Classifying Postherniorrhaphy Pain Syndromes Following Elective Inguinal Hernia Repair

The issue of unraveling the dilemma of long-term moderate to severe postherniorrhaphy pain is not new [10]. However, to our knowledge this is the first study in which a large cohort of patients was examined at the outpatient department to clarify the underlying mechanisms responsible for pain following hernia repair. A similar but smaller study was conducted by Cunningham et al. in 1996 [8]. In that study a subset of 10 patients referred to a pain clinic with persisting pain was investigated 2 years after inguinal repair. The authors proposed three distinct pain syndromes; somatic (n = 9), neuropathic (n = 1), and visceral (n = 1). The first one was judged as a ligamentous pain syndrome caused by suture insertion in the iliopubic tract and periosteum. The second syndrome was neuralgic and caused by inguinal sensory nerve damage, whereas a third complex was associated with ejaculation pain. They concluded that severe pain syndromes following hernia repair are most commonly somatic in origin. Similar groups of patients were identified in the present study. Pain of neuropathic origin was suspected in nearly half of the patients and was confirmed by nerve block in 28% of all patients. If one extrapolates these results to the initial patient population encompassing 1,766 individuals, one could cautiously assume that at least 4% of all corrected inguinal hernias are associated with nerve entrapment or damage. Previous authors have estimated a similar prevalence, varying between 3% and 5% [11]. Chronic nerve irritation should be considered an important cause of moderate or severe chronic pain after inguinal hernioplasty.

Another well-known source of postherniorrhaphy pain is periostitis of the pubic tubercle [12]. A too deeply positioned suture aimed at medially affixing the mesh may cause inflammation and chronic irritation. In the examined cohort, one in every eight patients experienced pain while exerting digital pressure on the pubic tubercle. This pain syndrome can be avoided by careful placement of suture material by the surgeon, ideally sparing the bone’s periosteal layers. An injection with a local anesthetic and corticosteroids in painful periosteum can be tried as the first line of treatment, as this was effective in a substantial number of our patients. Surgical suture removal must be considered if pain persists.

When a patient presents with residual pain following hernial repair, a recurrent hernia is often the only diagnosis that surgeons consider and rule out. Although relatively infrequent in the present study, 13 patients did have such a recurrence. This number approximates the 1% of the initial 1,766 patients used in our previous questionnaire study. The recurrence rate is probably higher because asymptomatic and mildly symptomatic recurrences remain undetected.

A variety of additional musculoskeletal problems were observed in the remainder of the patients with recurrent pain, including iliopectineal bursitis, adductor tendinitis, and referred low back pain. These pain syndromes are very likely the secondary result of postural and functional changes in the presence of persisting inguinal pain. However, a third group of 43 individuals demonstrated a clearly distinct history and physical examination. They presented with a tender spermatic cord (after open mesh repair) or a tight aching feeling in the lower abdomen (after laparoscopic procedures). Compression by scar tissue or prosthetic material may explain this type of groin pain [9]. Compromised musculotendinous structures might play a roll as well. It remains unclear if venous congestion contributes to pain in this group of patients. Overall pain intensity is less pronounced than that reported by the neuropathic pain group, although most patients experienced some limitation in daily activities. Except for pain medication, no treatment was available for them. We suggest naming this type of pain “funiculodynia,” as this syndrome is mainly characterized by pain in structures surrounding the spermatic cord.

Prevalence, etiology, and treatment of genital complications following hernia repair including erectile and ejaculatory pain are largely unknown. In a recently published Danish questionnaire study 3% of younger male patients with inguinal hernia repair exhibited pain during sexual activity and subsequent sexual dysfunction [13]. In the present study dysejaculation was reported by one of every five male patients. Several pathophysiological mechanisms have been suggested, among them intraoperative nerve damage, dysfunction of periurethral structures involved in ejaculation, or encasement of the spermatic cord caused by scar tissue. This is supported by anecdotal reports on patients with dysejaculation in which dissection of twisted fibrotic spermatic cords combined with an ilioinguinal neurectomy provided total pain relief [14]. Because of the high incidence of such complaints and the sparse literature, more research on the etiology and treatment of dysejaculatory conditions after inguinal hernioplasty is definitely warranted.

Over 30% of all patients reported suffering from other chronic pain syndromes as well. A correlation between the onset of postherniorrhaphy pain and other pain syndromes has been described in the hernia literature, and it may be due to genetic and psychosocial factors [13]. Patients with a tendency to develop chronic pain are more susceptible to develop additional pain syndromes.

Classifying postherniorrhaphy pain syndromes may allow for tailored treatment regimens. The first step in a protocol for treatment of postherniorrhaphy neuralgia, described by Lichtenstein nearly two decades ago, consisted of primary diagnosis and treatment by injections [10]. Surprisingly, in the present study a single diagnostic nerve block with lidocaine led to long-term (> 1 month) pain reduction in 25% of our patients, confirming the therapeutic potential of such injections. Although it is known to occur, the phenomenon of permanent or long-term cure following injection of short acting anesthetics is not well understood [15]. If (repeated) injection therapy fails, the second step might be operative transsection [10]. After early reports, it was suggested by Amid that transsection should include all three groin nerves, and the procedure was named “triple neurectomy” [9]. Because of central and peripheral communication and possible involvement of all three nerves, a maximal length of ilioinguinal, iliohypogastric, and genitofemoral in both directions should be transsected and removed.

Reports on the effect of the mesh on nerves and chronic pain in hernia repair are scarce. According to a recent animal study, inserted mesh may lead to an inflammatory and fibroblastic response resulting in adhesions and mechanical entrapment of adjacent nerve fibers and structures such as the spermatic cord [16]. Whether these mesh-related nerve changes are responsible for any pain sensation is unknown. One study comparing mesh with suturing techniques using the body’s own tissue showed similar rates of chronic pain [17]. Nevertheless, removal of mesh in combination with neurectomy appeared to be successful in 60% of patients with chronic inguinodynia [18]. Apart from its inflammatory potential, implanted mesh may also exert mechanical pressure on neighboring structures or may fold or wrinkle (“meshoma”), causing chronic pain [19]. A (partial) removal of mesh in combination with a (triple) neurectomy may be considered the preferred treatment in patients with severe neuropathic pain in the presence of a meshoma. In concert with a recent review on surgical management of chronic pain after groin hernia repair, there is an obvious need for more prospective research [20].

The results of the present study demonstrate that the differential diagnosis of moderate or severe postherniorrhaphy pain is diverse, but the findings allow for symptom classification with resultant treatment options. Proper research concerning different types of therapy for chronic pain after groin hernia repair is warranted. A randomized controlled trial comparing peripheral injections with neurectomy has recently been initiated by our group of investigators.