Pain Management
REVIEW EDITORIAL For reprint orders, please contact: [email protected]
Persistent pain following groin hernia repair: what is the best practice in pain management?
Mads U Werner*,1 & Thomas P Enggaard1 Severe persistent pain after planned groin hernia repair (GHR) is a procedural complication affecting 2–4% of the patients following surgery, a procedure normally considered minor [1] . This postsurgical pain condition may lead to functional and socioeconomic disability [2,3] and since GHR is a commonly performed procedure, it can be estimated that 6000 to 18,000 individuals each year in the USA [4] alone will develop debilitating persistent pain, related to this surgery. Surgical aspects GHR, performed either as an open or a laparoscopical procedure, includes implantation of a synthetic nonbiodegradable mesh (polypropylene or polyester) placed over the defect and anchored with sutures or staples, respectively. The implanted prosthetic material induces a sustained foreign-body reaction with formation of giant-cell granulomas, production of interleukines and deposition of fibrotic tissue [5] . Although these processes generally are biocompatible, perturbations leading to severe pathological repercussions occur [5,6] .
Pathophysiological aspects Several pathophysiological mechanisms behind persistent postsurgical pain in GHR have been presented [1,7–9] . The implanted mesh undergoes considerable shrinkage due to the inflammatory reaction [10] , in excessive cases developing into a ‘meshoma’. Inadequate biointegration of the prosthetic material [11] in the soft tissues of groin may lead to movementrelated pain or uncomfortable sensations of rigidity. Other mechanical causes of pain are partial dislocation or dehiscence of the mesh interfering with movement. The majority of patients present with localized mechanical pain at the superficial inguinal ring, easily quantifiable with pressure algometry [12] . Excessive tenderness, corroborated by low pressure pain thresholds, in part represent compression of the spermatic cord by the conglomerate of the prosthetic material and the inflammatory tissue. Some of these patients in addition demonstrate signs of entrapment of the genital branch of the genitofemoral nerve, and, the ilioinguinal nerve, experiencing a tender spermatic cord, projected testicular and scrotal pain, dysejaculation
KEYWORDS
• disability • groin hernia repair • management • patho physiology • persistent postsurgical pain • prediction • prevention • surgery
“Severe persistent pain after planned groin hernia repair is a procedural complication affecting 2–4% of the patients following surgery … this postsurgical pain condition may lead to functional and socioeconomic disability … it can be estimated that 6000 to 18,000 individuals each year in the USA alone will develop debilitating persistent pain, related to this surgery.”
Multidisciplinary Pain Center, Neuroscience Center, Rigshospitalet, Copenhagen University Hospitals, Copenhagen, Denmark *Author for correspondence: Tel.: +45 2825 7703; Fax: +45 3545 6543; [email protected] 1
10.2217/PMT.15.1 © 2015 Future Medicine Ltd
Pain Manag. (2015) 5(2), 65–68
part of
ISSN 1758-1869
65
Editorial Werner & Enggaard and cutaneous sensory abnormalities of the proximal, medial part of the thigh. During exploratory groin surgery, aimed at removing the mesh, it becomes apparent that also branches of the iliohypogastric and ilioinguinal nerves, very often severely damaged are embedded in the inflammatory tissue surrounding the mesh. Unfortunately, at the moment, we are not able with any method to reliably distinguish between inflammatory and neuropathic components of persistent postsurgical pain. Furthermore, longitudinal data indicate that more than two-thirds of the patients with persistent pain after GHR develop their chronic pain state from months to several years after the primary surgery [1] : development of persistent postsurgical pain thus cannot be considered to follow a stereotype trajectory from acute to persistent pain. Behavioral consequences Several questionnaire studies on health-related quality-of-life after GHR have demonstrated that 15–30% of individuals experience pain from the groin when standing up more than 30 min, climbing stairs, sitting more than 30 min or getting up from a chair, and, that these physical restrictions significantly may affect work and exercise capacity [8] . In addition, moderate-tosevere impairment in sexual activity, in other words movement-related pain or dysejaculation, as complications to GHR have been identified in 5% [13,14] . Unfortunately, in-depth demographic studies of the socioeconomic and psychosocial consequences of these physical disabilities have not been performed. Management
66
integrity of only one of the three nerves supplying the area required for maintaining the persistent pain state? Furthermore, the beneficial role of repeated blocks with local anesthetics or the addition of glucocorticoids, commonly used in clinical practice, has not been investigated. ●●Topical analgesics
Topical analgesia with lidocaine patches (5%) has been recommended as a first-line treatment in peripheral neuropathic pain with localized sensory dysfunction. Again, only one randomized, double-blind, controlled crossover study is available and though increased pressure pain thresholds were observed in the lidocaine group, compared with the control group, no overall effect on resting and dynamic pain-ratings were demonstrated [16] . Topical treatment with capsaicin (8%), the pungent ingredient of chili peppers, has been evaluated in one randomized, double-blind, controlled parallel study [17] . Application of the capsaicin patches was not associated with statistically significant pain relief compared with controls, although a trend toward pain improvement in capsaicin-treated patients was observed 1 month after patch application (p-values 0.024–0.046; significance level set a priori to 0.01). Interestingly, the data indicate that a correlation between the intraepithelial nerve fiber density and a positive treatment outcome may exist, implying that individuals with intact thermal and mechanical cutaneous sensation would benefit most from capsaicin treatment. However, the authors pointed at several potential confounding factors might have affected the study results.
