Post-herniorrhaphy groin pain

INTRODUCTION — Pain following hernia surgery is common but should subside within an expected time interval of approximately two months. For many patients, some degree of pain persists, and some patients develop moderate-to-severe pain that can be disabling or interfere with sexual function [1-3]. A presumptive diagnosis of post-herniorrhaphy neuralgia can be made when pain persists for more than three months following hernia repair and is not related to other causes.

The clinical features, diagnosis, and management of persistent pain following hernia repair and surgical treatment of post-herniorrhaphy neuralgia will be reviewed here. The general issues surrounding hernia repair, including measures for preventing post-herniorrhaphy pain, are discussed elsewhere. (See "Overview of treatment for inguinal and femoral hernia in adults" and "Laparoscopic inguinal and femoral hernia repair in adults" and "Open surgical repair of inguinal and femoral hernia in adults".)

NERVES OF THE GROIN — The cutaneous nerves of the lower abdomen and groin that are most frequently implicated in the etiology of persistent groin pain following hernia repair include the ilioinguinal, iliohypogastric, genitofemoral, and lateral femoral cutaneous nerves (table 1). These nerves arise from the lumbar plexus and provide cutaneous sensory innervation for the groin, upper hip, and thigh regions (figure 1) [4-7].

●The ilioinguinal, iliohypogastric, and lateral femoral cutaneous nerves travel along the anterior surface of the quadratus lumborum, and the genitofemoral nerve runs along the anterior surface of the psoas major muscle before piercing the abdominal wall (figure 2A-B).

●The ilioinguinal nerve emerges lateral to the internal ring (figure 3) traveling toward the external ring [8]. The anterior branch of the iliohypogastric nerve is located more medially between the external oblique aponeurosis and the underlying internal oblique muscle (figure 3).

●The genital branch of the genitofemoral nerve exits the retroperitoneum at the internal inguinal ring to run through the inguinal canal on the anterior surface of the spermatic cord (figure 3). The lateral femoral cutaneous nerve is less commonly injured but may be exposed by dividing the inguinal ligament (figure 2A) and the lateral fibers of internal oblique aponeurosis.

The iliohypogastric, ilioinguinal, and genital branch of the genitofemoral nerves are encountered during anterior, open hernia repair (figure 3). (See "Open surgical repair of inguinal and femoral hernia in adults".)

With a laparoscopic or preperitoneal approach, the lateral femoral cutaneous nerve, femoral branch of the genitofemoral nerve, iliohypogastric nerve, and, potentially, the femoral nerve are encountered (figure 4). During laparoscopic repair, the ilioinguinal nerve is at risk lateral to the internal ring and the genitofemoral nerve medial to the ring. The iliohypogastric nerve is vulnerable to injury during laparoscopic mesh fixation [9-11]. Less commonly, injury to the lateral femoral cutaneous nerve and the femoral nerve can occur [12-14]. (See "Laparoscopic inguinal and femoral hernia repair in adults".)

EPIDEMIOLOGY AND RISK FACTORS — Persistent pain following groin hernia surgery is relatively common. Up to one-half of patients report some degree of residual groin pain at one year of follow-up, but up to 15 percent complain of moderate-to-severe and possibly disabling pain [1,2,15-20]. In a survey of 2500 Swedish patients two to three years after primary surgery for groin hernia, 30 percent reported some residual groin pain, and 11 to 14 percent reported that the pain was severe enough to interfere with activities (sitting, walking) [15]. A prospective study that included 781 elective primary open hernia repairs found that persistent pain to any degree occurred in 16.5 and 16.1 percent of patients at six months and five years, respectively, after hernia repair; however, moderate-to-severe pain was present in only 1.2 and 1.5 percent [20].

