Causes of Postoperative Pain Following Inguinal Hernia Repair: What the Literature Shows
For more than 20 years, there has been widespread international acceptance of the routine use of prosthetic mesh for primary inguinal hernia repair. Randomized controlled clinical trials have shown unequivocally a dramatic reduction in recurrence rates as compared to primary sutured repairs when the repairs have been done outside specialty centers, ie, using the Shouldice repair. However, postoperative pain syndromes have been recognized as a bona fide problem with mesh repairs. This issue has been greatly enhanced by concerns raised by advocacy groups, medico-legal problems, and cost containment among institutions. This article will explore the relationship between prosthetic materials and post-herniorrhaphy pain syndromes and identify subsets of patients and conditions whereby it may be better not to use mesh prostheses. This summary of facts and recommendations hopefully will provide a template for future hernia repairs and elevate the quality of surgical care.
Materials and Methods
To study the link between postoperative pain among inguinal hernia patients (inguinodynia) and prosthetic mesh, the author performed a retrospective online literature search from 1998 to 2011. The review included an analysis of different open and laparoscopic hernia repair techniques: non-mesh versus open mesh and laparoscopic mesh repairs were evaluated regarding the incidence of postoperative chronic pain. Risk factors associated with postoperative inguinal herniorrhaphy pain were listed and substantiated by published research results. These factors addressed the issues of preoperative pain, anesthesia, fear of pain, prolonged operative times, wound infections, hemorrhage, timing of surgery, and surgeon experience. Subsets of patients where prosthetic materials should not be used were identified. Ultimately, a summary of comprehensive findings was discussed referencing whether mesh did indeed cause pain following hernia repair, the mechanism of pain from mesh, and those recommendations as to how best avoid mesh pain.
Classification of Postoperative Pain
Three separate types of chronic postoperative pain have been delineated including somatic or nocioceptive pain, neuropathic pain, and visceral pain (Table 1). A common denominator in each type of pain is the presence of mesh. Somatic or nocioceptive pain was found to be the most common type of pain. Usually, it emanated from preoperative pathological causes. These may have included previous ligament injury, mesh injury, and new ligament or muscle injury caused by surgery. In addition there may be an aggressive scarification reaction, osteitis pubis, or a vigorous inflammation of the pubic tubercle. Lastly, a significant offender has been reactions to the prosthetic mesh/material.
The second type of pain is neuropathic pain. This involves direct nerve damage or injury. Certain intraoperative problems and/or technical issues may have transpired, including incorporation of nerve/nerves with staples, sutures, or mesh. Those nerves commonly involved included the ilioinguinal, iliohypogastric, genital branch of the genito-femoral nerve, and lateral femoral cutaneous nerve.
Mesh placement will usually negatively impact the genital branch of the genito-femoral nerve. Femoral nerve injury involving either the motor, sensory, or both functions may have been negatively impacted. A routine finding and phenomenon is the overlapping of the nerve distribution in the groin along with the symptoms and signs of the specific nerve injury.
The third type of chronic postoperative pain is visceral pain. The etiology may be of intestinal origin. Also, properitoneal tissue compromise may occur emanating from the mesh. Dysuria or difficulty starting the stream of urine may contribute to visceral pain. Other genitourinary problems such as dysejaculation syndrome (customarily predating surgery) and erectile dysfunction (ED) may play a part in visceral pain. However, one must be aware of the fact that erectile dysfunction cannot occur secondary to groin hernia surgery. Those nerves responsible for ED originate from the second through fourth sacral nerve roots, and not through the sensory nerves in the groin. Therefore, it is anatomically impossible to create impotence from groin hernia surgery, despite that which a plaintiff’s attorney may say.
Definition of Chronic Postoperative Groin Pain
Chronic postoperative groin pain has been defined as pain lasting more than 30 days and interfering with the patient’s activities of daily living or work activities. Mesh inguinodynia is a phrase coined by Heise and Starling in 19981 and refers to pain following hernia repair. This term is also well described and discussed by Mazin.2 Courtney, Duffy, et al3 studied a series of 5,506 patients operated on over 1 year. All types of repairs were included. According to this report, 3% of their patients experienced severe pain after 3 months; 8% of the patients required further surgery for various causes; and 15% went to pain clinics. Chronic pain affected walking, work, sleep, interpersonal relationships, and mood.
In their sentinel study, Bay-Nielsen, Perkins, and Kehlet4 reported up to 37% of patients having chronic pain after inguinal herniorrhaphy. They cited no differences in regard to types of hernias, different surgical techniques, or different types of anesthesia. Greater than 50% of those patients with chronic pain had associated functional impairment.
Whereby the phrase “mesh inguinodynia” was coined by Heise and Starling in 1998, they questioned whether mesh had caused pain syndromes or helped to eliminate them. In their study of 117 reoperated patients, 20 had a primary mesh herniorrhaphy and 3 had laparoscopic repairs. Two patients required mesh removal 1 to 2 years postoperatively. Sixteen patients had removal of the mesh and ilioinguinal or iliohypogastric nerve removal. Those patients undergoing mesh removal and neurectomy had a higher percentage (62%) of good to excellent results as compared to those patients undergoing mesh removal only (50%).