Ilioinguinal Nerve Entrapment and Pain in Endometriosis (case 1)

SB is an 18-year-old G0 female who presented with a long-standing history of perimenstrual pelvic pain and diarrhea thought to be due to endometriosis. Her menses are irregular (1-3 month intervals). Laparoscopy in October 1995 demonstrated diffuse peritoneal endometriosis with clear vesicular lesions. Excision of the uterosacral ligaments was carried out. Postoperatively, she received two doses of medroxyprogesterone depot and was then switched to oral contraceptives. Her pain was well controlled with medroxyprogesterone depot but returned when she was switched to oral contraceptives. She was switched back to medroxyprogesterone depot with resolution of pain.

In October 1996, she experienced a recurrence of her pain. She described the pain as left lower quadrant, constantly aching, occasionally knife-like stabbing, without radiation. The pain increased with val-salva or sneezing. She was unable to continue school or participate in normal activities. She is not sexually active. She had no genitourinary or gastrointestinal symptoms, and a CT of the pelvis was normal.

Physical examination revealed diffuse lower abdominal tenderness without rebound or evidence of hernia or disc disease. Pelvic examination revealed a virginal introitus, the small anterior uterus having no adnexal masses. Both ovaries were inactive and non-tender on transvaginal ultrasound evaluation.

The patient underwent endoscopic evaluation showing a single area of ‘powder-burn’ endometriosis on the rectum. There was no evidence of vesicular, red or white endometriosis. There were adhesions from the omentum on the posterior wall of the uterus and between the right ovary and the pelvic sidewall. Adhesions and the powder burn were excised.

Immediately following the excision, she noted complete resolution of the pain. However, a large area of bruising was evident at the left flank laparoscopy port site which extended to the level of the hip. However, approximately 6 weeks later, she noted increasingly severe, suprapubic, sharp, twisting pain. Examination and urine analysis were unremarkable. The patient was placed on a GnRH agonist.

When seen 4 months postoperatively, her pain had increased in intensity and was now focused in the left lower quadrant, with tenderness localised to her port site. Add-back therapy was started; the patient was placed on gabapentin and received injections of local anaesthetic and methylprednisolone at the port site. Although initial relief was achieved, she experienced fainting spells which were related to gabapentin. The differential diagnosis included ilioinguinal nerve entrapment and port site endometriosis.

At surgery, a large amount of scar tissue was seen at the port site along the line between the anterior superior iliac crest and the pubic tubercle. On dissection, the ilioinguinal nerve was seen exiting through the internal oblique muscle directly into the scar tissue. The nerve tissue was excised and a frozen section confirmed nerve excision.

The patient noted immediate relief in the recovery room. She has been on oral contraceptives postoperatively and has been pain-free.

January feedback

Further to his case histories on ilioinguinal nerve entrapment and pain, Mark Perloe replies to your queries.

User query:
The pain was due to entrapment of the ilioinguinal nerve. Rather than doing extensive surgery, just cutting the nerve might give the same result as far as the pain is concerned.
CP Rai
New Delhi, India

Mark Perloe replies:
In fact that is what was done. The nerve is rarely easily identifiable as it would be in a patient with no prior surgery. Identification of the nerve is often complicated by the degree of scar tissue surrounding the nerve path as it exits between the internal and external oblique muscles. Unless a careful dissection of the nerve is performed, and frozen section used to confirm that nerve tissue has been obtained, the procedure may not be successful.