●●Blockades
●●Systemic analgesics
Only one randomized, double-blind, controlled crossover study has presented data on nerveblocks in persistent pain following GHR [15] . Using an ultrasound-guided block of the iliohypogastric and ilioinguinal nerves with a shortacting local anesthetic, no significant effect on resting or dynamic pain-ratings were seen, while, interestingly, a notable placebo-response was evident. Importantly, the procedure was in addition performed in healthy volunteers demonstrating distinct block-effects assessed by quantitative sensory testing. More studies are clearly needed to characterize the afferent nociceptive input from the pain area: does the genital branch of the genitofemoral nerve constitute the main transmission pathway, or is the conduction
Vis-à-vis systemically acting analgesics only one procedure-specific study is available [18] . In this randomized, double-blind, controlled study, a single dose of gabapentin 1200 mg administered immediately before GHR, was associated with significantly lower resting pain-ratings 6 months after surgery, documented by a telephone interview. However, the recorded pain intensities were very low and hardly of any clinical significance for patients with persistent postsurgical pain.
Pain Manag. (2015) 5(2)
●●Neuromodulation
In regard to neuromodulation techniques, pulsed radiofrequency, continuous radiofrequency, spinal cord stimulation of the dorsal root ganglion [19] and peripheral nerve stimulation,
future science group
Groin hernia repair: the best practice in pain management utilizing a transperitoneal laparoscopic approach, have been used with pain relieving effects in a number of patients. A recent review however concluded: “Although preliminary reports with neuromodulation techniques are enthusiastic and promising the evidence is still of low quality, and the strength of recommendation is weak to moderate. The scientific rigor is generally not considered adequate and study designs should be improved in regard to control groups, randomization, blinding procedures and adequate sampling sizes” [1] . ●●Surgery
A disproportionately higher prevalence of surgical than on medical studies exists in the literature [1] . Although some methodological shortcomings in these studies are evident, the large bulk of data demonstrates that selective or triple neurectomy, with or without mesh removal, may provide long-lasting analgesic effects in most patients with severe persistent postsurgical pain after GHR. Authoritative hernia surgeons have stated that “….different types of neurectomy with or without mesh removal should be regarded as the last treatment option…” [7] indicating that surgery on the peripheral nervous system during certain conditions may lead to untoward outcomes [1] . Improved surgical study designs are needed and implementation of multicenter collaborative approaches supplying consistent, reliable long-term data would facilitate the evaluation of optimal surgical techniques [7] . Prevention Preventive measures targeted at development of severe persistent postsurgical pain should consider indication criteria for GHR, preoperative prediction of pain vulnerability and optimization of surgical techniques. ‘Watchful waiting’ is an acceptable option to GHR in males with minimally symptomatic groin hernias, since acute intestinal obstruction or strangulation rarely occurs [20] . However, in females, it is advisable to offer laparoscopic repair due to an increased risk of strangulation. The patient’s vulnerability to develop severe persistent postsurgical pain are influenced by three risk factors: preoperative sensitivity to a short phasic heat stimulus, preoperative physical impairment status and surgery performed by an open procedure [21] . If the preoperative assessments indicate a high susceptibility, the patient should be
