2. Diagnostic approach <strong>of</strong> postherniorrhaphy <strong>inguinal</strong> <strong>pain</strong>Several tools for <strong>pain</strong> measurement in <strong>chronic</strong> postherniorrhaphy <strong>syndromes</strong> are currentlyused. Multi-dimensional <strong>pain</strong> tools including the McGill Pain questionnaire andWisconsin Brief Pain questionnaire measure sensory, affective and evaluative aspects <strong>of</strong><strong>pain</strong> 18,19 . Visual Analogue Scale (VAS) and a Verbal Rating Scale (VRS) are two frequentlyused unidimensional scales assessing sensory aspects (e.g. <strong>pain</strong> intensity). Choosing a<strong>pain</strong> measurement tool and its interpretation can greatly affect outcome results. Inchapter 4 two <strong>pain</strong> tools, the Visual Analogue Scale (VAS) and 4-point Verbal RatingScale (VRS), are analyzed for scale failure, sensitivity and interpretability. A questionnaireidentified <strong>pain</strong> intensity level in a cohort <strong>of</strong> patients that previously underwent<strong>inguinal</strong> herniorrhaphy. Current <strong>pain</strong> intensity was graded on a 4 point-VRS-scale (no<strong>pain</strong>, mild, moderate or severe <strong>pain</strong>) and on a 100 mm-VAS-scale (0=no <strong>pain</strong>, 100=unbearable). ‘Scale failure’ (one or both tests not completed correctly) was determined,and cut-<strong>of</strong>f points for the VAS test were calculated by creating the optimal Kappa coefficientbetween both tools. The response rate was 78.2%. Scale failure was observed fivetimes more frequently in VAS tests compared to VRS. Advanced age was a significantrisk factor for scale failure. The four categories <strong>of</strong> VRS corresponded with mean VASscores <strong>of</strong> 1, 20, 42 and 78 mm, respectively. VAS categories associated with the highestKappa coefficient (k = 0.78) were: 0-8 = no <strong>pain</strong>, 9-32 = mild, 33-71 = moderate, >71 =severe <strong>pain</strong>. VAS scores grouped per VRS category showed considerable overlap. However,age and sex did not significantly influence cut-<strong>of</strong>f points. These results clearly indicatethat the VRS should be favoured over the VAS in postherniorrhaphy <strong>pain</strong> assessment.Although an unidimensional <strong>pain</strong> tool is easy and highly accessible, multidimensionalmeasurement tools may provide more reliable information. Recently, a validated <strong>inguinal</strong><strong>pain</strong> questionnaire (IPQ) was published 21 . A seven step fixed-point rating scale wasused to assess <strong>pain</strong> with steps linked to <strong>pain</strong> behaviour. Current and worst <strong>pain</strong> duringthe previous week is measured. A second part <strong>of</strong> the questionnaire focuses on interferencewith daily activities. Such a novel multidimensional <strong>pain</strong> questionnaire may bepreferable over unidimensional <strong>pain</strong> scales, but comparisons are currently unavailable.3. A novel classification <strong>of</strong> <strong>chronic</strong> postherniorrhaphy <strong>pain</strong>In the late eighties, neuropathic <strong>pain</strong> was highlighted as a phenomenon by Lichtensteinproviding a description <strong>of</strong> the <strong>inguinal</strong> neuro-anatomy as well as a clinical differentiationbetween genit<strong>of</strong>emoral and ilio<strong>inguinal</strong> neuralgia 21 . Eight years later,Cunningham published an alternative classification on <strong>chronic</strong> <strong>pain</strong> after <strong>inguinal</strong>hernia repair 22 . Three different <strong>pain</strong> <strong>syndromes</strong> based on clinical investigation <strong>of</strong> tenpatients were proposed: nociceptive, neuropathic and visceral. According to his judgement,most patients suffer from nociceptive <strong>pain</strong> due to suture damage <strong>of</strong> the periosteumand the <strong>inguinal</strong> ligament. In contrast, only ten percent (n=1) suffered from neuropathic<strong>pain</strong> caused by nerve damage. Visceral <strong>pain</strong> defined as <strong>pain</strong> during ejaculation was seenin another ten percent (n=1). In 2004, a classification was introduced that differentiatedbetween neuropathic (nerve compression or neuroma formation), non-neuropathic(periosteal reaction, scar tissue, mechanical pressure <strong>of</strong> folded mesh) or a mixed form 23 .In Chapter 5 a novel classification <strong>of</strong> <strong>chronic</strong> postherniorrhaphy <strong>pain</strong> <strong>syndromes</strong> is proposedbased on an extensive survey in more than two thousand patients. All patientswith an elective <strong>inguinal</strong> hernia repair performed over a 5 year period received a questionnaireevaluating <strong>chronic</strong> <strong>inguinal</strong> <strong>pain</strong> as described in chapter 2 (n=2164). Patientswith moderate to severe <strong>pain</strong> complaints (VAS ≥3) were invited for an interview and anoutpatient department physical examination. Moderate to severe <strong>pain</strong> was present in211 patients (11.9 per cent). Three separate groups <strong>of</strong> diagnoses were identified basedon a follow-up