Eske Kvanner Aasvang

Predictive Risk Factors for Persistent Postherniotomy Pain

Background:Persistent postherniotomy pain (PPP) affects everyday activities in 5–10% of patients. Identification of predisposing factors may help to identify the risk groups and guide anesthetic or surgical procedures in reducing risk for PPP. Methods:A prospective study was conducted in 464 patients undergoing open or laparoscopic transabdominal preperitoneal elective groin hernia repair. Primary outcome was identification of risk factors for substantial pain-related functional impairment at 6 months postoperatively assessed by the validated Activity Assessment Scale (AAS). Data on potential risk factors for PPP were collected preoperatively (pain from the groin hernia, preoperative AAS score, pain from other body regions, and psychometric assessment). Pain scores were collected on days 7 and 30 postoperatively. Sensory functions including pain response to tonic heat stimulation were assessed by quantitative sensory testing preoperatively and 6 months postoperatively to assess nerve damage. Results:Four hundred sixty-four patients were included, whereof 442 were examined at 6 months (95.3% follow-up). Fifty-five patients (12.4%) had “moderate/severe” PPP at 6 months. Logistic regression analysis identified four risk factors for PPP: preoperative AAS score, preoperative pain to tonic heat stimulation, 30-day postoperative pain intensity, and sensory dysfunction in the groin at 6 months (nerve damage) (all P < 0.03). A risk prediction model of only preoperative factors and choice of surgical technique revealed increased preoperative AAS score, increased preoperative pain to heat stimulation, and open surgery to increase the risk for PPP (all P < 0.02). Conclusion:PPP is related to both patient and surgical factors. Patients with a high preoperative AAS score and high pain response to a standardized heat stimulus may preferably be treated using an operative technique with lowest risk for nerve damage.

Surgical management of chronic pain after inguinal hernia repair

Chronic pain after inguinal hernia repair is an adverse outcome that affects about 12 per cent of patients. Principles of treatment have not been defined. This review examines neurectomy and mesh or staple removal as possible treatments.

Neurophysiological characterization of postherniotomy pain

&NA; Inguinal herniotomy is one of the most frequent surgical procedures and chronic pain affecting everyday activities is reported in ∼10% of patients. However, the neurophysiological changes and underlying pathophysiological mechanisms of postherniotomy pain are not known in detail, thereby precluding advances in treatment strategies and prophylaxis. Therefore, we examined forty‐six patients reporting moderate to severe postherniotomy pain affecting daily activities for more than a year postoperatively, and compared them with a control group of patients without pain 1 yr postoperatively. A quantitative sensory testing protocol was used, assessing sensory dysfunction type, location and severity. We assessed the protocol test–retest variability using data from healthy control subjects. All patients (pain and pain‐free) had signs of nerve damage, seen as sensory dysfunction. Detection thresholds for tactile and warmth stimulation were significantly increased while cold detection and pressure pain detection thresholds were significantly decreased in pain patients compared to controls. Repetitive punctuate and brush stimulation resulted in significantly more frequent and intense pain on the painful side than on the unaffected side in pain patients, and was not observed in controls. Our findings showed large and small fiber dysfunction in both pain and pain‐free patients but more profound in pain patients and with signs of central sensitization (abnormal temporal summation). The specific finding of reduced pain detection threshold over the external inguinal annulus is consistent with damage to the cutaneous innervation territory of nervous structures in the inguinal region. The correspondence between pain location and sensory disturbance suggests that the pain is neuropathic in nature. Whether the underlying pathophysiological mechanisms are related to direct intraoperative nerve injury or nerve injury due to an inflammatory mesh response remains to be determined.

Pain related sexual dysfunction after inguinal herniorrhaphy

Abstract To determine the incidence of pain related sexual dysfunction 1 year after inguinal herniorrhaphy and to assess the impact pain has on sexual function. In contrast to the well‐described about 10% risk of chronic wound related pain after inguinal herniorrhaphy, chronic genital pain, dysejaculation, and sexual dysfunction have only been described sporadically. The aim was therefore to describe these symptoms in a questionnaire study. A nationwide detailed questionnaire study in September 2004 of pain related sexual dysfunction in all men aged 18–40 years undergoing inguinal herniorrhaphy between October 2002 and June 2003 (n = 1015) based upon the nationwide Danish Hernia Database collaboration. The response rate was 68.4%. Combined frequent and moderate or severe pain from the previous hernia site during activity was reported by 187 patients (18.4%). Pain during sexual activity was reported by 224 patients (22.1%), of which 68 (6.7%) had moderate or severe pain occurring every third time or more. Genital or ejaculatory pain was found in 125 patients (12.3%), and 28 (2.8%) patients reported that the pain impaired their sexual activity to a moderate or severe degree. Pain during sexual activity and subsequent sexual dysfunction represent a clinically significant problem in about 3% of younger male patients with a previous inguinal herniorrhaphy. Intraoperative nerve damage and disposition to other chronic pain conditions are among the most likely pathogenic factors.

