The Impact of Perioperative Gabapentin on Chronic Groin Pain After Inguinal Hernia Repair

A common source of morbidity after IHR is chronic groin pain(CGP), usually defined as pain lasting longer than 3 months. Gabapentin is an anticonvulsant that is also of benefit in the treatment of neuropathic pain. We propose a randomized, double-blind, placebo controlled study of the effect of gabapentin on CGP after IHR. Their pain will be assessed with a visual analogue scale. For those reporting pain, the need for pain medication, or other treatment, and the effect of pain on their quality of life will be recorded.

Over 500,000 inguinal hernia repairs(IHR) are performed in the United States annually. This is also one of the most common operations performed on the primarily young, male Active Duty population. A common source of morbidity after IHR is chronic groin pain(CGP), usually defined as pain lasting longer than 3 months. The incidence of CGP varies widely in published reports, but in the majority it is 25 to 30%. A major etiology of CGP is thought to be injury to inguinal nerves during surgery. Gabapentin is an anticonvulsant that is also of benefit in the treatment of neuropathic pain. Numerous studies have shown that gabapentin can decrease perioperative pain in patients undergoing surgeries such as hysterectomy, cholecystectomy and spine surgery. Doses and medication regimens varied in these studies, One study in patients undergoing IHR who received a single dose of gabapentin preoperatively, showed a decrease in postoperative pain and in reported pain scores in the first 6 months. We propose a randomized, double-blind, placebo controlled study of the effect of gabapentin on CGP after IHR. Patients will be given placebo or gabapentin. Those given gabapentin, will be given 300 mg orally three times daily for a total of six doses with the first dose given on the morning of surgery. Patients will be evaluated preoperatively and at 1, 6, 12 and 24 months after surgery. Their pain will be assessed with a visual analogue scale. For those reporting pain, the need for pain medication, or other treatment, and the effect of pain on their quality of life will be recorded.

Patients randomized to the placebo-group were administered placebo-pills orally one hour prior to surgery, then three times a day for a maximum of 6 total doses.

Patients randomized to the gabapentin-group were administered 300 mg orally one hour prior to surgery, then three times a day for a maximum of 6 total dose.

Gabapentin is a structural analogue of GABA that decreases activation of voltage-activated calcium channels which may decrease release of excitatory neurotransmitters such as glutamate. Its analgesic mechanisms have been utilized effectively for the treatment of chronic pain in several disorders such as cancer, fibromyalgia and diabetic peripheral neuropathy.

Inclusion Criteria: Male patients 18 years of age or older undergoing initial inguinal (bilateral or unilateral) hernia repair by any method (i.e. laparoscopic or open surgery) Exclusion Criteria: Age less than 18 years of age, recurrent hernias, emergency operations, already taking gabapentin, allergy to gabapentin, pre-existing chronic pain or psychiatric disorder

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