future science group
Editorial
allocated to a laparoscopic technique that could reduce the risk of severe persistent postsurgical pain with 50% compared with the open technique [8] . A number of other surgical factors may potentially influence the outcome: the anatomical approach, the use of light-weight mesh, the mesh fabric (biological vs synthetic) and the fixation technique (glue vs tacks/staples/ sutures) [7] . Conclusion The procedure-specific evidence-base for clinical management of persistent pain after GHR is rather meagre considering that it is a highflow procedure with 2000 surgeries annually per one million residents. Moreover, GHR is a surgical model extremely well qualified for studying pathophysiological mechanisms, preventive measures and management of persistent postsurgical pain states. Compared with other patient cohorts with postsurgical pain, most of the GHR patients are of working age, present with few concomitant diseases; and rarely suffer from malignancies, demonstrate significant psychosocial issues, present with a complex medication list and do only rarely suffer from concurrent chronic pain. What is the best practice in pain management? Although exploratory surgery with selective neurectomy and mesh removal definitely has a prominent place in the management, less invasive methods should be tried first, since the indications for exploratory surgery have not yet been clearly defined and the risk of development of a deafferentiation syndrome following neurectomy still weighs as a potential threat. On the other hand, if conventional (evidence-lacking) therapies with analgesics and antihyperalgesics do not lead to adequate pain relief, the surgical option should undoubtedly be considered and could likely be of instrumental value to the patient. Financial & competing interests disclosure MU Werner has received unrestricted research grants, administered by the University Hospital’s Administration, from Grünenthal GmbH, Germany and Astellas Pharma A/S, Denmark. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed. No writing assistance was utilized in the production of this manuscript.
www.futuremedicine.com
67
Editorial Werner & Enggaard cancer surgery. Curr. Top. Behav. Neurosci. 20, 3–9 (2014).
References 1
2
3
4
5
6
7
8
68
Werner MU. Management of persistent postsurgical inguinal pain. Langenbecks Arch. Surg. 399(5), 559–569 (2014). Bay-Nielsen M, Perkins FM, Kehlet H. Pain and functional impairment one year after inguinal herniorrhaphy - a nationwide questionnaire study. Ann. Surg. 233(1), 1–7 (2001). Loos MJ, Roumen RM, Scheltinga MR. Chronic sequelae of common elective groin hernia repair. Hernia 11(2), 169–173 (2007). SAGES. Society of American Gastrointestinal and Endoscopic Surgeons. www.sages.org/publication/id/PI06/ Ansaloni L, Catena F, Coccolini F, Negro P, Campanelli G, Miserez M. New “biological” meshes: the need for a register. The EHS Registry for Biological Prostheses: call for participating European surgeons. Hernia 13(1), 103–108 (2009). Ostergard DR. Degradation, infection and heat effects on polypropylene mesh for pelvic implantation: what was known and when it was known. Int. Urogynecol. J. 22(7), 771–774 (2011). Kehlet H, Roumen RM, Reinpold W, Miserez M. Invited commentary: persistent pain after inguinal hernia repair: what do we know and what do we need to know? Hernia 17(3), 293–297 (2013). Werner MU, Bischoff JM. Persistent postsurgical pain: evidence from breast cancer surgery, groin hernia repair, and lung
9
Werner MU, Kongsgaard UE. I. Defining persistent post-surgical pain: is an update required? Br. J. Anaesth. 113(1), 1–4 (2014).