Retrospective reviews have identified the following risk factors for persistent pain following groin hernia surgery [3,15,20-27]:

●Younger age

●History of preoperative pain

●Interval less than three years from a prior surgery

●Severe early postoperative pain

●Postoperative complications

●Preoperative sensory disorder

●Female sex

●Iliohypogastric nerve excision during hernia repair

●Recurrent hernia repair

●Anterior hernia repair

Younger patients may be more likely to develop chronic post-hernia pain [22,23]. A survey of 351 patients who underwent inguinal hernia surgery identified age as the strongest risk factor for developing persistent pain [23]. The incidence of persistent pain was 58 percent for those less than 40 years of age but 14 percent for those over 60. Physical activity and type of employment were speculated to play a role in this difference.

Preoperative pain or chronic pain near the surgical site predisposes to the development of chronic neuropathic pain following hernia surgery. This phenomenon has also been described following amputation, breast surgery, thoracotomy, and in patients with herpes zoster [3,23,24]. In a prospective study that included 781 elective primary hernia repairs, significantly more patients with preoperative pain experienced chronic groin pain at six months and five years postoperatively compared with those who did not (22 and 21 percent versus 13 and 14 percent, respectively) [20].

Patients with smaller hernias are at a higher risk of developing chronic postoperative inguinal pain after hernia surgery. In a large registry-based study of close to 58,000 patients, chronic pain occurred more frequently (odds ratio 1.350, 95% CI 1.180-1.543) after repair of European Hernia Society (EHS) I hernias (<1.5 cm) versus EHS II hernias (1.5 to 3 cm) [28]. The etiology of this observation is unclear but may be related to different patient expectations (patients with smaller hernias expect to be pain free; those with larger hernias expect to be hernia free).

Higher levels of acute postoperative pain also predict persistent pain weeks to months after surgery [3,25,26]. Complications such as recurrent hernia, postoperative hematoma, and infection may also play a role [27,29].

The frequency of persistent postoperative pain may be higher following open hernia repair, particularly with an anterior approach, compared with laparoscopic or robotic hernia repair (ie, posterior approach) [29-31]. However, the reported data are not consistent [32].

Sensitivity to nociceptive pain differs from one patient to another and may be related to an inherited susceptibility to the generation and experience of pain, as well as response to analgesics [3]. Women may also be more predisposed to a higher level of postoperative pain compared with men [3]. Psychological and stress-related factors such as depression and anxiety may also contribute [33].

Groin hernia surgery in women is less frequently studied than in men. In a Swedish Hernia Register study of 4021 women, 18 percent reported chronic pain affecting daily activity at one year after groin hernia repair [34]. More women had chronic groin pain than men (odds ratio 1.3, 95% CI 1.16-1.46). High body mass index, high American Society of Anesthesiologists classification, and femoral hernia were risk factors for chronic pain in women, but not surgical methods or emergency versus elective surgery.

PATHOGENESIS — Two distinct mechanisms can result in a perception of pain following surgery. Acute pain is predominantly due to nociceptive and inflammatory stimulation, which lessens over a predictable time interval (typically six to eight weeks). By contrast, chronic neuropathic pain is due to abnormal neural activity and can persist without ongoing inflammation [3]. Thus, if post-herniorrhaphy groin pain persists for more than eight weeks, it is most likely neuropathic in nature and can be due to primary or secondary nerve injuries [1,3,35].

Primary nerve injuries occur at the time of the hernia surgery and may be caused by [36]:

●Complete or partial transection of nerves, which can lead to neuroma formation

●Nerve damage related to manipulation (stretching, crushing, cautery injury)

●Entrapment or impalement of nerves by sutures or staples

Secondary nerve injury following hernia repair results from an inflammatory process adjacent to the nerve, which is most commonly incited by a mesh [36]. When a peripheral nerve comes into contact with a polypropylene mesh, degeneration of the myelin sheath and associated edema and fibrosis can cause nerve damage. This process has been demonstrated in some [37-39], but not all, studies [40]. In addition, wadding of the mesh, or "meshoma," can lead to nerve entrapment [41]. Wadding of the mesh is generally caused by a lack of adequate mesh fixation and/or an oversized mesh that is too large to stay flat [40].

