Somatosensory Outcomes Following Re-Surgery in Persistent Severe Pain After Groin Hernia Repair: A Prospective Observational Study.

Purpose: After groin hernia repair (globally more than 20 million/year) 2-4% will develop persistent severe pain (PSPG). Pain management is challenging and may require multimodal interventions, including re-surgery. Quantitative somatosensory testing (QST) is an investigational psychophysiological tool with the potential to uncover the pathophysiological mechanisms behind the pain, ie, revealing neuropathic or inflammatory components. The primary objective was to examine and describe the underlying pathophysiological changes in the groin areas by QST before and after re-surgery with mesh removal and selective neurectomy. Patients and Methods: Sixty patients with PSPG scheduled for re-surgery and with an inflammatory "component" indicated by blunt pressure algometry were examined in median (95% CI) 7.9 (5.8-11.5) months before and 4.0 (3.5-4.6) months after re-surgery. The QST-analyses included standardized assessments of cutaneous mechanical/thermal detection and pain thresholds. Suprathreshold heat stimuli were applied. Deep tissue sensitivity was tested by pressure algometry. Testing sites were the groin areas and the lower arm. Before/after QST data were z-transformed. Results: Re-surgery resulted in median changes in rest, average, and maximal pain intensity scores of -2.0, -2.5, and -2.0 NRS (0/10) units, respectively (P = 0.0001), and proportional increases in various standardized functional scores (P = 0.0001). Compared with the control sites, the cutaneous somatosensory detection thresholds of the painful groin were increased before re-surgery and increased further after re-surgery (median difference: 1.28 z-values; P = 0.001), indicating a successive post-surgical loss of nerve fiber function ("deafferentation"). Pressure algometry thresholds increased after re-surgery (median difference: 0.30 z-values; P = 0.001). Conclusion: In this subset of patients with PSPG who underwent re-surgery, the procedure was associated with improved pain and functional outcomes. While the increase in somatosensory detection thresholds mirrors the surgery-induced cutaneous deafferentation, the increase in pressure algometry thresholds mirrors the removal of the deep "pain generator". The QST-analyses are useful adjuncts in mechanism-based somatosensory research.

A national center for persistent severe pain after groin hernia repair: Five-year prospective data.

Severe persistent pain after groin hernia repair impairs quality-of-life. Prospective, consecutive cohort study including patients with pain-related impairment of physical and social life. Relevant surgical records were obtained, and examinations were by standardized clinical and neurophysiological tests. Patients demonstrating pain sensitivity to pressure algometry in the operated groin underwent re-surgery, while patients with neuropathic pain received pharmacotherapy. Questionnaires at baseline (Q0) and at the 5-year time point (Q5Y) were used in outcome analyses of pain intensity (numeric rating scale [NRS] 0-10) and pain-related effect on the activity-of-daily-living (Activities Assessment Scale [AAS]). Data are mean (95% CI).Analyses were made in 172/204 (84%) eligible patients. In 54/172 (31%) patients re-surgery (meshectomy/selective neurectomy) was performed, while the remaining 118/172 (69%) patients received pharmacotherapy. In the re-surgery group, activity-related, and average NRS-scores at Q0 were 6.6 (5.6-7.9) and 5.9 (5.6-5.9), respectively. Correspondingly, NRS-scores at Q5Y was 4.1 (3.3-5.1) and 3.1 (2.3-4.0; Q0 vs. Q5Y: P < .0005), respectively. Although both groups experienced a significant improvement in AAS-scores comparing Q0 vs. Q5Y (re-surgery group: 28% (4-43%; P < .0001); pharmacotherapy group: 5% (0-11%; P = .005)) the improvement was significantly larger in the re-surgery group (P = .02).This 5-year cohort study in patients with severe persistent pain after groin hernia repair signals that selection to re-surgery or pharmacotherapy, based on examination of pain sensitivity, is associated with significant improvement in outcome. Analyzing composite endpoints, combining pain and physical function, are novel in exploring interventional effects.ClinicalTrials.gov Identifier NCT03713047.

A capsaicin (8%) patch in the treatment of severe persistent inguinal postherniorrhaphy pain: a randomized, double-blind, placebo-controlled trial.