10 Tanaka K, Mutter D, Inoue H et al. In vivo
evaluation of a new composite mesh (10% polypropylene/90% poly-l-lactic acid) for hernia repair. J. Mater. Sci. Mater. Med. 18(6), 991–999 (2007). 11 Schäfer-Nolte F, Hennecke K,
Reimers K et al. Biomechanics and biocompatibility of woven spider silk meshes during remodeling in a rodent fascia replacement model. Ann. Surg. 259(4), 781–792 (2014). 12 Bischoff JM, Enghuus C, Werner MU,
Kehlet H. Long-term follow-up after mesh removal and selective neurectomy for persistent inguinal postherniorrhaphy pain. Hernia 17(3), 339–345 (2013). 13 Aasvang EK, Mohl B, Kehlet H. Ejaculatory
pain: a specific postherniotomy pain syndrome? Anesthesiology 107(2), 298–304 (2007). 14 Bischoff JM, Linderoth G, Aasvang EK,
Werner MU, Kehlet H. Dysejaculation after laparoscopic inguinal herniorrhaphy: a nationwide questionnaire study. Surg. Endosc. 26(4), 979–983 (2012). 15 Bischoff JM, Koscielniak-Nielsen ZJ,
Kehlet H, Werner MU. Ultrasound-guided ilioinguinal/iliohypogastric nerve blocks for persistent inguinal postherniorrhaphy pain: a randomized, double-blind, placebo-
Pain Manag. (2015) 5(2)
controlled, crossover trial. Anesth. Analg. 114(6), 1323–1329 (2012). 16 Bischoff JM, Petersen M, Uceyler N,
Sommer C, Kehlet H, Werner MU. Lidocaine patch (5%) in treatment of persistent inguinal postherniorrhaphy pain: a randomized, double-blind, placebo-controlled, crossover trial. Anesthesiology 119, 1444–1452 (2013). 17 Bischoff JM, Ringsted TK, Petersen M,
Sommer C, Uceyler N, Werner MU. A capsaicin (8%) patch in the treatment of severe persistent inguinal postherniorrhaphy pain: a randomized, double-blind, placebocontrolled trial. PLoS ONE 9(10), e109144 (2014). 18 Sen H, Sizlan A, Yanarates O et al. The
effects of gabapentin on acute and chronic pain after inguinal herniorrhaphy. Eur. J. Anaesthesiol. 26(9), 772–776 (2009). 19 Schu S, Gulve A, Eldabe S et al. Spinal cord
stimulation of the dorsal root ganglion for groin pain: a retrospective review. Pain Pract. doi:10.1111/papr.12194 (2014) (Epub ahead of print). 20 Rosenberg J, Bisgaard T, Kehlet H et al.
Danish Hernia Database recommendations for the management of inguinal and femoral hernia in adults. Dan. Med. Bull. 58(2), C4243 (2011). 21 Aasvang EK, Gmaehle E, Hansen JB et al.
Predictive risk factors for persistent postherniotomy pain. Anesthesiology 112(4), 957–969 (2010).
future science group
REVIEW EDITORIAL For reprint orders, please contact: [email protected]
Persistent pain following groin hernia repair: what is the best practice in pain management?
Mads U Werner*,1 & Thomas P Enggaard1 Severe persistent pain after planned groin hernia repair (GHR) is a procedural complication affecting 2–4% of the patients following surgery, a procedure normally considered minor [1] . This postsurgical pain condition may lead to functional and socioeconomic disability [2,3] and since GHR is a commonly performed procedure, it can be estimated that 6000 to 18,000 individuals each year in the USA [4] alone will develop debilitating persistent pain, related to this surgery. Surgical aspects GHR, performed either as an open or a laparoscopical procedure, includes implantation of a synthetic nonbiodegradable mesh (polypropylene or polyester) placed over the defect and anchored with sutures or staples, respectively. The implanted prosthetic material induces a sustained foreign-body reaction with formation of giant-cell granulomas, production of interleukines and deposition of fibrotic tissue [5] . Although these processes generally are biocompatible, perturbations leading to severe pathological repercussions occur [5,6] .
Pathophysiological aspects Several pathophysiological mechanisms behind persistent postsurgical pain in GHR have been presented [1,7–9] . The implanted mesh undergoes considerable shrinkage due to the inflammatory reaction [10] , in excessive cases developing into a ‘meshoma’. Inadequate biointegration of the prosthetic material [11] in the soft tissues of groin may lead to movementrelated pain or uncomfortable sensations of rigidity. Other mechanical causes of pain are partial dislocation or dehiscence of the mesh interfering with movement. The majority of patients present with localized mechanical pain at the superficial inguinal ring, easily quantifiable with pressure algometry [12] . Excessive tenderness, corroborated by low pressure pain thresholds, in part represent compression of the spermatic cord by the conglomerate of the prosthetic material and the inflammatory tissue. Some of these patients in addition demonstrate signs of entrapment of the genital branch of the genitofemoral nerve, and, the ilioinguinal nerve, experiencing a tender spermatic cord, projected testicular and scrotal pain, dysejaculation
KEYWORDS
• disability • groin hernia repair • management • patho physiology • persistent postsurgical pain • prediction • prevention • surgery
“Severe persistent pain after planned groin hernia repair is a procedural complication affecting 2–4% of the patients following surgery … this postsurgical pain condition may lead to functional and socioeconomic disability … it can be estimated that 6000 to 18,000 individuals each year in the USA alone will develop debilitating persistent pain, related to this surgery.”
