That surgical injury can lead to chronic pain is now well established.^821294150 From these reviews and studies using a systematic collection of data, the estimated incidences of chronic pain after various procedures are: leg amputation about 60%, thoracotomy about 50%, breast surgery about 30%, cholecystectomy 10–20%, and inguinal herniorrhaphy about 10%. Predictive risk factors for chronic postoperative pain are: preoperative pain, repeat surgery, psychological vulnerability, workers compensation, a surgical approach with risk of nerve damage, moderate or severe intensity of acute postoperative pain, radiation therapy, neurotoxic chemotherapy, depression, neuroticism, and anxiety.²⁹⁴¹

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.

Background: Groin hernia repair is one of the most common operations performed globally, with more than 20 million procedures per year. The last guidelines on groin hernia management were published in 2018 by the HerniaSurge Group. The aim of this project was to assess new evidence and update the guidelines. The guideline is intended for general and abdominal wall surgeons treating adult patients with groin hernias. Method: A working group of 30 international groin hernia experts and all involved stakeholders was formed and examined all new literature on groin hernia management, available until April 2022. Articles were screened for eligibility and assessed according to GRADE methodologies. New evidence was included, and chapters were rewritten. Statements and recommendations were updated or newly formulated as necessary. Results: Ten chapters of the original HerniaSurge inguinal hernia guidelines were updated. In total, 39 new statements and 32 recommendations were formulated (16 strong recommendations). A modified Delphi method was used to reach consensus on all statements and recommendations among the groin hernia experts and at the European Hernia Society meeting in Manchester on October 21, 2022. Conclusion: The HerniaSurge Collaboration has updated the international guidelines for groin hernia management. The updated guidelines provide an overview of the best available evidence on groin hernia management and include evidence-based statements and recommendations for daily practice. Future guideline development will change according to emerging guideline methodology.

Background and Objectives The transversus abdominis plane (TAP) block is a widely used nerve block. However, basic block characteristics are poorly described. The purpose of this study was to assess the cutaneous sensory block area, muscle-relaxing effect, and block duration. Methods Sixteen healthy volunteers were randomized to receive an ultrasound-guided unilateral TAP block with 20 mL 7.5 mg/mL ropivacaine and placebo on the contralateral side. Measurements were performed at baseline and 90 minutes after performing the block. Cutaneous sensory block area was mapped and separated into a medial and lateral part by a vertical line through the anterior superior iliac spine. We measured muscle thickness of the 3 lateral abdominal muscle layers with ultrasound in the relaxed state and during maximal voluntary muscle contraction. The volunteers reported the duration of the sensory block and the abdominal muscle–relaxing effect. Results The lateral part of the cutaneous sensory block area was a median of 266 cm² (interquartile range, 191–310 cm²) and the medial part 76 cm² (interquartile range, 54–127 cm²). In all the volunteers, lateral wall muscle thickness decreased significantly by 9.2 mm (6.9–15.7 mm) during a maximal contraction. Sensory block and muscle-relaxing effect duration were 570 minutes (512–716 minutes) and 609 minutes (490–724 minutes), respectively. Conclusions Cutaneous sensory block area of the TAP block is predominantly located lateral to a vertical line through the anterior superior iliac spine. The distribution is nondermatomal and does not cross the midline. The muscle-relaxing effect is significant and consistent. The block duration is approximately 10 hours with large variation.

Inguinal herniotomy is one of the most frequent surgical procedures and chronic pain affecting everyday activities is reported in approximately 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.