Quantitative sensory testing of persistent pain after video-assisted thoracic surgery lobectomy

Abstract

Background: Video-assisted thoracic surgery (VATS) lobectomy may potentially reduce the risk of post-thoracotomy pain syndrome (PTPS). However, it may still carry a risk of intraoperative nerve damage and thereby development of PTPS. Thus, our aim was to present a detailed long-term neurophysiological characterization of PTPS after VATS.

Methods: Quantitative sensory testing, using thermal and mechanical stimuli, was performed in 13 PTPS patients and 35 pain-free patients recruited 33 months after VATS lobectomy.

Results: When comparing the operated side with the control side in PTPS patients, increased thresholds of tactile and warmth detection were observed, while in pain-free patients, increased thresholds of warmth detection, cool detection, and heat pain were demonstrated. At the anterior porthole, pain-free patients displayed increased threshold to thermal detection when compared with the control side. Only side-to-side difference for tactile detection threshold was increased in PTPS patients compared with pain-free patients. Assessment of central sensitization showed no significant differences within or between PTPS and pain-free patients nor did group comparison of area of hypo- and hyperaesthesia to cool. Anxiety and depression scores (HADS) were higher in PTPS patients, but the area of hyper- and hypoaesthesia did not differ significantly between HADS groups.

Conclusions: Increased sensory thresholds suggest nerve injury to be present on the operated side in both PTPS and pain-free patients. However, no significant quantitative differences between PTPS and pain-free patients could be found, implicating the presence of factors other than intercostal nerve injury as important for development of PTPS after VATS lobectomy.