PREVENTION

Mesh choice — Mesh placement is standard in groin hernia repair. The role of mesh in post-herniorrhaphy neuralgia was the subject of a meta-analysis of 23 trials [42]. The prevalence of moderate and severe pain after nonmesh and mesh repairs were similar: a median of 3.5 percent (0 to 16 percent) versus a median of 2.9 percent (0 to 28 percent), respectively. Thus, mesh may be used without fear of causing a greater rate of chronic pain.

A second meta-analysis of 21 trials compared open (Lichtenstein) repair with light (≤50 g/m²) versus heavy mesh (>70 m²) and found that although there was no statistical difference in rates of hernia recurrence and severe pain, the use of a light mesh resulted in a statistical significant reduction in any pain (15 versus 19 percent) and the feeling of a foreign body (12 versus 20 percent) [43]. (See "Reconstructive materials used in surgery: Classification and host response", section on 'Weight'.)

Mesh fixation methods — Although mesh placement is commonly performed in inguinal herniorrhaphy, mesh fixation techniques vary and have been exploited to prevent or reduce postoperative groin pain with differing results:

●The use of absorbable sutures to secure a mesh has been associated with a lower rate and shorter duration of postoperative groin pain, compared with nonabsorbable sutures [44].

●The use of fibrin glue (eg, Tisseel/Tissucol), rather than suture or tack, to secure a mesh has been shown to reduce postoperative pain in patients who undergo both open and laparoscopic repair of inguinal hernias [45-51].

●The use of cyanoacrylate glue (Histoacryl) to secure a mesh did not reduce postoperative pain in patients who underwent open inguinal hernia repairs with the Lichtenstein technique in one randomized trial [52] but reduced short-term pain up to 30 days compared with suture repair in another trial [53]. In the second trial, there were no differences between the groups in terms of complications, chronic pain, and recurrences at one year [53].

●The use of a self-gripping mesh (Progrip) did not reduce the risk of chronic pain compared with a standard mesh secured with sutures [52,54-56]. A meta-analysis of 14 studies found no improvement in postoperative pain or recurrence rate with self-gripping mesh compared with suture-fixed mesh in open inguinal hernia repair [57].

Prophylactic neurectomy — Routine identification and preservation of all inguinal nerves crossing the operative field during open groin hernia repair has been the standard practice [58]. Some authors, however, have advocated routine prophylactic neurectomy to prevent post-herniorrhaphy neuralgia. They argue that inguinal nerves may be damaged during and after open herniorrhaphy from inflammation, entrapment, or contact with mesh [40]. Additionally, preexisting inguinal neuritis may also contribute to post-herniorrhaphy neuralgia [59].

●The ilioinguinal nerve is the most commonly identified inguinal nerve during open hernia repair. In a meta-analysis of 11 randomized small trials, 1031 patients underwent open Lichtenstein repair with or without prophylactic ilioinguinal neurectomy [60]. Compared with nerve preservation, prophylactic neurectomy resulted in significant reductions in the number of patients reporting pain at <3 months (relative risk 0.61, 95% CI 0.4-0.93) and 3 to 12 months (relative risk 0.3, 95% CI 0.2-0.46) and a trend toward fewer patients reporting pain at >12 months (relative risk 0.5, 95% CI 0.25-1.01). Neither sensory changes (eg, numbness) in body areas innervated by the nerve nor surgical complications differed between the two groups.

●The iliohypogastric nerve was the second most commonly identified inguinal nerve during open hernia repair. In the same meta-analysis (three trials involving iliohypogastric neurectomy), 270 patients underwent open Lichtenstein repair with or without prophylactic iliohypogastric neurectomy. Fewer patients reported pain (relative risk 0.69, 95% CI 0.52-0.90) after a prophylactic iliohypogastric neurectomy at <3 months. Patients who had prophylactic iliohypogastric neurectomy did not have increased sensory changes or complications.

