A narrative review on the non-surgical treatment of chronic postoperative inguinal pain: a challenge for both surgeon and anaesthesiologist

Intravenous Ketamine Infusion for Managing Chronic Postoperative Pain After Inguinal Herniorrhaphy: A Case Report

Chronic postsurgical pain (CPSP) is a debilitating condition that affects up to 50% of patients after procedures like inguinal herniorrhaphy, significantly impairing quality of life. This case report describes a 63-year-old male who experienced refractory CPSP for 5 years following inguinal hernia repair. The patient reported persistent pain despite multiple pharmacological treatments, including amitriptyline, gabapentin, and codeine, as well as nerve blocks and nonpharmacological interventions like acupuncture. Periodic intravenous ketamine infusions (30 mg every 30 days) were introduced, resulting in substantial pain relief, improved mobility, and enhanced functionality. Ketamine, a noncompetitive NMDA receptor antagonist, has shown promise in modulating central sensitization in chronic pain, with minimal adverse effects at low doses. This case aligns with the 2018 consensus guidelines on ketamine use in chronic pain and contributes to the growing body of evidence supporting its efficacy in CPSP management. While this therapy demonstrated remarkable clinical benefits, further research is essential to establish optimal protocols and long-term outcomes for ketamine use in chronic postoperative pain.

Associations between (pharmaco-)genetic markers and postoperative pain after inguinal hernia repair - a prospective study protocol

BACKGROUND

Postoperative pain is a common complication following surgery, with severity and duration varying between patients. Chronic postoperative pain after inguinal hernia surgery has an incidence rate of approximately 10%. Risk factors for acute and chronic pain following hernia surgery include age, sex, psychosocial factors, and demographic background. Additionally, genetic polymorphisms in enzymes involved in pain mechanisms, as well as the metabolism of analgesics might influence pain perception, pain development, and response to pain medications. Key enzymes include the catechol-o-methyltransferase (COMT), the µ-opioid receptor 1 (OPRM1), and the cytochrome P450 2D6 (CYP2D6). CYP2D6 plays a crucial role in metabolizing analgesics such as tramadol, codeine, and oxycodone. It is also suspected to be involved in the synthesis of catecholamines and endogenous morphines suggesting a potential role in pathophysiology of pain. We hypothesize that the CYP2D6 activity influences the development of postoperative pain after hernia surgery.

METHODS

This study is a prospective, observational, multicenter association study investigating adult patients scheduled for inguinal hernia surgery using a robotic-assisted (rTAPP) approach. Patients are enrolled during the preoperative surgical consultation. A buccal swab is collected for genetic testing at this time. Pain at the site of the hernia is assessed using the validated EuraHSQoL score preoperatively and at 2, 4, and 6 weeks postoperatively. Additionally, information on co-medication and details of the surgery will be collected. The planned number of participants is 350 patients. The primary objective is to analyze the association between different genotype-predicted CYP2D6 phenotypes and patient-reported pain intensity 6 weeks after surgery. Secondary objectives include the association between further genetic variants, such as the COMT rs4680 and OPRM1 rs1799971 genotype, and pain severity. Additionally, the potential of pharmacogenetic panel testing to optimize analgesic therapy in hernia surgery patients will be explored.

DISCUSSION

The findings of this study are expected to provide valuable insights into identifying patients at higher risk for postoperative pain before surgery. This knowledge could pave the way for tailored interventions during and after surgery for these specific patients.

TRIAL REGISTRATION

Deutsches Register Klinischer Studien https://www.drks.de/DRKS00034796 Registered on August 07, 2024.

Anatomical Features in Inguinal-Pubic-Adductor Area That May Contribute to Gender Difference in Susceptibility to Groin Pain Syndrome

Groin pain syndrome (GPS) is often a diagnostic challenge for sport physicians. Despite this diagnostic difficulty, the incidence of GPS in athletes is relatively high, afflicting 10-20% of the total sports population. In the literature, a certain number of studies demonstrate an important gender-based difference in the incidence of GPS in both sexes, with a ratio of female:male athletes clearly in favor of the female gender being relatively less prone to GPS. Indeed, some anatomical differences between the two sexes seem to represent a protective factor against the onset of GPS in women, although the current literature still needs to clarify the validity of these findings. It is the aim of this systematic review to examine all the anatomical differences between men and women that may be responsible for the difference in the onset of GPS in the two sexes.

Quantitative somatosensory assessments in patients with persistent pain following groin hernia repair: A systematic review with a meta-analytical approach

OBJECTIVES

Quantitative sensory testing (QST) provides an assessment of cutaneous and deep tissue sensitivity and pain perception under normal and pathological settings. Approximately 2-4% of individuals undergoing groin hernia repair (GHR) develop severe persistent postsurgical pain (PPSP). The aims of this systematic review of PPSP-patients were (1) to retrieve and methodologically characterize the available QST literature and (2) to explore the role of QST in understanding mechanisms underlying PPSP following GHR.

METHODS

A systematic literature search was conducted from JAN-1992 to SEP-2022 in PubMed, EMBASE, and Google Scholar. For inclusion, studies had to report at least one QST-modality in patients with PPSP. Risk of bias assessment of the studies was conducted utilizing the Newcastle Ottawa Scale and Cochrane's Risk of Bias assessment tool 2.0. The review provided both a qualitative and quantitative analysis of the results. A random effects model was used for meta-analysis.

RESULTS

Twenty-five studies were included (5 randomized controlled trials, 20 non-randomized controlled trials). Overall, risk of bias was low. Compared with the contralateral side or controls, there were significant alterations in somatosensory function of the surgical site in PPSP-patients. Following thresholds were significantly increased: mechanical detection thresholds for punctate stimuli (mean difference (95% CI) 3.3 (1.6, 6.9) mN (P = 0.002)), warmth detection thresholds (3.2 (1.6, 4.7) °C (P = 0.0001)), cool detection thresholds (-3.2 (-4.9, -1.6) °C (P = 0.0001)), and heat pain thresholds (1.9 (1.1, 2.7) °C (P = 0.00001)). However, the pressure pain thresholds were significantly decreased (-76 (-123, -30) kPa (P = 0.001)).

CONCLUSION

Our review demonstrates a plethora of methods used regarding outcome assessments, data processing, and data interpretation. From a pathophysiological perspective, the most consistent findings were postsurgical cutaneous deafferentation and development of a pain generator in deeper connective tissues.

TRIAL REGISTRATION

CRD42022331750.