the uterus and provides innervation to pubic skin and large labia.

Femoral branch descends further down and enters the femoral sheath beneath the inguinal ligament. There it lies anterolateral from the femoral artery. The nerve supplies innervation to the skin of groin between the middle part of inguinal ligament (the femoral triangle) ^[1,2].

Functions of genitofemoral nerve

In women, the genital branch of genitofemoral nerve supply the sensory fibers to labia majora and pubic mound. In men, the branch supplies motor fibers to cremaster and dartos muscles, which elevates and lowers the testes. The sensory fibers from the nerve in upper male thigh react to gentle stimulation and signal the sensory fibers that cause the testicle muscles to contract and raise the testes.

The femoral branch for both genders have sensory perception function ^[2].

Genitofemoral nerve pain

What is genitofemoral neuralgia?

Genitofemoral neuralgia is one of the most common causes of pain in the lower abdomen and pelvis. There are many possible causes for nerve pain:

Injury
- Groin injury
  - Usually cuts, lacerations or abrasions
- Inguinal canal injury
  - Blunt injury or sprain of inguinal ligament
- Lower-back injury
  - Whiplash injury
  - Weightlifting
Conditions of the spine
- Stenosis
- Spinal tumor or metastasis
Abscess in the psoas muscle
Pelvic tumor
Surgery
- Usually after inguinal hernia repair
- Can be caused by direct injury or scar tissue forming
Other conditions that can cause nerve entrapment, like Poliomyelitis^[3,4]

Symptoms of genitofemoral neuralgia

The pain can be acute- lasting for less than 3 months or chronic, lasting 3 to 6 months or more. The most common symptoms are:

Pain in the innervation are of both genital and femoral branch
In males, the pain is spread into scrotum and in females- labia majora
The pain from the femoral branch never spreads further than the knee joint
Pain is usually burning, stabbing or neuropathic
Pain is worsened by extension of the lumbar spine which puts traction to the nerve ^[4]

Diagnosis of genitofemoral neuralgia

Physical findings in this condition mostly consist of sensory deficit in the inner thigh, and base of the scrotum (for men) or labia majora (women). Sometimes weakness of the anterior abdominal wall musculature can be found. The patient might assume a bent-over position. Tinnel’s sign is often positive- when gently tapping over the nerve, the patient will feel pain, tingling or “pins and needles” sensation.

Imaging studies can be performed to find a possible cause for nerve pain. CT and MRI imaging can show nerve entrapment in the spine, as well as scar tissue in inguinal canal ^[3].

Blood analyses should be performed to rule out infection and abscess. Ultrasound can also be performed to rule out nerve obstruction and intra-abdominal pathologies ^[4].

M.Psoas abscess.
Image source: myvmc.com

Treatment

The approach in treating genitofemoral neuralgia, is to initially try out non-invasive methods, before using invasive ones. Medications that can be used to treat pain are:

Acetaminophen
Non-steroid anti-inflammatory drugs
Local anesthetic sprays and ointments
Corticosteroids in small doses

If these medications give no pain relief, stronger medications can be used like:

Opioids- tramadol, vicodin, oxycodone
Antidepressants
Anticonvulsants

Other methods can also be used:

Tactile stimulation
Physical therapy
Trigger point injection
Cryo-nerve ablation
Psychotherapy, in case the pain is secondary to mental disturbances
Relaxation techniques

In case medications do not treat the pain properly, the next step is to perform genitofemoral nerve block. It can ensure dramatic pain relief. In case the femoral nerve block does not work, epidural steroid injection of the L1-L2 segments can be performed. Also, a promising treatment option is pulse radiofrequency ablation ^[5].

The underlying cause of genitofemoral neuralgia should be found before starting any treatment. in case the cause of the pain is due to spinal deformation or tumor, surgery is indicated.

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References

Gross anatomy: https://radiopaedia.org/articles/genitofemoral-nerve
Functions: http://www.healthline.com/human-body-maps/genitofemoral-nerve
Genitofemoral neuralgia: https://www.epainassist.com/pelvic-pain/genitofemoral-neuralgia
Physical examination: http://www.gotpaindocs.com/gentfmrl_nurlga.htm
Nerve block: http://file.scirp.org/pdf/OJAnes_2013072614503802.pdf

Greenstick Fracture