A Simplified clinical algorithm for standardized surgical treatment of chronic pain after inguinal hernia repair: A quality assessment study

Is pain control for chronic neuropathic pain after inguinal hernia repair using endoscopic retroperitoneal neurectomy effective? A meta-analysis of 142 patients from 1995 to 2022

PURPOSE

Neuropathic pain is a complication after groin hernia surgery. Triple neurectomy of the iliohypogastric nerve, ilioinguinal nerve and genitofemoral nerve is an efficient treatment modality, with several surgical approaches. The minimally invasive endoscopic method to neurectomy was specifically investigated in this meta-analysis. Our aim is to determine the efficacy of this method in the treatment of chronic neuropathic pain posthernia repair surgery.

METHODS

A systematic review was conducted using four databases to search for the keywords ("endoscopic retroperitoneal neurectomy" and "laparoscopic retroperitoneal neurectomy"). The NCBI National Library of Medicine, Cochrane Library, MEDLINE Complete and BioMed Central were last searched on 26 May 2022. Randomised control trials and retrospective or prospective papers involving endoscopic retroperitoneal neurectomy operations after inguinal hernia repair were included. All other surgeries, procedures and study designs were excluded. The internal quality of included studies was assessed using the Newcastle-Ottawa Scale. The percentage of patients who had reduction in pain ("positive treatment outcome") was used to assess the procedure's effectiveness in each analysis.

RESULTS

Five comparable endoscopic retroperitoneal neurectomy studies with a total of 142 patients were analysed. Both the Wald test (Q (6) = 1.79, = .775) and the probability ratio test (Q (6) = 4.24, = .374) provide similar findings (0.000, 0.0% [0.0%; 78%]). The meta-analysis' key finding is that the intervention was up to 78% effective (95% confidence interval, 71%; 84%).

CONCLUSION

Endoscopic retroperitoneal neurectomy can be an effective treatment option for postoperative neuropathic pain relief following surgical hernia repair. Although there is limited reported experience with this technique, it may provide a clinical benefit to the patient. We recommend further prospective data and long-term follow-up studies be conducted to confirm and expand on these outcomes.

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.

Risks of therapeutic versus prophylactic neurectomies

INTRODUCTION

Neuralgia due to a peripheral nerve injury may result in chronic pain, requiring a therapeutic surgical neurectomy. Meanwhile, some neurectomies are performed prophylactically, such as during inguinal mesh removal. Outcomes and risks associated with neurectomies are largely unknown despite consensus panels recommending them.

METHODS

All patients who underwent neurectomy 2013-2020 were analyzed. Data collection included demographics, preoperative symptoms, and postoperative outcomes. Indications for neurectomy were categorized as "therapeutic" if the patient had preoperative neuralgia or "prophylactic" if neurectomy was deemed necessary intra-operatively.

RESULTS

66 patients underwent 80 operations and a total of 122 neurectomies. On average, 1.5 neurectomies were performed per operation. Therapeutic neurectomies were performed in 42 (64%) patients and prophylactic in 34 (52%). The most commonly transected nerve was the ilioinguinal nerve. Average preoperative pain score was 5.8/10. On paired analysis, there was a significant reduction in pain after prophylactic neurectomy (2.5 points, p = 0.002) but not after therapeutic neurectomy. None of the nerves transected prophylactically had postoperative neuralgia, whereas 35% of the nerves transected therapeutically resulted in persistent or recurrent neuralgia (p < 0.001). To treat this, 21% required only nerve blocks and 9% required ablation or reoperative neurectomy. Three patients had complex regional pain syndrome (CRPS), a severe complication; all three were diagnosed with chronic pain syndrome pre-operatively.

DISCUSSION

We demonstrate that prophylactic neurectomy is largely safe. In contrast, a therapeutic neurectomy had a 35% risk of persistent or recurrent neuralgia, 9% required additional ablative or reoperative neurectomy. Three patients advanced from chronic pain syndrome to CRPS. We recommend the decision to perform a neurectomy be judicious and selective, especially in patients with known chronic pain syndrome. Prior to planning surgical neurectomy, other less invasive modalities should be exhausted and patients should be aware of its risks.