A 24-year-old man is being evaluated for a nerve block procedure. The patient has had intermittent burning and stabbing pain in the left groin since undergoing mesh repair of an inguinal hernia a year ago. The pain is often brought on by physical activity and coughing. He has no other medical conditions and takes no medications. Vital signs are within normal limits. On physical examination, there is no weakness of anterior abdominal or lower extremity muscles. Lightly touching the upper medial thigh or upper part of the scrotum elicits burning pain. Cremasteric reflex is normal. The clinical diagnosis is entrapment of a nerve traversing the superficial inguinal ring with the spermatic cord. Blockade of which of the following nerves with a local anesthetic injection is most likely to relieve this patient's symptoms?

Question

A 24-year-old man is being evaluated for a nerve block procedure.  The patient has had intermittent burning and stabbing pain in the left groin since undergoing mesh repair of an inguinal hernia a year ago.  The pain is often brought on by physical activity and coughing.  He has no other medical conditions and takes no medications.  Vital signs are within normal limits.  On physical examination, there is no weakness of anterior abdominal or lower extremity muscles.  Lightly touching the upper medial thigh or upper part of the scrotum elicits burning pain.  Cremasteric reflex is normal.  The clinical diagnosis is entrapment of a nerve traversing the superficial inguinal ring with the spermatic cord.  Blockade of which of the following nerves with a local anesthetic injection is most likely to relieve this patient's symptoms?

Quizplus · Accepted Answer

11ec160b_35af_60b2_9249_ff9680d53b1f_MD0001_00 Inguinal hernia is protrusion of abdominal contents through the abdominal wall above the inguinal ligament, via either the deep/internal inguinal ring and inguinal canal (indirect hernia) or the superficial inguinal ring (direct hernia). Surgical repair involves returning the herniated tissues to the abdomen and closing the defect. Synthetic mesh (eg, polypropylene) is often placed at the site of the defect to reduce tension on the tissues and reduce the risk of recurrence. Postherniorrhaphy neuropathy is a recognized complication of hernia surgery. Regional nerves may be injured during the procedure (eg, transection, cautery) or by postoperative inflammation and fibrosis (ie, nerve entrapment). This patient has a neuropathy of the ilioinguinal nerve presenting with pain and allodynia (ie, pain caused by normally nonpainful stimuli). The nerve enters the inguinal canal anterior to the internal ring and follows the spermatic cord (round ligament in women) to the superficial ring; it gives off sensory branches to: Anterior scrotum (labia majora) Base of the penis (mons pubis) Medial thigh (Choice A) The femoral nerve courses deep to the inguinal ligament; injury during inguinal hernia repair is possible but less common than ilioinguinal injury. Femoral nerve injury causes sensory symptoms in the anterior thigh and motor weakness of the quadriceps. (Choice B) The genital branch of the genitofemoral nerve passes through the inguinal canal; injury may cause pain at the anterior scrotum. However, the cremasteric reflex is mediated primarily by the genitofemoral nerve and is typically diminished when the nerve is injured. (Choice C) The anterior branch of the iliohypogastric nerve is vulnerable to injury where it pierces the anterior abdominal musculature superior to the superficial inguinal ring. However, it does not follow the spermatic cord, and sensory symptoms involve the skin overlying the suprapubic/hypogastric region, not the groin. (Choice E) The obturator nerve innervates the medial compartment of the thigh. Injury presents with weakness of hip adduction and decreased sensation at the medial thigh; it may be injured in pelvic (eg, bladder) surgery but is not at risk in hernia repair. Educational objective: Postherniorrhaphy neuropathy refers to groin pain following hernia repair due to injury involving the cutaneous nerves of the lower abdomen/groin. Neuropathy of the ilioinguinal nerve presents with pain and allodynia in the anterior scrotum (labia majora in women), base of the penis (mons pubis), and medial thigh.

A 24-Year-Old Man Is Being Evaluated for a Nerve Block