study in 148 patients. Group I: neuropathic <strong>pain</strong> (n=72, 47%) indicating<strong>inguinal</strong> nerve damage, Group II: non-neuropathic <strong>pain</strong> (n=40, 27%) due to variousdiagnoses including periostitis (n=18) and recurrent hernia (n=13), and Group III: a tenderspermatic cord and/or a tight feeling in the lower abdomen (termed ‘funiculodynia’,n=43, 28%). Chronic <strong>pain</strong> following elective hernia repair is diverse in etiology but aclassification may contribute to the development <strong>of</strong> tailored treatment regimens. Ourclassification may share similarities with Amid’s 23 . However, we identified a large separategroup <strong>of</strong> patients presenting with diffuse funicular <strong>pain</strong> without neuropathic <strong>pain</strong>symptoms. It is our hypothesis that compression by scar tissue, venous congestion or<strong>chronic</strong> inflammation as a reaction to mesh placement may act as possible underlyingcauses in this subpopulation. A recent case report describes an ilio<strong>inguinal</strong> nerve meshentrapment with neurophysiological changes that suggests an inflammatory cause forthis <strong>chronic</strong> <strong>pain</strong> syndrome 24 . Future research may aim at identifying the central role <strong>of</strong>funicular structures in <strong>inguinal</strong> <strong>pain</strong> <strong>syndromes</strong>.4. <strong>Surgical</strong> <strong>management</strong> <strong>of</strong> <strong>chronic</strong> <strong>inguinal</strong> <strong>pain</strong> <strong>syndromes</strong>Conservative treatment including nerve blocks, analgesics or transcutaneous electricnerve stimulation (TENS) is <strong>of</strong>ten unsuccessful. Selective neurectomy may be efficientbut long-term results are scarce. We assessed the long-term efficacy <strong>of</strong> surgical neurectomyfor <strong>chronic</strong> postherniorrhaphy groin neuralgia (chapter 6). A population <strong>of</strong> postherniorrhaphygroin <strong>pain</strong> patients treated by neurectomy received a questionnaireevaluating current <strong>pain</strong> intensity, overall treatment results, and effects on sexual intercourse-related<strong>pain</strong> symptomatology. Risk factors for failure and a learning curve wereinvestigated. Fifty-four patients underwent a neurectomy over a 5-year time period, andforty-nine patients responded to the questionnaire (response rate 91%). After a medianfollow-up period <strong>of</strong> 1.5 years, about half <strong>of</strong> the patients (52%) claimed to be <strong>pain</strong>free oralmost <strong>pain</strong> free, a quarter (24%) experienced some <strong>pain</strong> reduction but still experienced<strong>pain</strong> at a regular basis, whereas the remaining quarter (24%) did not benefit from theneurectomy at all. Sexual intercourse-related <strong>pain</strong> responded favourably to neurectomyin two-thirds <strong>of</strong> the involved patients.140 Chapter 10Summarizing discussion, conclusions, and future perspectives 141
Results <strong>of</strong> our study are in concert with previous reports. In general, approximately threequarters <strong>of</strong> the patients will benefit from a neurectomy. Unfortunately, one fourth continuesto suffer from severe <strong>pain</strong>. If one studies the literature, reasons for treatmentfailure are unclear. Several factors may be important. First <strong>of</strong> all, appropriate patientselection is crucial. Patients with peripheral nerve injury may develop sensitization <strong>of</strong> thecentral nervous system over time. As a rule these patients are refractory to surgicalperipheral nerve interventions but should be treated with <strong>pain</strong> medication. Second, anadequate surgical technique is <strong>of</strong> great importance. The affected nerve needs to beidentified in a scarred operative field and resected as far proximal and distal as possibleburying the nerve ends in healthy muscular tissue. To prevent neuroma formation inunaffected neurectomized nerve ends, we believe that only the affected nerve(s) shouldbe removed, ‘the tailored approach’. A learning curve is present and failures significantlydepended on previously received <strong>pain</strong> treatment.A surgical neurectomy provides good long-term <strong>pain</strong> relief for postherniorrhaphy groinneuralgia in the majority <strong>of</strong> patients. Hernia surgeons should take their responsibilityfor this iatrogenic complication and incorporate selective neurectomy in their surgicalarmamentarium. Future research should focus on identifying additional factors associatedwith unfavourable surgical outcome.As high level evidence based treatment regimes for iatrogenic <strong>inguinal</strong> <strong>pain</strong> <strong>syndromes</strong>are currently lacking, patients usually receive a random combination <strong>of</strong> <strong>pain</strong> medication,local nerve blocks or an occasional surgical neurectomy. A randomized controlled trial('GroinPain Trial') was constructed to identify the optimal treatment modality in thispopulation. In chapter 7 aim and rationale <strong>of</strong> this trial are presented. Adult patientswith <strong>chronic</strong> postherniorrhaphy <strong>inguinal</strong> <strong>pain</strong> (> 3 months) caused by <strong>inguinal</strong> nerveentrapment with a temporary but significant <strong>pain</strong> reduction after a lidocain nerve blockare eligible for randomization. They either receive repetitive nerve blocks with lidocain,corticosteroids and hyaluronic acid, or a 'tailored' surgical neurectomy. Patient enrollmentstarted in February 2006 and is expected to end in June 2011. Initial results will beavailable towards the end <strong>of</strong> 2011. This trial is the first randomized controlled effortcomparing two invasive treatment modalities for peripheral <strong>inguinal</strong> nerve entrapment.As awareness and knowledge on <strong>chronic</strong> neuropathic <strong>pain</strong> after <strong>inguinal</strong> herniorrhaphyin the near future is expected to increase, findings <strong>of</strong> this trial will aid in optimizingcare for this patient population.Pfannenstiel incisions are also incidentally associated with <strong>chronic</strong> lower abdominal<strong>pain</strong> due to nerve entrapment (2-4%) 2 . Treatment options include peripheral nerve blocksor a neurectomy <strong>of</strong> neighbouring nerves. Knowledge on adequate (surgical) <strong>management</strong>is limited. In chapter 8 we assessed long-term <strong>pain</strong> relief after local nerve blocksor neurectomy in patients suffering from <strong>chronic</strong> <strong>pain</strong> due to Pfannenstiel-inducednerve entrapment. Patients treated for iliohypogastric and/ or ilio<strong>inguinal</strong> neuralgiafollowing a Pfannenstiel incision received a questionnaire assessing current <strong>pain</strong> intensity(by 5-point Verbal Rating Scale), complications and overall satisfaction. Twenty-sevenwomen with Pfannenstiel-related neuralgia were identified over a seven-year period.A single diagnostic nerve block provided long-term <strong>pain</strong> relief in 5 patients. This phenomenonmay be explained by resetting the <strong>pain</strong> threshold to normal levels. A similareffect is occasionally observed in postherniorrhaphy groin neuralgia. Satisfaction in theremaining women undergoing neurectomy (n=22) was good to excellent in 73%,moderate in 14%, and poor in 13%. Smaller series show similar success rates 25,26 . Interestingly,successful treatment improved sexual intercourse-related <strong>pain</strong> in most females,a phenomenon that has never been described before in literature. Co-morbidities (endometriosis,lumbosacral radicular syndrome) and earlier <strong>pain</strong> treatment were identifiedas risk factors for surgical failure. Some cases <strong>of</strong> treatment failure may also beexplained from the concept <strong>of</strong> genetic susceptibility for <strong>chronic</strong> <strong>pain</strong> syndrome developmentas described in postherniorrhaphy groin <strong>pain</strong> as well 7 . This study demonstratesthat peripheral nerve blocking provides long-term <strong>pain</strong> reduction in some individualswith post-Pfannenstiel neuralgia. An iliohypogastric or ilio<strong>inguinal</strong> nerve neurectomyis a safe and effective procedure in most remaining patients. Gynaecologists must beprepared to <strong>of</strong>fer a surgical consultation to this group <strong>of</strong> patients.5. Occupational disability after <strong>inguinal</strong> hernia repairResumption <strong>of</strong> daily leisure activities and occupational obligations is considered animportant outcome measure after hernia repair. However, the exact percentage <strong>of</strong> <strong>pain</strong>patients confronted with occupational disability is unknown. In chapter 9 the effect <strong>of</strong>operative and non-operative treatment on resolving occupational disability due to postherniorrhaphy<strong>inguinal</strong> neuralgia is evaluated.All relevant studies on treatment for postherniorrhaphy <strong>inguinal</strong> neuralgia were reviewedwith respect to effect on occupational disability. A recently published registry <strong>of</strong>patients with postherniorrhaphy neuralgia treated by neurectomy was analyzed foroccupational disability. Patients were contacted by telephone and given a set <strong>of</strong> predeterminedquestions concerning pre- and postoperative disability. Finally, a cost-benefitanalysis was made.Only 4 out <strong>of</strong> 23 studies on neurectomy for <strong>inguinal</strong> neuralgia reported on occupationaldisability as an outcome measure. These few studies demonstrated that some 56 to 100%<strong>of</strong> the patients could resume their occupational obligations after <strong>pain</strong> treatment. Studieson non-operative <strong>pain</strong> treatment and occupational disability appeared unavailable.Forty-eight patients previously treated by neurectomy were analyzed for occupationaldisability. Severe <strong>pain</strong> disabled 13 patients and a neurectomy resulted in total recoveryin 7 (7/13, 54%). An estimating cost-benefit analysis showed that effective <strong>pain</strong> treatmentsuch as a tailored neurectomy can save a minimum <strong>of</strong> € 1.8 million <strong>of</strong> workers’ com-142 Chapter 10143