Although routine prophylactic neurectomy during groin hernia repair is safe and may reduce the incidence of post-herniorrhaphy neuralgia, it may lead to troublesome sensory changes such as numbness or dysesthesia in some patients. Thus, the choice of groin nerve preservation versus sacrifice should be made individually for each patient after careful discussion of potential outcomes.

CLINICAL FEATURES

History — The patient should be asked about the onset and quality of the pain, pattern of radiation and nature of their pain, and whether any activities or medical therapies have improved the pain or made the pain worse. The history should also include the type of surgery (open or laparoscopic), type of hernia (medial [direct], lateral [indirect], femoral), and whether there were any postoperative complications. In addition, any history of preoperative pain should be sought, including pain related to other prior surgical procedures, particularly if fewer than three years have elapsed prior to the hernia surgery. Men should be asked about pain related to sexual activity, which is reported in up to 7 percent of patients [27,61]. (See 'Epidemiology and risk factors' above.)

Pain onset — Post-herniorrhaphy pain is not necessarily continuous from the time of the hernia repair. Some patients have only mild pain postoperatively or become pain free, only to develop new-onset pain several weeks, months, or even years later [23,62]. In a prospective study that included 781 elective primary hernia repairs, late-onset pain developed following an asymptomatic interval [20]. In the cohort of patients who were pain free preoperatively, 70 percent of those with pain after five years did not have symptoms after six months. Some patients will report recurrent or worsened pain due to the development of resistance to analgesics [36].

Features suggesting neuropathy — Inflammatory pain following surgery tends to subside over an expected time course [3]. Features of inflammatory pain that are rarely present in patients with neuropathic pain include a throbbing quality to the pain and heat hyperalgesia. Inflammatory pain is not associated with sensory or motor deficits.

Clinical features consistent with neuropathy include an episodic, burning, stabbing, or pricking pain sensation with a trigger point [3,36,38,63]. Groin pain is aggravated by activity and hyperextension of the hip and relieved with recumbency and hip and thigh flexion [40]. Touching the wound site, breathing, coughing, and bowel activity can also trigger pain [3]. The pain may radiate to the hemiscrotum, upper leg, or back. Patients may complain of testicular or labial pain due to genitofemoral nerve irritation, and men can have pain with ejaculation [61]. A small number of patients also report numbness over the groin or thigh.

Clinical signs of neuropathy are distributed along the sensory pathway of the affected nerve(s) (table 1), but differentiation of the specific nerve that is the source of pain can be difficult because of the overlap of the sensory innervation in the groin and the presence of scarring [64-66]. Pain may be reproduced (triggered) by tapping the skin medial to the anterior superior iliac spine or over an area of local tenderness. Some patients complain of tenderness at the pubic tubercle [67].

EVALUATION — When post-herniorrhaphy pain persists beyond two months, we suggest performing imaging studies (such as ultrasound, computed tomography [CT], or magnetic resonance imaging [MRI]) to identify non-neuropathic sources of pain (eg, mesh infection or recurrent hernia) that may not be clinically apparent [40,68,69]. We prefer MRI because it is more sensitive and less operator dependent than other modalities (algorithm 1).

Findings on cross-sectional imaging studies (CT or MRI) that may indicate a non-neuropathic cause for persistent pain include fluid collections or identification of displaced mesh, which can be associated with recurrent hernia. (See "Recurrent inguinal and femoral hernia".)

A periosteal reaction or osteitis of the pubic bone may cause pain, and although the etiology may be idiopathic, for patients who have undergone hernia repair, the pain may be related to suture material or staples placed into the pubic tubercle, or rolled-up mesh adjacent to the bone [68]. (See "Osteitis pubis".)

On occasion, imaging studies may identify nerve swelling or anatomic abnormalities that suggest that a nerve has been injured. Sometimes a neuroma, or sutures or staples placed near the course of a groin nerve, may be seen.

