The algorithm starts with the two categories of patients after inguinal hernia surgery requiring medical attention: patients with pain immediately after surgery (acute pain) and patients who develop pain later during the postoperative course. This second group is also subdivided in two categories: patients who only complain in the early postoperative phase and those who have persistent pain or develop pain after some months. Acute, excruciating pain is considered an indication for early re-exploration. If postoperative pain develops later during the postoperative course, or if pain persists beyond the normal postoperative recovery period, an expectative phase of 3 months is indicated. During this time, analgesics and other conservative measures are recommended.

If pain persists after 3 months, inguinal hernia recurrence should be excluded based on physical examination. In case of clinical recurrence, operative correction is indicated, with or without triple neurectomy, depending on the type of pain (neuropathic or nociceptive). If physical examination does not demonstrate recurrence, ultrasonography is recommended as the initial diagnostic procedure to exclude occult recurrence or meshoma. If ultrasonography is unrevealing, cross-sectional imaging with MRI might detect recurrence, meshoma , or other pathologies.

If recurrence is identified and associated with pain, open anterior repair is recommended in conjunction with triple neurectomy if accompanied by neuropathic pain. From the perspective of pain management and remedial surgery for inguinodynia, if the initial hernia operation was an anterior repair (Lichtenstein, Shouldice, Bassini, McVay), laparoscopic correction does not represent the primary recommended modality because positioning of mesh in the preperitoneal space may lead to additional neuropathy (main trunk of genitofemoral nerve and preperitoneal segment of its genital branch). This is contrary to the recommendations for simple recurrence without neuropathic pain, which would favor a laparoscopic approach. If laparoscopic repair of recurrence fails to address the pain, it would not be possible to differentiate whether the source of pain is from neuropathy of nerves in front or behind the transversalis fascia. If the initial hernia operation was a posterior repair (TEP, TAP, PHS, TIPP, or other preperitoneal repair), anterior repair is recommended with open “extended” triple neurectomy, including the genitofemoral nerve trunk if needed. Laparoscopic repair for recurrence may be performed, but neuropathic pain if present must be addressed with retroperitoneal triple neurectomy proximally to the site of neuropathy.

If no anatomical pathology is identified, the surgeon should refer the patient to a pain management team familiar with CPIP. In addition to pharmacologic and behavioral treatment, interventions play a major role in the diagnosis and treatment of CPIP. Nerve blocks of the ilioinguinal, iliohypogastric and genitofemoral nerves are of significant importance, as they serve both a diagnostic and therapeutic role. If conservative or interventional modalities are unsuccessful or not durable, surgical intervention should be offered. If the original operation involves mesh in the preperitoneal space from open or laparoscopic repair, open extended triple neurectomy to resect the genitofemoral trunk or laparoscopic retroperitoneal triple neurectomy is indicated [15].

The International Association for the Study of Pain (IASP) broadly classifies postherniorrhaphy inguinodynia into nociceptive and neuropathic pain [16]. Nociceptive pain is caused by activation of nociceptors by nociceptive molecules. It is caused by tissue injury or inflammatory reaction. Neuropathic pain is caused by direct nerve injury. It is characterized by inguinodynia with radiation to the scrotum/femoral triangle, paresthesia, allodynia, hyperpathia, hyperalgesia, hyperesthesia, hypoesthesia, and positive Tinel’s sign. There is no precise demarcation between nociceptive and neuropathic pain and the complexity of diagnosis is increased by social, genetic, patient, and psychological factors.

In-depth knowledge of groin neuroanatomy is of paramount importance to prevent and treat CPIP. Knowledge of the original operative technique and detailed evaluation of the original operative report will help to determine the likely etiologies of CPIP and the nerves at risk. The diagnosis is also very much dependent on a detailed history and physical examination. Physical exam findings are dependent on the neuroanatomic course of the three inguinal nerves, their respective dermatomes, and the presence of mesh or recurrence. Tools including preoperative dermatomal mapping, quantitative sensory testing, imaging and diagnostic interventions (nerve blocks) help to characterize the etiology and direct treatment [15].