Multidisciplinary Pain Center, Neuroscience Center, Rigshospitalet, Copenhagen University Hospitals, Copenhagen, Denmark *Author for correspondence: Tel.: +45 2825 7703; Fax: +45 3545 6543; [email protected] 1
10.2217/PMT.15.1 © 2015 Future Medicine Ltd
Pain Manag. (2015) 5(2), 65–68
part of
ISSN 1758-1869
65
Editorial Werner & Enggaard and cutaneous sensory abnormalities of the proximal, medial part of the thigh. During exploratory groin surgery, aimed at removing the mesh, it becomes apparent that also branches of the iliohypogastric and ilioinguinal nerves, very often severely damaged are embedded in the inflammatory tissue surrounding the mesh. Unfortunately, at the moment, we are not able with any method to reliably distinguish between inflammatory and neuropathic components of persistent postsurgical pain. Furthermore, longitudinal data indicate that more than two-thirds of the patients with persistent pain after GHR develop their chronic pain state from months to several years after the primary surgery [1] : development of persistent postsurgical pain thus cannot be considered to follow a stereotype trajectory from acute to persistent pain. Behavioral consequences Several questionnaire studies on health-related quality-of-life after GHR have demonstrated that 15–30% of individuals experience pain from the groin when standing up more than 30 min, climbing stairs, sitting more than 30 min or getting up from a chair, and, that these physical restrictions significantly may affect work and exercise capacity [8] . In addition, moderate-tosevere impairment in sexual activity, in other words movement-related pain or dysejaculation, as complications to GHR have been identified in 5% [13,14] . Unfortunately, in-depth demographic studies of the socioeconomic and psychosocial consequences of these physical disabilities have not been performed. Management
66
integrity of only one of the three nerves supplying the area required for maintaining the persistent pain state? Furthermore, the beneficial role of repeated blocks with local anesthetics or the addition of glucocorticoids, commonly used in clinical practice, has not been investigated. ●●Topical analgesics
Topical analgesia with lidocaine patches (5%) has been recommended as a first-line treatment in peripheral neuropathic pain with localized sensory dysfunction. Again, only one randomized, double-blind, controlled crossover study is available and though increased pressure pain thresholds were observed in the lidocaine group, compared with the control group, no overall effect on resting and dynamic pain-ratings were demonstrated [16] . Topical treatment with capsaicin (8%), the pungent ingredient of chili peppers, has been evaluated in one randomized, double-blind, controlled parallel study [17] . Application of the capsaicin patches was not associated with statistically significant pain relief compared with controls, although a trend toward pain improvement in capsaicin-treated patients was observed 1 month after patch application (p-values 0.024–0.046; significance level set a priori to 0.01). Interestingly, the data indicate that a correlation between the intraepithelial nerve fiber density and a positive treatment outcome may exist, implying that individuals with intact thermal and mechanical cutaneous sensation would benefit most from capsaicin treatment. However, the authors pointed at several potential confounding factors might have affected the study results.
●●Blockades
●●Systemic analgesics
Only one randomized, double-blind, controlled crossover study has presented data on nerveblocks in persistent pain following GHR [15] . Using an ultrasound-guided block of the iliohypogastric and ilioinguinal nerves with a shortacting local anesthetic, no significant effect on resting or dynamic pain-ratings were seen, while, interestingly, a notable placebo-response was evident. Importantly, the procedure was in addition performed in healthy volunteers demonstrating distinct block-effects assessed by quantitative sensory testing. More studies are clearly needed to characterize the afferent nociceptive input from the pain area: does the genital branch of the genitofemoral nerve constitute the main transmission pathway, or is the conduction
Vis-à-vis systemically acting analgesics only one procedure-specific study is available [18] . In this randomized, double-blind, controlled study, a single dose of gabapentin 1200 mg administered immediately before GHR, was associated with significantly lower resting pain-ratings 6 months after surgery, documented by a telephone interview. However, the recorded pain intensities were very low and hardly of any clinical significance for patients with persistent postsurgical pain.
