Chronic pain following inguinal hernia repair is quite common and may reduce quality of life. Determining the etiology of this multifaceted condition can be challenging.

The response of a patient to hernia repair is affected by their pre- and post-operative physical and psycho- social state. Clinical and technical aspects of the surgical operation may also play a major role in short- and long-term outcomes.
Post-hernia repair pain is considered to be either
“non-neuropathic” (resulting from scar tissue or mechanical pressure) or
“neuropathic” (resulting from nerve injury or compression) or
combination of both.
Neuropathic pain is reported to be more prevalent.

PREVALENCE OF CHRONIC PAIN AFTER HERNIA REPAIR
A 2012 Cochrane review by Willaert et al. reports the risk for post-hernia repair chronic pain to range from 7.83% to 40.47% and 2 to 4% of reported post-herniorrhaphy chronic pain is serious enough to affect patient’s daily activities. The incidence of debilitating pain is estimated to be 0.5 to 6% by an international group of experts.

POTENTIAL PREDICTORS OF CHRONIC PAIN POST HERNIA REPAIR
Patient factors

Technical factors

The Role of Nerve Preservation
familiarity with the normal and variant anatomy of the nerves is fundamental in all techniques of hernia repair.
Careful dissection that respects tissue planes and critical structures may result in less postoperative morbidity. Many surgeons favor meticulous dissection and nerve preservation in inguinal hernia repair, including the ilioinguinal, iliohypogastric, genitofemoral, femoral and lateral femoral cutaneous nerves.
However, the proximity of suture material or mesh as well as tension on these nerves in nonmesh repairs has been implicated in the pathogenesis of chronic postoperative pain. To avoid this problem, some surgeons advocate routine division of the ilioinguinal, iliohypogastric and genital branch of genitofemoral nerves. The rationale for this approach is that numbness is preferable to chronic pain. routineneurectomy derives no significant benefit over selective preservation.
For practice assessment, identification and intraoperative management of the nerves encountered in the operative field should be documented. This may be helpful in evaluating and treating subsequent pain symptoms.

Mesh or No Mesh
The superiority of tension-free hernia repair using prosthetic mesh in preventing recurrent hernia is widely accepted.
Various techniques differ in the mesh placement site, configuration and composition and the need for sutures to secure the prosthesis to the surrounding tissue.

Compared with traditional non-mesh repairs, tension-free techniques offer theoretical advantages of less dissection and injury due to entrapment or tension on adjacent nerves. On the other hand, the mesh constitutes a relatively large foreign body that may induce significant inflammation that can produce pain, feelings of fullness and discomfort. A meta-analysis has suggested that these pain syndromes may be related to the weight, stiffness and composition of the prosthetic material (Am J Surg 2007;194:394-400).

Open vs. Laparoscopic
Chronic pain following intra- or preperitoneal laparoscopic techniques has been linked to the injury of inguinal nerves that often are not encountered in open anterior repairs. These include the lateral femoral cutaneous nerve, femoral branches of the genitofemoral nerve and the femoral nerve itself (SurgClin North Am 2008;88:203-215).
CAUSES OF CHRONIC PAIN AFTER HERNIA REPAIR
Meshomas
Meshomas are the result of complications that occur with the use of prosthetic meshes during hernia surgery.
Scar tissue
Scar tissue or tissue damage resulting from hernia surgery can also cause pain.
Nerve damage
At the time of hernia surgery, nerve damage can occur as a result of nerves getting trapped in sutures or mesh. Benign tumors, also known as neuromas or nerve tumors, can develop after the surgery is done. A neuroma is characterized by swelling of the nerve and is caused by trauma or compression. The swelling in the nerve can cause permanent nerve damage, resulting in pain and discomfort. The nerves innervating the groin area include the ilioinguinal nerve, iliohypogastric nerve and genitofemoral nerve. The lateral femoral cutaneous nerve could also be injured.
MANAGEMENT OF CHRONIC PAIN AFTER HERNIA SURGERY
Multidisciplinary non-interventional pain management
Chronic pain is complex in nature. It is not only a product of neuropathic pain and nociceptive components but is also influenced and modulated by emotional, cognitive, social, and genetic factors. Neuropathic pain is difficult to treat, and the pain is complicated by central sensitization and psychological comorbidities. A multimodal, multidisciplinary treatment approach is therefore necessary.
Non-pharmacological treatments

Physiotherapy, TENS machine, acupuncture and mind–body therapies provide ways of ameliorating pain conditions and are important cornerstones in a multimodal approach.

Pharmacological treatments
Anti neuropathic drugs are likely to be the main stay of management in chronic post surgical pain. Opioids are second-line treatment alternatives but long-term use of opioids should be discouraged.
INTERVENTIONAL TREATMENTS
Ilioinguinal, Iliohypogastric and Genitofemoral nerve blocks
Nerve blocks of the Ilioinguinal, Iliohypogastric and Genitofemoral nerves have been used for both diagnostic and therapeutic purposes in the diagnosis and treatment of chronic post hernia surgery pain.

Pulsed radiofrequency ablation of inguinal nerves If nerve blocks have been performed and provided significant analgesia but did not provide long-term relief, neuroablative techniques such as chemical neurolysis, cryoablation, and pulsed radiofrequency (PRFL) ablation may be considered for longer-lasting effect.

Pulsed radiofrequency treatment of ilioinguinal nerve, iliohypogastric nerve and genito femoral nerve under real time ultrasound guidance can provide long term pain relief in patients with chronic groin pain after inguinal hernia surgery.

Dorsal root ganglion pulsed radiofrequency
In refractory cases, nerve root blocks at T12, L1 and L2 levels can be offered, followed by pulsed radiofrequency treatment targeting the dorsal root ganglions at these levels. This can provide sustained pain relief in some cases.

Neuromodulation
Neuromodulation techniques, either peripheral nerve field stimulation (PNFS) or spinal cord stimulation (SCS), may be considered for use in a select group of patients when all other conventional treatments have failed. Surgical Management. (pain management by surgery)