Approximately 96% of all groin hernias are inguinal hernias, with the remaining 4% being femoral. Hernias are bilateral in 20% of cases. The most common abdominal wall hernia is an inguinal hernia with a male to female preponderance of 9 to 1. Femoral hernias are more common in women.
Chronic pain after hernia surgery is not uncommon and can result in debilitating pain in some patients. Conservative management can be considered including anti neuropathic medications but in some patients injection treatments may be needed to help break the pain cycle. The ilioinguinal nerve can be targeted under ultrasound guidance and nerve ablation techniques may be considered in patients who fail to make progress with conservative management.
At Pain Spa Dr. Krishna is very experienced in performing nerve blocks under real time ultrasound guidance, using state of the art equipment. This ensures 100% accuracy and our complication rates are extremely low. Dr Krishna is very experienced in pulsed radiofrequency treatments and has successfully treated several patients with chronic post hernia surgery pain.
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 a combination of both. Neuropathic pain is reported to be more prevalent. Kalliomaki et al state that as measured by various quality of life scales, “persistent post-herniorrhaphy pain is mainly neuropathic and has a substantial impact on health- related quality of life.”
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.
Given the frequency of hernia repair operations performed worldwide (annually, 2800 per million in the US and Europe), a considerable number of patients are affected by this disabling chronic pain.
In most series, neuropathic pain is the most common etiology of chronic postoperative pain. Thus, 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.
Several series have analyzed postoperative pain syndromes in inguinal hernia repairs in which the nerves have been preserved or selectively divided, and many of them have concluded that routine neurectomy derives no significant benefit over selective preservation (Hernia 2007;11:243-246). However, a randomized controlled trial found significantly decreased chronic groin pain in a prophylactic neurectomy group six months after Lichtenstein repair (Ann Surg 2006;224:27-33).
Lack of consensus likely relates to the heterogeneity of surgeons’ techniques, including type of repair and mesh selection. Despite the controversy, selective neurectomy in the setting of potential entrapment or excess neural tension may be a reasonable approach. 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.
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. As a consequence, relationships between prosthetic mesh and post-herniorrhaphy pain are not well defined.
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).
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 (Surg Clin North Am 2008;88:203-215).
The desire to decrease these complications has led to technical refinements that require more precise mesh placement or avoid the use of tacking staples to secure prosthetic mesh, but their effectiveness remains unclear. The evidence in the literature has yet to demonstrate any significant differences between open and laparoscopic repairs, suggesting that the inflammatory response to the mesh itself may be a more significant factor.
Meshomas are the result of complications that occur with the use of prosthetic meshes during hernia surgery. Although prosthetic meshes have been instrumental in lowering the recurrence of an inguinal hernia after hernia repair, they cause certain complications. Depending on the surgeon’s method of procedure, the mesh may be implanted in front of or behind the transversalis fascia without fixation or may be fixed in place with tissue adhesive, staples or tacks. According to the American Medical Association, lack of fixation, improper fixation or lack of dissection, leaving little to no room for the prosthesis, is a problem. This can cause the mesh to fold and wrinkle up until it becomes a wadded-up ball.
Scar tissue or tissue damage resulting from hernia surgery can also cause pain. Scar tissue can result from injury, repetitive motion or surgery. It’s characterized by fibrotic tissue that dies and forms in mostly joints, ligaments, tendons, muscles and fascia. When tissue damage happens, a healing process begins to take place. Inflammation occurs for the first few days. Then the damaged tissue heals with scar tissue formation rather than forming brand new tissue. According to ScarTissueTherapy.com, research shows that scar tissue is weak, less malleable and subject to re-injury, with 1,000 times more sensitivity to pain than tissue that is healthy. This results in chronic pain that can be persistent for a number of years.
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.
These include osteitis pubis, visceral pain and recurrence of hernia.
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.
The perception of pain depends on multiple factors such as experience, fears, context, and meaning and can be modulated through cognition and emotion. Physiotherapy, TENS machine, acupuncture and mind–body therapies provide ways of ameliorating pain conditions and are important cornerstones in a multimodal approach.
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.
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. Historically, these nerve blocks were performed using a blind technique, using anatomic landmarks as guidance for needle placement.
Recent advances in ultrasound technology and its use in regional anesthesia have enabled practitioners to perform these blocks under a direct visualization, with successful outcomes reducing risk of intraperitoneal needle placement and allowing for a smaller volume of injectate due to improved accuracy.
In a recent report by Thomassen et al the authors found ultrasound-guided nerve blocks to be effective in treating of chronic post hernia surgery pain with successful prolonged pain relief after a median follow-up time of 20 months.
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.
The use of pulsed radiofrequency ablation in the treatment of chronic post hernia repair pain has been reported in multiple case series as well as in a recent systematic review. PRF ablation delivers high intensity currents in pulses, which allows for heat (typically 42°C) to dissipate during the latent phase so that neurodestructive temperatures are not obtained, thus lowering the risk of neuroma formation, neuritis-type reaction, and deafferentation pain. This mild heating of the nerve tissue is thought to temporarily block nerve conduction; however, the exact mechanism by which PRF ablation provides analgesia is unclear.
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.
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 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.
While the majority of patients with chronic post surgical pain can be managed with pharmacologic, interventional, and behavioral measures, those refractory to a systematic regimen of diagnostic and interventional measures may be considered for operative remediation. Successful outcomes, however, are entirely dependent upon choosing patients with discrete, neuroanatomic problems that may be corrected with surgery. Failure of conservative measures, in and of itself, is not an indication for further surgery.