Ilioinguinal Nerve

Original Editor - Khloud Shreif

Top Contributors - Khloud Shreif, Candace Goh and Ines Musabyemariya

Description

The ilioinguinal nerve is a mixed nerve that originates from the lumbar plexus. It emerges near the outer edge of the psoas major muscle and travels downward through the front of the abdominal wall. It stays beneath the peritoneum and passes in front of the quadratus lumborum muscle, continues downwards and obliquely across its surface, then it passes over the anterior surface of the iliacus muscle until it reaches the iliac crest. From there, it traverses through the transversus abdominis and the internal oblique muscles. As it continues, it becomes visible near the groin area, passing through the superficial inguinal ring just in front of the spermatic cord in males.

Root

Originate from the anterior rami from L1 nerve roots in the lower back, in some cases it receives contribution from T12 or l2 in other cases upon its origin.

Branches

Ilioinguinal nerve gives motor branches to the transversus abdominis and the internal oblique muscles when it passes through the posterior abdominal wall.

After existing though superficial inguinal ring it gives sensor branches, anterior labial nerve in females and anterior scrotal nerve in male.

Function

Motor

The motor innervation to transversus abdominis and the internal oblique muscles

Sensory

Anterior labial nerve in females gives cutaneous innervation to anterior one-third of the labium majora, mons pubis, and root of clitoris.

Anterior scrotal nerve in males gives sensory innervation to skin of the anterior 1/3 of the scrotum and the root of the penis

In addition cutaneous innervation to the superior medial thigh.

Clinical relevance

Ilioinguinal nerve injuries/ neuropathy frequently occur following abdominal surgery, abdominal wall trauma, accidentlly during surgery because of traumatic trochar from laparoscopic surgeries, post hysterectomy or during inguinal hernia repairs. However, when the motor branches of the nerve are affected, it can result in weakened transversus abdominis and internal oblique muscles, potentially leading to the development of inguinal hernias.

Furthermore, ilioinguinal nerve entrapment may also occur due to the presence of sutures in close proximity, leading to sensory disturbances along the nerve's path, a condition known as nerve entrapment.

Ilioinguinal neuralgia is one of the common causes for chronic lower abdominal and anterior pelvic pain.

Inguinodynia is a chronic or persistent groin pain, defined as pain beyond three months after inguinal hernia surgery.

Assessment

Physical Examination

The ilioinguinal nerve typically manifests its symptoms through cutaneous manifestations in the nerve distribution without causing weakness. These symptoms often include a sharp or burning sensation that worsens with lifting or bending. While tenderness points may be observed near the ASIS (anterior superior iliac spine), it is not a definitive diagnostic sign. Additionally, patients may adopt a flexed posture while walking or sit with one leg extended to minimise nerve compression in the groin. Activities or movements involving hip extension may exacerbate the symptoms. For confirmation some diagnostic procedures may be carried out:

Diagnostic ultrasound we can track the nerve when it becomes superficial down to the superficial inguinal ring a guided injection using ultrasound or CT scan is very helpful for diagnosis.

Electrodiagnostic study to exclude other causes like; radiculopathy from lumbar or lumbar plexus injury or to support the diagnosis.

Treatment

Medical Treatment

Nerve block: nerve block guided imaging ultrasound proved to be effective for treatment of ilioinguinal neuralgia and approximately 55–70% showed a beneficial analgesic post-inguinal hernia surgery.

NSAIDs, anti-inflammatory, antidepressants, opioids, and antiepileptics for inguinal neuralgia and inguinodynia.

Radiofrequency ablation is effective for long-term pain relief and poses a low risk of neuroma formation.

Surgical Intervention

It can be carried after failure of all conservative treatment, and it is always preferred to be done not before 6- 12 after the initial surgery that caused neuralgia.

Extraperitoneal excision of the nerve for entrapment-caused cases and is often considered the preferred treatment.

For cases of generalised refractory inguinodynia, triple neurectomy that involves removing the proximal branches of the ilioinguinal, genitofemoral, or illiohypogastric nerves, is a more definitive treatment.

Physical Therapy Intervention

• Scar tissue mobilisation and soft tissue mobilisation/ myofascial release if there was a scar from a previous surgery near to the nerve.
• Transcutaneous electric nerve stimulation and acupuncture can control symptoms of the ilioinguinal neuralgia.