The effect of wound instillation of a novel purified capsaicin formulation on postherniotomy pain: A double-blind, randomized, placebo-controlled study

BACKGROUND: Acute postoperative pain is common after most surgical procedures. Despite the availability of many analgesic options, postoperative pain management is often unsatisfactory. Purified capsaicin (ALGRX 4975 98% pure) has demonstrated prolong inhibition of C-fiber function in in vitro, preclinical, and clinical studies, and may be an effective adjunct to postoperative pain management. METHODS: We performed a single-center, randomized, double-blind, placebo-controlled study of the analgesic efficacy of a single intraoperative wound instillation of 1000 &mgr;g ultrapurified capsaicin (ALGRX 4975) after open mesh groin hernia repair in 41 adult male patients. The primary end-point was average daily visual analog scale (VAS) pain scores during the first week after surgery assessed as area under the curve (AUC). Pain was recorded twice daily in a pain diary for 4 wk. Physical examination and laboratory tests were done before and 1 wk after surgery, together with recordings of adverse events up to 28 days. Adverse events were recorded. Data were also analyzed using a mixed-effects analysis with NONMEM. RESULTS: VAS AUC was significantly lower during the first 3 days postoperatively (P < 0.05), but not for the whole 1 or 4 wk postoperatively. Mixed-effects analysis with NONMEM revealed that pain scores were significantly lower (P < 0.05) in the capsaicin group during the first 4 days. No clinically significant serious adverse events were observed, although a mild transient increase in liver enzymes was seen more often in the capsaicin-treated group. CONCLUSION: In the setting of a well-defined analgesic protocol standard, VAS AUC analysis and a mixed-effect analysis showed superior analgesia of capsaicin relative to placebo during the first 3–4 days after inguinal hernia repair.

The Effect of Mesh Removal and Selective Neurectomy on Persistent Postherniotomy Pain

Summary Background Data and Objective:Persistent pain affects everyday activities in 5% to 8% of patients after groin hernia repair. Because previous reports on the effect of neurectomy and/or mesh removal suffer from methodological problems we performed a detailed prospective trial of the effect of neurectomy and mesh removal on persistent postherniotomy pain. Methods:Twenty-one patients with postherniotomy pain >1 year, pain-related impairment of daily activities and a well-defined maximum pain localization where included. Inserted mesh was removed and a selective neurectomy was done in case of macroscopic nerve injury. The primary end point was changes in pain-related impairment of everyday activities assessed by the validated activities assessment scale before surgery and 6 months postoperatively. Quantitative sensory testing was used to evaluate sensory functions pre and postoperatively. Results:All patients completed the 6-month follow-up. There was a significant improvement in the activities assessment scale score for the whole group (preoperative vs. 6 months = 27 vs. 13 points, P = 0.004), despite 3 patients worsening. Quantitative sensory testing showed a significant postoperative increase in pressure pain detection threshold (P = 0.045) and cutaneous detection and pain thresholds (mechanical and warmth) (P < 0.03). Conclusions:Selective neurectomy and mesh removal may improve pain-related activity impairment in patients with persistent postherniotomy pain. Detailed neurophysiologic assessment is recommended to identify patients who may or may not benefit from reoperation and to allocate patients to specific surgical and/or medical intervention.