DIAGNOSIS — The diagnosis of post-herniorrhaphy neuralgia is primarily clinical and should be suspected in patients who have persistent groin pain beyond six to eight weeks following inguinal hernia repair despite standard pain management. Patients suspected of having post-herniorrhaphy neuralgia should undergo imaging studies to exclude other non-neuropathic causes for the pain (algorithm 1). (See 'Evaluation' above and 'Differential diagnosis' below.)

The clinical triad below supports a diagnosis of post-herniorrhaphy neuralgia:

●Burning or stabbing pain near the incision or region of surgery radiating along a specific groin nerve distribution

●Evidence of impaired sensory perception in the distribution of the groin nerve

●Pain that is relieved by infiltration with anesthetic into the groin nerve (see 'Patients who respond to nerve block' below)

Although a positive response to peripheral nerve block supports a diagnosis of post-herniorrhaphy neuralgia [3], a negative response does not exclude the diagnosis. Because mesh-related fibrosis and inflammation impairs the spread of the injected anesthetic, nerve block may be more sensitive for identifying nerve involvement in repairs that do not involve mesh.

Imaging is useful for identifying other sources of pain that may require more immediate surgical management but does not reliably demonstrate nerve abnormalities related to post-herniorrhaphy neuropathy. Only rarely does imaging identify nerve swelling or other anatomic abnormalities that are consistent with a nerve injury. (See 'Evaluation' above and 'Differential diagnosis' below.)

DIFFERENTIAL DIAGNOSIS — The differential diagnosis for post-herniorrhaphy neuralgia as a cause of persistent postoperative pain includes postsurgical complications such as recurrent hernia, mesh infection/displacement, fluid collection, and osteitis pubis. These may be readily apparent on physical examination but at times may require imaging to exclude them as a source for persistent groin pain. (See 'Evaluation' above and "Recurrent inguinal and femoral hernia".)

Excluding other causes for persistent groin pain can be difficult, particularly if pain was present preoperatively. The differential diagnosis of lower abdominal, pelvic, and scrotal pain includes a myriad of other disorders of the spine, lumbosacral plexus, and peripheral nerves of the lower abdomen and groin region. These disorders are discussed in separate topic reviews. (See "Causes of abdominal pain in adults" and "Overview of lower extremity peripheral nerve syndromes" and "Anterior cutaneous nerve entrapment syndrome" and "Nerve injury associated with pelvic surgery" and "Chronic pelvic pain in nonpregnant adult females: Causes".)

MANAGEMENT — Postoperative pain following groin hernia surgery is common and easily treated with opioids and nonsteroidal anti-inflammatory drugs (NSAIDs). Most often, postoperative groin pain subsides within six to eight weeks. When pain persists beyond three months and is not attributable to another cause, post-herniorrhaphy neuralgia can be diagnosed. We suggest that pain in such patients be managed with multimodal analgesia including a nerve block [3,70]. Other regimens that may be useful in the treatment of chronic pain are discussed elsewhere (algorithm 1) [71]. (See "Approach to the management of chronic non-cancer pain in adults".)

Patients who respond to nerve block — For patients diagnosed with post-herniorrhaphy neuralgia, a groin nerve block should be performed. Groin nerve blocks are performed to control pain and confirm the diagnosis (since nerve block should relieve the pain of neuralgia). (See 'Diagnosis' above and 'Nerves of the groin' above.)

Groin nerve blocks are usually performed by a pain specialist (typically an anesthesiologist) in a chronic pain treatment center but can be performed by a surgeon who is familiar with the technique. During a nerve block, a mixture of a long-acting local anesthetic and a glucocorticoid is injected into the tissue surrounding the affected nerve [72,73]. As an example, one such protocol calls for injection of 5 to 10 mL of 0.25% to 0.5% bupivacaine, combined with 25 mg of hydrocortisone or 20 mg of methylprednisolone. (See "Overview of peripheral nerve blocks".)

In some patients, performing a groin nerve block breaks the pain cycle and cures the post-herniorrhaphy neuralgia. In others, pain recurs after the effect of treatment wears off in a few days. Patients with a positive response to an initial nerve block can be treated with weekly injections until pain relief becomes sustained. For those who fail to achieve a sustained response to repeated nerve blocks, groin nerve sacrifice may be their best option [38].

