Surgical management of chronic inguinal pain syndromes - Liespijn

INTRODUCTIONChronic pain following elective inguinal hernia repair is common. Approximately 14 to54 per cent of patients still experience some degree of inguinal pain several years after‘successful’ surgery 1-6 . Moreover, up to 21 per cent of patients is functionally impaired inwork or leisure activities 1,2 . One per cent of individuals suffering from pain after openrepair is eventually referred to a specialized pain clinic, as is 0.4 per cent after laparoscopichernia repair 7 .Efforts have been made to clarify the etiology of these postoperative pain syndromesusing pain descriptors in questionnaires 2,3 . Neuropathic symptomatology was moreoften present compared to non-neuropathic descriptors suggesting a significant nerverelatedcontribution to pain. However, this approach only allows for a limited insight inunderlying etiology. A complete physical examination possibly supported by additionaltesting may provide answers in the quest for a correct diagnosis and tailored treatmentregimens.Aims of the present study were to classify postherniorrhaphy pain syndromes followingelective inguinal hernia repair.DEFINITIONSSome authors have attempted to classify inguinal pain after hernia repair 8,12 . In thepresent study it was decided to make a distinction between neuropathic and non-neuropathic(nociceptive) causes of pain as suggested by Amid 12 .Neuropathic pain is characterized as an activity-induced sharp pain, located in proximityto the inguinal scar. The pain frequently radiates towards scrotum, labium and/orupper inner thigh. Upper body stretching or twisting and/or hip joint flexing may causepain due to nerve traction or compression. Physical examination often reveals signs ofa disturbed neurophysiologic equilibrium including hypoesthesia, hyperesthesia orallodynia. A distinct trigger point situated in or close to the scar may cause painfollowing stimulation, e.g. after palpation. A local anaesthetic nerve block can possiblyact as a diagnostic and (temporary) therapeutic agent. The complex of symptomatologyis thought to be caused by an entrapment of ilioinguinal, iliohypogastric or genitalbranches of the genitofemoral nerves. Suture material, staples or tacks, perineuralfibrosis or prosthetic material are all implicated as well as accidental iatrogenic nervedamage possibly causing a neuroma.In non-neuropathic causes of inguinal pain after hernia repair, other conditions areresponsible for symptomatology including residual/ recurrent hernias, hip pathology,periostitis pubis, etc. All nerves are usually intact. These definitions are applicable in thefollowing text.PATIENTS AND METHODSThe study was conducted in the Máxima Medical Center, a teaching hospital servingapproximately 350,000 inhabitants in the Eindhoven and Veldhoven region, TheNetherlands. Patients were eligible for study if they reported moderate or severe pain(Visual Analogue Scale, VAS ≥ 3, range 0 = no pain, 10 = unbearable pain) as identifiedby a recent questionnaire study (figure 1) 1 .Eligible patients were contacted and invited at the Surgical Outpatient Department fora standardised interview and physical examination. Current pain intensity was thenagain tested using a VAS-score. Patients received a local injection of 10 cc lidocainhydrochlorid1% (Lidocain®) if the combination of patient’s history and physical examination(trigger point) suggested pain of neuropathic origin. If a non-neuropathic originof pain was suspected, the diagnostic approach depended on the suggested diagnosis.For instance, if a periostitis was diagnosed, patients received a local injection containing5 cc lidocain and 40 mg methylprednisolonacetaat 40 mg/ml (depo-medrol® = corticosteroid)at the site of maximal pain intensity. Additional imaging techniques includingultrasound, CT-scans, or Magnetic Resonance Imaging were performed if deemednecessary. Following a 10 minute equilibrium period after injection, this regimen’sefficacy was evaluated using a VAS score.RESULTSDemographic and pain characteristicsFigure 1 describes patient inclusion. A total of 211 patients (11.9 per cent) was eligible forstudy as dictated by a VAS-score ≥ 3. Sixty-three patients did not visit the outpatientdepartment for reasons stated in figure 1, leaving 148 patients (8.4 per cent) for analysis.The mean age of participants was forty years, with the majority being male (87.2 percent, table 1). Most hernia operations were done by open techniques (76.4 per cent,mainly Lichtenstein) whereas almost one quarter of patients (23.6 per cent) was treatedusing a laparoscopic method (TEP 12.8 per cent, TAPP 10.8 per cent).Pain history of the study population is listed in Table 2. Almost 90 per cent reportedgroin pain prior to corrective surgery. However, the present postoperative pain level wasjudged comparable or worse by half of the patients. Nearly always the pain had starteddirectly after surgery, and its severity was considered by 28 patients (18.9 per cent) to beprogressive. More than half of the individuals was constantly suffering from pain. Otherchronic pain syndromes (chronic headache, low back pain etc) were observed in 31.8 percent of patients.66 Chapter 5Classifying postherniorrhaphy pain syndromes following elective groin hernia repair 67