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BACKGROUND: Severe, persistent inguinal postherniorrhaphy pain (PIPP) is a debilitating condition that develops in 2-5% of patients. PIPP may be neuropathic in nature, yet the lesion in the peripheral nervous system has not been located. Most PIPP-patients demonstrate a tender point (TP) in the medial aspect of the inguinal region that triggers pain upon minimal pressure. As TPs may play a role in the pathophysiology of PIPP, the aim of this trial was to investigate the analgesic effects of local anaesthetic TP-blockade.METHODS: A randomized, double-blind, placebo-controlled, crossover trial was performed in 14 PIPP-patients and six healthy volunteers. All participated in two sessions, seven days apart, receiving 10 ml of 0.25% bupivacaine or normal saline via an ultrasound-guided fascial plane block at the TP. The TP-area was used for pain assessments (at rest, on movement, with 100 kPa pressure-algometry) and quantitative sensory testing (pressure pain thresholds, thermal detection/pain thresholds, supra-threshold heat perception), before and after the TP-blockade.RESULTS: The median (95% CI) reduction in pain was 63% (44.1 to 73.6%) after bupivacaine compared with 36% (11.6 to 49.7%; P=0.003) after placebo. Significant increases in cool detection (P=0.01) and pressure pain thresholds (P=0.009) with decreases in supra-threshold heat pain perception (P=0.003) were seen after bupivacaine only. In four out of six volunteers, increased thermal and evoked-pain thresholds after bupivacaine compared with placebo, was demonstrated.CONCLUSIONS: This trial demonstrates that peripheral afferent input from the TP-area is important for maintenance of spontaneous and evoked pain in PIPP.CLINICAL TRIAL REGISTRATION: NCT02065219.

BACKGROUND: The risk of persistent postsurgical pain (PPP) and subsequent pain-related functional impairment may potentially be reduced by video-assisted thoracic surgery (VATS) compared to thoracotomy. The aim of the study was therefore to assess in detail the incidence and consequences on activities of daily living of PPP after VATS.METHODS: Using a prospective observational design, 47 patients undergoing VATS completed both preoperative, early postoperative and 3 months follow-up. Preoperative pain, pain characteristics, psychological factors, pain-related functional impairment and quantitative sensory testing (QST) including nociceptive thresholds were compared with postoperative data.RESULTS: Only five (11%) patients developed PPP with NRS > 3 originating from the surgical area. However, about 30% of patients still reported some pain-related functional impairment from the surgical area within four well-defined domains of everyday activities. Psychological and sensory thermal tests did not predict persistent postoperative pain, except preoperative pin-prick sensitivity was higher in patients with PPP. Postoperative pain 7 days after surgery was significantly higher in PPP patients. Preoperative pain originating from remote areas did not predict PPP.CONCLUSION: The incidence of PPP, nerve damage (based on QST) and pain-related functional impairment following VATS was lower than reported following thoracotomy. No psychological or other factors predicted PPP. These findings call for further large-scale studies to support VATS to decrease PPP.

BACKGROUND: It is well known that chest drains are associated with severe movement-related acute pain. These noxious stimuli could play a significant role in development and maintenance of persistent post-operative pain. Therefore we studied chest drain sites in post-thoracotomy pain syndrome (PTPS) patients, in regard to pain and sensory dysfunction. METHODS: We quantified thermal and pressure thresholds on both the chest drain side and the contralateral side in 11 PTPS patients and 10 pain-free post-thoracotomy patients 33 months after the thoracotomy. On average, each patient had two chest drains inserted during surgery. RESULTS: At follow up, two patients experienced pain at the chest drain sites, but had maximal pain near or at the thoracotomy scar. Comparison between chest drain side and control side for all 21 patients demonstrated significantly elevated thresholds for warmth detection and heat pain on the chest drain side (P