Heterogeneous sensory processing in persistent postherniotomy pain

&NA; Previous studies on sensory function in persistent postherniotomy pain (PPP) have only identified pressure pain threshold to be significantly different from pain‐free patients despite several patients reporting cutaneous pain and wind‐up phenomena. However the limited number of patients studied hinders evaluation of potential subgroups for further investigation and/or treatment allocation. Thus we used a standardized QST protocol to evaluate sensory functions in PPP and pain‐free control patients, to allow individual sensory characterization of pain patients from calculated Z‐values. Seventy PPP patients with pain related impairment of everyday activities were compared with normative data from 40 pain‐free postherniotomy patients operated >1 year previously. Z‐values showed a large variation in sensory disturbances ranging from pronounced detection hypoesthesia (Z = 6, cold) to pain hyperalgesia (Z = −8, pressure). Hyperalgesia for various modalities were found in 80% of patients, with pressure hyperalgesia in ˜65%, and cutaneous (mechanical or thermal) hyperalgesia in ˜35% of patients. The paradoxical combination of tactile hypoesthesia and hyperalgesia was seen in ˜25% of patients. Increased pain from repetitive tactile and/or brush stimulation was found in 51%, suggesting a role of altered central nociceptive function in this subpopulation. A high incidence (26%) of pressure hyperalgesia was found in the contralateral groin, with a significant correlation (rho = 0.58, p = 0.002) to the hyperalgesic level on the painful side, again suggesting central nervous mechanisms in PPP. In conclusion, this study shows that a standardized trauma results in heterogeneous combinations of hypo‐ and hyperalgesia. Z‐score evaluation of sensory function identifies subpopulations in PPP, which may be used in selecting surgical and/or pharmacological treatment strategies.

Ejaculatory pain: a specific postherniotomy pain syndrome?

Background: Sexual dysfunction due to ejaculatory and genital pain after groin hernia surgery may occur in approximately 2.5% of patients. However, the specific psychosexological and neurophysiologic characteristics have not been described, thereby precluding assessment of pathogenic mechanisms and treatment strategies. Methods: Ten patients with severe pain-related sexual dysfunction and ejaculatory pain were assessed in detail by quantitative sensory testing and interviewed by a psychologist specialized in evaluating sexual functional disorders and were compared with a control group of 20 patients with chronic pain after groin hernia repair but without sexual dysfunction, to identify sensory changes associated with ejaculatory pain. Results: Quantitative sensory testing showed significantly higher thermal and mechanical detection thresholds and lowered mechanical pain detection thresholds in both groups compared with the nonpainful side. Pressure pain detection threshold and tolerance were significantly lower in the ejaculatory pain group compared with the control group. ′The maximum pain was specifically located at the external inguinal annulus in all ejaculatory pain patients, but not in controls. The psychosexual interview revealed no major psychosexual disturbances and concluded that the pain was of somatic origin. All patients with ejaculatory pain had experienced major negative life changes and deterioration in their overall quality of life and sexual function as a result of the hernia operation. Conclusions: Postherniotomy ejaculatory pain and pain-related sexual dysfunction is a specific chronic pain state that may be caused by pathology involving the vas deferens and/or nerve damage. Therapeutic strategies should therefore include neuropathic pain treatment and/or surgical exploration.

Groin Hernia Repair: Anesthesia

The choice of anesthesia for groin hernia repair is between general, regional (epidural or spinal), and local anesthesia. Existing data from large consecutive patient series and randomized studies have shown local anesthesia to be the method of choice because it can be performed by the surgeon, does not necessarily require an attending anesthesiologist, translates into the shortest recovery (bypassing the postanesthesia care unit), has the lowest cost, and has the lowest postoperative morbidity regarding risk of urinary retention. Spinal anesthesia has no documented benefits for this small operation and should be avoided owing to the risk of rare neurologic side effects and the high risk of urinary retention. General anesthesia with short-acting agents may be a valid alternative when combined with local infiltration anesthesia, although an anesthesiologist is required. Despite sufficient scientific data to support the choice of anesthesia, large epidemiologic and nationwide information from databases show an undesirable high (about 10–20%) use of spinal anesthesia and low (about 10%) use of local infiltration anesthesia. Surgeons and anesthesiologists should therefore adjust their anesthesia practices to fit the available scientific evidence.

Challenges in postdischarge function and recovery: the case of fast-track hip and knee arthroplasty

This narrative review updates the recent advances in our understanding of the multifactorial pathogenesis for reduced postdischarge physical and cognitive function after fast-track surgery, using total hip and knee arthroplasty as surgical models. Relevant factors discussed include the surgical stress responses and potential methods for controlling postsurgical inflammation, pain, and cognitive dysfunction. The continuation of moderate to severe pain in up to 30% of patients for 2-4 weeks calls for better understanding of the underlying mechanisms and development of effective multimodal opioid-sparing analgesic regimens. The need for the development of effective physiotherapy programmes on a patient-specific basis is discussed, along with the need for optimal assessment of postoperative function to guide rehabilitation. Other relevant factors discussed include the role of orthostatic intolerance, sleep disturbances, and blood management, and specific patient populations at risk for adverse outcomes, including psychiatric disorders, to identify and guide future interventions for optimizing functional postdischarge outcomes after fast-track surgery.