Patients who initially respond to nerve blocks, but pain recurs — Response to a nerve block, even a transient one, indicates that the pain is neuropathic in origin. If a specific groin nerve block (eg, ilioinguinal or iliohypogastric) is reproducibly effective, but the effect is transient, that nerve can be sacrificed to achieve permanent pain relief. Nerve sacrifice can be accomplished by percutaneous nerve ablation or surgical neurectomy.

Nerve ablation — Nerve ablation is performed in a similar manner to nerve block except that a neurolytic solution such as phenol or alcohol is injected instead of a local anesthetic [38]. Alcohol or phenol injection permanently destroys the offending nerve ending and reduces chronic inflammation caused by the mesh or postoperative fibrosis [74]. Alternative techniques of percutaneous nerve ablation, such as radiofrequency ablation [75,76] or cryoablation [77], have also been described.

The outcomes of percutaneous nerve ablation are less favorable than surgical nerve excision, for nerve ablation only destroys the offending nerve ending(s), and recurrent pain may develop after subsequent nerve regeneration. However, nerve ablation is minimally invasive, does not cause significant side effects, and therefore may be tried first in patients with post-herniorrhaphy neuralgia who are refractory to repeated nerve blocks. Those who respond to a nerve ablation can be spared potential complications of a surgical neurectomy.

Surgery — Based upon observational studies, surgery appears to be the most effective treatment for persistent groin pain in patients with post-herniorrhaphy neuralgia. We suggest surgical intervention when nonsurgical measures including medications and nerve block/ablation have been tried but fail to control pain.

Groin exploration and neurectomy (nerve excision) with mesh removal and replacement is our preferred surgical approach. Other procedures, including neurolysis (freeing the nerve), simple nerve division, and mesh excision alone are associated with higher failure rates than nerve excision [7,70,78].

There is no consensus on the timing for surgical intervention. It may be influenced by the adequacy of the patient's pain control, their lifestyle, and their need to work. Most experts, however, suggest waiting a minimum of six months following hernia repair before attempting a nerve excision [68,79].

Nerve excision — Nerve excision (neurectomy) relieves groin pain in the majority of patients with post-herniorrhaphy neuralgia and is indicated when all other measures to control pain have failed [39,78,80]. Success rates range from 70 to 100 percent [7,38,41,63,65,66,68,78,80-96]. In a small randomized trial (GroinPain), selective neurectomy was three times more likely to be successful in pain relief than repeated nerve blocks (71 versus 22 percent) in patients who developed chronic groin pain after anterior inguinal hernia mesh repair [97].

In patients who develop post-herniorrhaphy neuralgia after an anterior repair, nerve excision, along with possible removal of the mesh and any tacks in the preperitoneal space, is the preferred surgical approach. Nerve excision is also performed prophylactically by some surgeons during hernia repairs as a means to prevent post-herniorrhaphy neuralgia.

Neurectomy involves identification, dissection, and resection of, ideally, the entire length of a nerve, leaving smooth ends to be ligated, cauterized, or buried within muscle [69,81,93]. We prefer to ligate and implant the end of the nerve into healthy muscle or retroperitoneal tissue depending upon the location of the nerve. Open, laparoscopic, and combined approaches to inguinal neurectomy have been described, but there are no trials comparing these approaches [81,83].

Any one or a combination of the groin nerves (eg, ilioinguinal, iliohypogastric, genitofemoral) can be resected during a nerve excision. There is no consensus on whether only the affected nerve or all identifiable nerves in the groin should be excised [40,98]. The response to diagnostic nerve blocks has been used by some to guide selective neurectomy, but others caution that this approach does not guarantee good outcomes [38]. For patients who require surgical treatment for post-herniorrhaphy neuralgia, we suggest performing a triple neurectomy rather than a selective neurectomy.