Treatment of the patient with CPIP remains a challenge and several different therapeutic strategies have been proposed. Conservative treatment with pharmacologic, topical, behavioral and expectant measures is advocated in all patients. Interventional techniques , including nerve infiltration, blockade, neuromodulation, and ablative techniques, have all been used in the management of CPIP. Results of selective or triple neurectomy of one or more of the three inguinal nerves and resection of meshoma have been published with practical efficacy. Despite this high volume of information, no consensus on the management of CPIP has been published and high-level evidence on the management of CPIP is lacking. Triple neurectomy described by Amid et al. in 1995 is currently an accepted surgical treatment for neuropathic pain refractory to conservative measures [17].

While some surgeons have had success with selective neurectomy, triple neurectomy is generally recommended due to neuroanatomic and technical considerations [15, 18]. There is significant cross-innervation between the inguinal nerves and reoperating in the scarred field becomes increasingly more difficult and morbid for subsequent remedial operations.

Extensive study of the anatomical variation of these nerves from the retroperitoneum to its terminal branches in the inguinal canal demonstrates significant variation in the number, location, and cross-innervation of these three nerves [19]. Additionally, visual identification of the nerve at the time of reoperation cannot adequately exclude injury. Electron micrography of grossly normal nerves resected at the time of triple neurectomy often demonstrates ultrastructural nerve damage. It is often challenging to identify nerves in the scarred field. Reoperation, especially with concurrent mesh removal, carries the added risk of recurrence, vascular injury, testicular compromise and visceral injury. Best available evidence suggests that triple neurectomy has higher efficacy than selective neurectomy [15].

Open or endoscopic methods are available to perform triple neurectomy, depending on the type of prior repair, the presence of recurrence or meshoma, and if orchialgia is present. Open triple neurectomy involves re-exploration through the prior operative field and is indicated when recurrence or meshoma are present or for the treatment of patients who originally underwent , anterior repair without preperitoneal placement of mesh. The ilioinguinal nerve is identified laterally to the internal ring, between the ring and the anterior superior iliac spine. The iliohypogastric nerve is identified within the anatomical cleavage between the external and internal oblique aponeurosis. The nerve is then traced proximally within the fibers of the internal oblique muscle to a point laterally to the field of the original hernia repair. Failure to do so may leave the injured intramuscular segment of the nerve behind. The inguinal segment of the genital branch of the genitofemoral nerve can be identified adjacent to the external spermatic vein between the cord and the inguinal ligament and traced proximally to the internal ring where it is severed. Alternatively, the nerve may be visualized within the internal ring through the lateral crus of the ring. Standard triple neurectomy does not address neuropathy of the preperitoneal nerves (main trunk of genitofemoral nerve and preperitoneal segment of its genital branch) after open or laparoscopic preperitoneal repair. In these cases, an “extended” triple neurectomy may be performed, dividing the floor of the inguinal canal to access the genitofemoral trunk in the retroperitoneum directly over the psoas muscle.

Nerves should be resected proximally to the field of the original hernia repair. Although there are no specific data available, ligation of the cut ends , of the nerves to avoid sprouting and neuroma formation and intramuscular insertion of the proximal cut end to keep the nerve stump away from scarring within the operative field are recommended [17]. Neurolysis, which does not address ultrastructural changes of nerve fibers, is not recommended. Simple removal of entrapping sutures or fixating devices while leaving the injured nerves behind is also not recommended and does not address irreversible damage to the nerve.

Endoscopic retroperitoneal triple neurectomy allows for access proximally to all potential sites of peripheral neuropathy, overcoming many of the limitations of open triple neurectomy after laparoscopic or open preperitoneal repair [15, 20, 21]. Prior preperitoneal laparoscopic or open procedures may damage or entrap the nerve in the preperitoneal position, rendering proximal access to the three nerves a challenge. Endoscopic access to these three nerves in the retroperitoneum allows for definitive identification of the ilioinguinal and iliohypogastric nerves at the L1 nerve root overlying the quadratus lumborum muscle and the genital and femoral branches of the genitofemoral nerve exiting from the psoas muscle. The operative technique is safe and proximal to the field of scarring from all prior inguinal hernia repairs. Complications including deafferentation hypersensitivity are a significant concern. In addition to numbness in the groin region and flank, patients undergoing proximal neurectomy may develop bulging of the lateral abdominal wall because of the additional loss of motor function of the iliohypogastric and ilioinguinal nerve (innervation of transversus abdominus and oblique muscles). In the absence of recurrence or meshoma, endoscopic management may be the preferred technique for definitive operative management of CPIP. Selection of appropriate patients is most important and management is best deferred to experienced hernia specialists.