BACKGROUND: Persistent pain after inguinal herniorrhaphy is a disabling condition with a lack of evidence-based pharmacological treatment options. This randomized placebo-controlled trial investigated the efficacy of a capsaicin 8% cutaneous patch in the treatment of severe persistent inguinal postherniorrhaphy pain. METHODS: Forty-six patients with persistent inguinal postherniorrhaphy pain were randomized to receive either a capsaicin 8% patch or a placebo patch. Pain intensity (Numerical Rating Scale [NRS 0-10]) was evaluated under standardized conditions (at rest, during movement, and during pressure) at baseline and at 1, 2 and 3 months after patch application. Skin punch biopsies for intraepidermal nerve fiber density (IENFD) measurements were taken at baseline and 1 month after patch application. Quantitative sensory testing was performed at baseline and at 1, 2, and 3 months after patch application. The primary outcome was comparisons of summed pain intensity differences (SPIDs) between capsaicin and placebo treatments at 1, 2 and 3 months after patch application (significance level P < 0.01). RESULTS: The maximum difference in SPID, between capsaicin and placebo treatments, was observed at 1 month after patch application, but the pain reduction was not significant (NRS, mean difference [95% CI]: 5.0 [0.09 to 9.9]; P = 0.046). No differences in SPID between treatments were observed at 2 and 3 months after patch application. Changes in IENFD on the pain side, from baseline to 1 month after patch application, did not differ between capsaicin and placebo treatment: 1.9 [-0.1 to 3.9] and 0.6 [-1.2 to 2.5] fibers/mm, respectively (P = 0.32). No significant changes in sensory function, sleep quality or psychological factors were associated with capsaicin patch treatment. CONCLUSIONS: The study did not demonstrate significant differences in pain relief between capsaicin and placebo treatment, although a trend toward pain improvement in capsaicin treated patients was observed 1 month after patch application. TRIAL REGISTRATION: Clinicaltrialsregister.eu 2012-001540-22 ClinicalTrials.gov NCT01699854.

Lidocaine patch (5%) in treatment of persistent inguinal postherniorrhaphy pain: a randomized, double-blind, placebo-controlled, crossover trial.

BACKGROUND: Evidence-based pharmacological treatment options for patients with persistent inguinal postherniorrhaphy pain are lacking. METHODS: Twenty-one male patients, with severe, unilateral, persistent inguinal postherniorrhaphy pain, participated in a randomized, double-blind, placebo-controlled crossover trial, receiving lidocaine patch (5%) and placebo patch treatments in periods of 14 days separated by a 14-day wash-out period. Pain intensities (at rest, during movement, and pressure evoked [Numerical Rating Scale]) were assessed before treatment and on the last 3 days of each treatment period. Patients were a priori divided into two subgroups based on quantitative sensory testing (+/- thermal "hyposensitivity"). Skin biopsies for intraepidermal nerve fiber density assessment were taken at baseline, and quantitative sensory testing was performed before and after each treatment period. The primary outcome was change in pain intensity assessed as the difference in summed pain intensity differences between lidocaine and placebo patch treatments. RESULTS: There was no difference in summed pain intensity differences between lidocaine and placebo patch treatments in all patients (mean difference 6.2% [95% CI = -6.6 to 18.9%]; P = 0.33) or in the two subgroups (+/- thermal "hyposensitivity"). The quantitative sensory testing (n = 21) demonstrated an increased pressure pain thresholds after lidocaine compared with placebo patch treatment. Baseline intraepidermal nerve fiber density (n = 21) was lower on the pain side compared with the nonpain side (-3.8 fibers per millimeter [95% CI = -6.1 to -1.4]; P = 0.003). One patient developed mild erythema in the groin during both treatments. CONCLUSIONS: Lidocaine patch treatment did not reduce combined resting and dynamic pain ratings compared with placebo in patients with severe, persistent inguinal postherniorrhaphy pain.

Ultrasound-guided ilioinguinal/iliohypogastric nerve blocks for persistent inguinal postherniorrhaphy pain: a randomized, double-blind, placebo-controlled, crossover trial.