●Triple neurectomy – A triple neurectomy involves resection of the ilioinguinal, iliohypogastric, and genital branch of the genitofemoral nerves [68,80,93,94]. An extended version of the triple neurectomy also includes excision of the main trunk of the genitofemoral nerve over the psoas major muscle [41,99]. A triple neurectomy relieves chronic groin pain permanently in over 90 percent of patients but causes a complete loss of sensation in the distributions of the resected nerves [63,81,93]. (See 'Nerves of the groin' above.)

●Selective neurectomy – A selective neurectomy removes one or more nerves depending upon intraoperative evidence of nerve involvement (neuroma or entrapment) [82,88]. As an example, ilioinguinal neurectomy alone has been used as an effective treatment for relieving neuropathic groin pain in patients who are diagnosed with ilioinguinal neuralgia by selective nerve blocks [65,85,88,95]. In one study, ilioinguinal neurectomy led to complete pain relief in 15 of 17 patients [65]. In another study, 21 of 23 patients stopped taking pain medications after undergoing a successful ilioinguinal neurectomy [88].

In other studies, although a selective neurectomy avoids the chronic sensory deficit of triple neurectomy, it may not be as effective as a triple neurectomy in relieving chronic pain. In a study of 49 patients who underwent selective neurectomy, complete pain relief occurred in 52 percent, partial pain relief in 24 percent, and no pain relief in 24 percent of patients at 1.5 years [82].

Mesh removal — When performing surgery for post-herniorrhaphy neuralgia, we typically remove the old mesh and replace it with a new one. The new mesh should be placed in the preperitoneal space either through the same open incision or laparoscopically.

Placement of a mesh is an integral part of any groin hernia surgery. Mesh can contribute to postoperative groin pain by causing inflammation or entrapping nerves. On occasion, mesh removal by itself may be effective to relieve groin pain. As an example, a patient with testicular pain and a previous plug-and-patch repair was found to have the mesh engulfing the vas deferens [81]. Removal of the mesh plug along with the vas resulted in complete pain relief. However, removal of hernia mesh alone generally does not lead to lasting pain relief in patients with post-herniorrhaphy neuralgia, and better pain relief can be achieved with mesh removal plus neurectomy compared with mesh removal alone [38].

Mesh removal can predispose patients to developing recurrent hernias. To avoid this sequela, some authors suggest mesh replacement in a location that is opposite the original one [81,83]. In one study of 21 patients who underwent triple neurectomy and removal of the old mesh, a new mesh was inserted laparoscopically if the previous repair was open, or open if the previous repair was laparoscopic [81]. Twenty of 21 patients reported significant improvement or resolution of symptoms at six weeks. However, it is not known how many of the patients developed recurrent hernias.

Patients who have persistent pain — Patients who do not respond to an initial groin nerve block may benefit from a second trial. Those who fail repeated nerve blocks are difficult to manage. While some authorities perform a triple neurectomy with mesh excision, others prefer medical pain management. Medications commonly used to treat chronic neuropathic pain include antiepileptics such as gabapentin or pregabalin and antidepressants such as duloxetine. Medications commonly used to treat postoperative pain, such as NSAIDs and opioids, may not be as effective against chronic neuropathic pain. (See 'Surgery' above and "Pharmacologic management of chronic non-cancer pain in adults", section on 'Pharmacologic therapy for neuropathic pain, or nociplastic or centralized pain'.)

For patients who have persistent or recurrent pain after a surgical neurectomy with mesh excision, nerve stimulation is an experimental treatment that may be effective [82]. (See 'Nerve stimulation' below.)

Nerve stimulation — Nerve stimulation (eg, laparoscopic implantation of neuroprosthesis [LION]) is a procedure that implants a quadripolar electrode in direct contact with the injured nerves on the anterior surface of the psoas and quadratus lumborum muscles behind the kidney and colon [6]. Nerve stimulation has not been widely studied but may be useful in patients who exhibit a limited response to nerve blocks, particularly those with one or more other risk factors for chronic groin pain. Patients who continue to have pain after triple neurectomy and mesh removal may also benefit from nerve stimulation.