Pain Manag. (2015) 5(2)
●●Neuromodulation
In regard to neuromodulation techniques, pulsed radiofrequency, continuous radiofrequency, spinal cord stimulation of the dorsal root ganglion [19] and peripheral nerve stimulation,
future science group
Groin hernia repair: the best practice in pain management utilizing a transperitoneal laparoscopic approach, have been used with pain relieving effects in a number of patients. A recent review however concluded: “Although preliminary reports with neuromodulation techniques are enthusiastic and promising the evidence is still of low quality, and the strength of recommendation is weak to moderate. The scientific rigor is generally not considered adequate and study designs should be improved in regard to control groups, randomization, blinding procedures and adequate sampling sizes” [1] . ●●Surgery
A disproportionately higher prevalence of surgical than on medical studies exists in the literature [1] . Although some methodological shortcomings in these studies are evident, the large bulk of data demonstrates that selective or triple neurectomy, with or without mesh removal, may provide long-lasting analgesic effects in most patients with severe persistent postsurgical pain after GHR. Authoritative hernia surgeons have stated that “….different types of neurectomy with or without mesh removal should be regarded as the last treatment option…” [7] indicating that surgery on the peripheral nervous system during certain conditions may lead to untoward outcomes [1] . Improved surgical study designs are needed and implementation of multicenter collaborative approaches supplying consistent, reliable long-term data would facilitate the evaluation of optimal surgical techniques [7] . Prevention Preventive measures targeted at development of severe persistent postsurgical pain should consider indication criteria for GHR, preoperative prediction of pain vulnerability and optimization of surgical techniques. ‘Watchful waiting’ is an acceptable option to GHR in males with minimally symptomatic groin hernias, since acute intestinal obstruction or strangulation rarely occurs [20] . However, in females, it is advisable to offer laparoscopic repair due to an increased risk of strangulation. The patient’s vulnerability to develop severe persistent postsurgical pain are influenced by three risk factors: preoperative sensitivity to a short phasic heat stimulus, preoperative physical impairment status and surgery performed by an open procedure [21] . If the preoperative assessments indicate a high susceptibility, the patient should be
future science group
Editorial
allocated to a laparoscopic technique that could reduce the risk of severe persistent postsurgical pain with 50% compared with the open technique [8] . A number of other surgical factors may potentially influence the outcome: the anatomical approach, the use of light-weight mesh, the mesh fabric (biological vs synthetic) and the fixation technique (glue vs tacks/staples/ sutures) [7] . Conclusion The procedure-specific evidence-base for clinical management of persistent pain after GHR is rather meagre considering that it is a highflow procedure with 2000 surgeries annually per one million residents. Moreover, GHR is a surgical model extremely well qualified for studying pathophysiological mechanisms, preventive measures and management of persistent postsurgical pain states. Compared with other patient cohorts with postsurgical pain, most of the GHR patients are of working age, present with few concomitant diseases; and rarely suffer from malignancies, demonstrate significant psychosocial issues, present with a complex medication list and do only rarely suffer from concurrent chronic pain. What is the best practice in pain management? Although exploratory surgery with selective neurectomy and mesh removal definitely has a prominent place in the management, less invasive methods should be tried first, since the indications for exploratory surgery have not yet been clearly defined and the risk of development of a deafferentiation syndrome following neurectomy still weighs as a potential threat. On the other hand, if conventional (evidence-lacking) therapies with analgesics and antihyperalgesics do not lead to adequate pain relief, the surgical option should undoubtedly be considered and could likely be of instrumental value to the patient. Financial & competing interests disclosure MU Werner has received unrestricted research grants, administered by the University Hospital’s Administration, from Grünenthal GmbH, Germany and Astellas Pharma A/S, Denmark. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed. No writing assistance was utilized in the production of this manuscript.
www.futuremedicine.com
67
Editorial Werner & Enggaard cancer surgery. Curr. Top. Behav. Neurosci. 20, 3–9 (2014).
