Neuropathic pain involves damage or injury to the nerves of the inguinal canal, particularly nerves running in the anterior (inguinal) and posterior (preperitoneal) space. There are five sensory and somatic nerves that are susceptible to injury during inguinal hernia repair. These nerves are iliohypogastric, ilioinguinal, genital and femoral branch of the genitofemoral, and the lateral femoral cutaneous nerve.

The anterior approach to repair of inguinal hernia includes the Bassini, McVay, Shouldice, and Lichtenstein repairs. These repairs may expose the nerves running in the inguinal canal (iliohypogastric, ilioinguinal, and genital branch of the genitofemoral) to injury or entrapment. Recurrence after open (anterior) inguinal hernia repair occurs in up to 6 % of patients and pain is associated with 15 % of repairs [9].

Minimally invasive inguinal hernia repair, laparoscopic transabdominal preperitoneal (TAPP) and totally extraperitoneal repair (TEP), is associated with a recurrence rate of 3 % and postoperative pain occurs after 2 % of repairs [9]. These repairs place mesh posterior to the rectus fascia, in the preperitoneal space. The “triangle of pain” is outlined as inferior to the inguinal ligaments; the apex is the internal ring, and anterolateral to the gonadal vessels [4]. The lateral femoral cutaneous nerve, femoral nerve, and femoral and genital branch of the genitofemoral nerves lie in this region [5]. Placement of tacks in the triangle of pain can inadvertently entrap the nerves.

Pain and recurrence after inguinal hernia repair are related to a combination of patient-related risk factors, technical considerations, and operative approach. Technical errors include inadequate mesh coverage, mesh folding, and mesh migration. Burcarth et al. recommend that females undergo laparoscopic repair of inguinal hernias in order to evaluate an unappreciated femoral hernia. Smoking is associated with impaired wound healing due to hypoxia and decreased collagen formation [10]. Table 22.2 lists the preoperative, perioperative, and postoperative risk factors associated with pain after inguinal hernia repair [1, 4, 5, 11].

Evaluation of recurrence when pain is the presenting symptom after inguinal hernia repair should begin with a thorough history and physical exam. The history should include the frequency, location, and triggers of pain. The physical exam should focus on a bulge, fascial defect, and reproducible pain. The operative report from the previous surgery should be reviewed, including the type of repair, size of the defect, size and type of mesh, handling of nerves, and type of fixation. Diagnostic imaging—ultrasound, computed tomography scan, or magnetic resonance imaging—supplements the management, excludes recurrence or meshoma, and assists in the diagnosis [4].

Treatment of postoperative pain involves a multidisciplinary approach, including medications, behavior modification, and therapeutic intervention. Courtney et al. found that 30 % of patients have resolution of postoperative inguinal hernia repair pain, 45 % have reduced pain, and 25 % continue to have chronic pain [12]. A period of watchful waiting with symptomatic treatment with a multimodal therapy that includes behavior modification, NSAIDs, and opioid medications is recommended. Additionally, a multidisciplinary group approach that consists of the primary care provider and a dedicated pain specialist (anesthesiologist, neurologist, psychiatrist) is recommended. Adjunctive modalities such as nerve stimulators, steroid injections, or nerve blocks can be both diagnostic and therapeutic. Specific to this subgroup of patients with pain in the presence of a known recurrence, it is important to characterize the potential etiologies of pain so that all contributing factors can be addressed at the time of remedial surgery for both recurrence and pain.