BACKGROUND: Ilioinguinal and iliohypogastric nerve blocks are used in the clinical management of persistent inguinal postherniorrhaphy pain, but no controlled studies have been published on the subject. In this controlled study, we investigated the analgesic and sensory effects of ultrasound-guided blocks of the ilioinguinal and iliohypogastric nerves with lidocaine. METHODS: A randomized, double-blind, placebo-controlled, crossover trial in 12 patients with severe persistent inguinal postherniorrhaphy pain, including a control group of 12 healthy controls, was performed. Assessments included pain ratings under standardized conditions with numerical rating scale (0-10), sensory mapping to a cool roller, and quantitative sensory testing (QST), in the groin regions, before and after each ultrasound-guided block. A needle approach of 1 to 2 cm superior and medial to the anterior superior iliac spine was used. Outcomes were changes in pain ratings, sensory mapping, and QST compared with preblock values. Lidocaine responders were a priori defined by a pain reduction of ≥80% after lidocaine block and ≤25% after placebo block, nonresponders by pain reduction of <80% after lidocaine block and ≤25% after placebo block, and placebo responders by pain reduction of >25% after placebo block. RESULTS: One of 12 pain patients was a lidocaine responder, 6 patients were nonresponders, and 5 patients were placebo responders. No consistent QST changes were observed in patients after the lidocaine block. In 10 of 12 healthy controls, a cool hypoesthesia area developed in the groin after the lidocaine block. Furthermore, QST assessments demonstrated significantly decreased suprathreshold heat pain perception in the groin after lidocaine versus placebo blocks (95% confidence interval = -3.5 to -0.5, P = 0.008). CONCLUSION: Ultrasound-guided lidocaine blocks of the ilioinguinal and iliohypogastric nerves, at the level of the anterior superior iliac spine, are not useful in diagnosis and management of persistent inguinal postherniorrhaphy pain.

Pulsed radiofrequency in the treatment of persistent pain after inguinal herniotomy: a systematic review.

In the United States, it is estimated that between 6000 and 18,000 individuals each year present with disabling pain after inguinal hernia repair. Although surgical treatment with mesh removal is one of few options available, effective alternatives to nonsurgical management are needed. The use of pulsed radiofrequency (PFR), leading to nondestructive lesions of nerve structures, has been proposed as a treatment option. To examine the evidence of treatment efficacy, a systematic literature search was made. From the databases PubMed, Embase, and CINAHL, 4 case reports were retrieved and 8 patients were included for analysis. The PFR treatment was peripheral (n = 4) and central (n = 4). Pain relief varied between 63% and 100%, the follow-up period was 3 to 9 months, and no adverse effects or complications were reported. In conclusion, the evidence base of PRF in persistent pain after inguinal herniotomy is fairly limited. Suggestions for improved research strategies are presented.

Dysejaculation after laparoscopic inguinal herniorrhaphy: a nationwide questionnaire study.

BACKGROUND: Dysejaculation and pain from the groin and genitals during sexual activity represent a clinically significant problem in up to 4% of younger males after open inguinal herniorrhaphy. The aim of this questionnaire study is to assess the prevalence of dysejaculation and pain during sexual activity after laparoscopic inguinal herniorrhaphy on a nationwide basis. METHODS: The study population comprised all men aged 18-50 years registered in the Danish Hernia Database (n = 1,671) who underwent primary laparoscopic herniorrhaphy between January 1, 1998 and November 30, 2009. Questionnaires regarding dysejaculation and pain during sexual activity were mailed 3 months to 12 years after surgery, and 1,172 patients were included for analysis. RESULTS: The response rate was 68.7% (n = 805). Dysejaculation occurring after laparoscopic repair was present in 25 patients (3.1%). Pain from the groin or genitals during sexual activity was reported by 88 patients (10.9%), and 19 patients (2.4%) reported that the pain had impaired their sexual activity to a moderate or severe degree. Older patients and patients with longer follow-up had lower prevalence of pain during sexual activity. CONCLUSIONS: Dysejaculation and pain-related impairment of sexual activity is a significant problem after laparoscopic inguinal herniorrhaphy. The role of improved laparoscopic technique with use of glue fixation of lightweight meshes to reduce the risk of developing these complications needs to be evaluated.