Other therapies, such as acupuncture, heat, topical analgesics, and physical therapy, have been tried with varying degrees of success in the short term but with limited efficacy in the long term for relieving chronic groin pain [63,81]. In addition, some clinicians have advocated a more sedentary occupation or lifestyle to avoid aggravation of pain associated with movement [40]. We do not endorse this approach, as reduction in activity levels may lead to poor quality of life and loss of productivity [100].

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Groin hernia in adults".)

SUMMARY AND RECOMMENDATIONS

●Post-herniorrhaphy neuralgia has become a more prevalent complication associated with hernia repair. Although some degree of groin pain following hernia repair is common, up to 10 percent of patients develop moderate-to-severe pain following hernia repair. For some, the pain can be persistent and disabling and may also interfere with sexual function. (See 'Introduction' above.)

●Acute postoperative pain following groin hernia surgery is common and, usually, easily treated with opioids and nonsteroidal anti-inflammatory drugs (NSAIDs). Most often, postoperative groin pain subsides within six to eight weeks (algorithm 1). (See 'Management' above.)

●Postsurgical pain lasting more than eight weeks is mostly, but not entirely, neuropathic in character. Neuropathic pain is due to injury to a nerve or to the elements responsible for nerve transmission. The nerves most commonly implicated in post-herniorrhaphy neuralgia are the ilioinguinal, iliohypogastric, genitofemoral, and lateral femoral cutaneous nerves. Nerve injury can be primary or secondary to an adjacent inflammatory process such as a close association of the nerve with hernia mesh. (See 'Nerves of the groin' above and 'Pathogenesis' above.)

●Risk factors for chronic groin pain following hernia repair include younger age, female sex, postoperative complications (eg, hematoma, infection), recurrent hernia repair, open repair techniques, history of preoperative pain, and an interval of less than three years from a previous surgery. (See 'Epidemiology and risk factors' above.)

●A diagnosis of post-herniorrhaphy neuralgia is suspected in patients with persistent groin pain beyond six to eight weeks following inguinal hernia repair despite standard pain management. The clinical triad of burning near an incision or region of dissection radiating along a specific nerve distribution, evidence of impaired sensory perception in the distribution of that nerve, and pain that is relieved by peripheral nerve block strongly supports a diagnosis of post-herniorrhaphy neuralgia. Imaging studies (computed tomography or magnetic resonance) are used primarily to exclude non-neuropathic hernia-related pathologies or other non-hernia-related diseases in the differential diagnosis (algorithm 1). (See 'Clinical features' above and 'Diagnosis' above.)

●In patients with post-herniorrhaphy neuralgia, we manage the pain with multimodal analgesia including a nerve block (algorithm 1). (See 'Management' above.)

●Response to a nerve block, even a transient one, indicates that the pain is likely neuropathic in origin. If a specific groin nerve block (eg, ilioinguinal or iliohypogastric) is reproducibly effective, but the effect is transient, then that nerve can be sacrificed to achieve permanent pain relief. Nerve sacrifice can be attempted first by percutaneous nerve ablation (algorithm 1). (See 'Patients who initially respond to nerve blocks, but pain recurs' above.)

●For patients who have failed nonsurgical management (including percutaneous nerve ablation), we suggest triple neurectomy rather than excision of fewer nerves, neurolysis (freeing the nerve), or simple nerve division (Grade 2C). Triple neurectomy, which is the combined resection of the ilioinguinal, iliohypogastric, and genitofemoral nerves, permanently relieves chronic groin pain in the majority of patients (up to 95 percent), but with a loss of inguinal sensation. An open, laparoscopic, or combined approach can be used (algorithm 1). (See 'Surgery' above.)

●Patients who have persistent or recurrent pain after surgical neurectomy with mesh removal are difficult to manage. Nerve stimulation is an experimental treatment that may be effective for some patients; the rest are managed medically (algorithm 1). (See 'Patients who have persistent pain' above.)