References 1
2
3
4
5
6
7
8
68
Werner MU. Management of persistent postsurgical inguinal pain. Langenbecks Arch. Surg. 399(5), 559–569 (2014). Bay-Nielsen M, Perkins FM, Kehlet H. Pain and functional impairment one year after inguinal herniorrhaphy - a nationwide questionnaire study. Ann. Surg. 233(1), 1–7 (2001). Loos MJ, Roumen RM, Scheltinga MR. Chronic sequelae of common elective groin hernia repair. Hernia 11(2), 169–173 (2007). SAGES. Society of American Gastrointestinal and Endoscopic Surgeons. www.sages.org/publication/id/PI06/ Ansaloni L, Catena F, Coccolini F, Negro P, Campanelli G, Miserez M. New “biological” meshes: the need for a register. The EHS Registry for Biological Prostheses: call for participating European surgeons. Hernia 13(1), 103–108 (2009). Ostergard DR. Degradation, infection and heat effects on polypropylene mesh for pelvic implantation: what was known and when it was known. Int. Urogynecol. J. 22(7), 771–774 (2011). Kehlet H, Roumen RM, Reinpold W, Miserez M. Invited commentary: persistent pain after inguinal hernia repair: what do we know and what do we need to know? Hernia 17(3), 293–297 (2013). Werner MU, Bischoff JM. Persistent postsurgical pain: evidence from breast cancer surgery, groin hernia repair, and lung
9
Werner MU, Kongsgaard UE. I. Defining persistent post-surgical pain: is an update required? Br. J. Anaesth. 113(1), 1–4 (2014).
10 Tanaka K, Mutter D, Inoue H et al. In vivo
evaluation of a new composite mesh (10% polypropylene/90% poly-l-lactic acid) for hernia repair. J. Mater. Sci. Mater. Med. 18(6), 991–999 (2007). 11 Schäfer-Nolte F, Hennecke K,
Reimers K et al. Biomechanics and biocompatibility of woven spider silk meshes during remodeling in a rodent fascia replacement model. Ann. Surg. 259(4), 781–792 (2014). 12 Bischoff JM, Enghuus C, Werner MU,
Kehlet H. Long-term follow-up after mesh removal and selective neurectomy for persistent inguinal postherniorrhaphy pain. Hernia 17(3), 339–345 (2013). 13 Aasvang EK, Mohl B, Kehlet H. Ejaculatory
pain: a specific postherniotomy pain syndrome? Anesthesiology 107(2), 298–304 (2007). 14 Bischoff JM, Linderoth G, Aasvang EK,
Werner MU, Kehlet H. Dysejaculation after laparoscopic inguinal herniorrhaphy: a nationwide questionnaire study. Surg. Endosc. 26(4), 979–983 (2012). 15 Bischoff JM, Koscielniak-Nielsen ZJ,
Kehlet H, Werner MU. Ultrasound-guided ilioinguinal/iliohypogastric nerve blocks for persistent inguinal postherniorrhaphy pain: a randomized, double-blind, placebo-
Pain Manag. (2015) 5(2)
controlled, crossover trial. Anesth. Analg. 114(6), 1323–1329 (2012). 16 Bischoff JM, Petersen M, Uceyler N,
Sommer C, Kehlet H, Werner MU. Lidocaine patch (5%) in treatment of persistent inguinal postherniorrhaphy pain: a randomized, double-blind, placebo-controlled, crossover trial. Anesthesiology 119, 1444–1452 (2013). 17 Bischoff JM, Ringsted TK, Petersen M,
Sommer C, Uceyler N, Werner MU. A capsaicin (8%) patch in the treatment of severe persistent inguinal postherniorrhaphy pain: a randomized, double-blind, placebocontrolled trial. PLoS ONE 9(10), e109144 (2014). 18 Sen H, Sizlan A, Yanarates O et al. The
effects of gabapentin on acute and chronic pain after inguinal herniorrhaphy. Eur. J. Anaesthesiol. 26(9), 772–776 (2009). 19 Schu S, Gulve A, Eldabe S et al. Spinal cord
stimulation of the dorsal root ganglion for groin pain: a retrospective review. Pain Pract. doi:10.1111/papr.12194 (2014) (Epub ahead of print). 20 Rosenberg J, Bisgaard T, Kehlet H et al.
Danish Hernia Database recommendations for the management of inguinal and femoral hernia in adults. Dan. Med. Bull. 58(2), C4243 (2011). 21 Aasvang EK, Gmaehle E, Hansen JB et al.
Predictive risk factors for persistent postherniotomy pain. Anesthesiology 112(4), 957–969 (2010).
future science group
