From acute to chronic pain after thoracic surgery: the significance of different components of the acute pain response

Purpose: Acute postoperative pain is a strong predictor for postthoracotomy pain syndrome (PTPS), but the mechanism is unknown. Even though thoracic pain is usually considered the dominating acute pain after thoracic surgery, up to 45% of patients consider shoulder pain to be dominating pain and often this shoulder pain is referred visceral pain. This study aims to examine which components of the acute pain response after thoracic surgery were associated with PTPS and if any signs of a generalized central hypersensitivity could be identified in patients with PTPS. Patients and methods: In a prospective cohort study, 60 consecutive patients for lobectomy were included and examined preoperatively and 12 months postoperatively for pain and signs of hypersensitivity using a comprehensive protocol for quantitative sensory testing. Thoracic pain, shoulder pain, referred pain, and overall pain were assessed five times daily during the first four postoperative days. Results: Sixteen patients (31% of the 52 patients who completed the study) developed PTPS. Thoracic pain was the only pain component that was associated with PTPS and was a stronger predictor for PTPS than overall pain. There were no signs of hypersensitivity before or after the operation in patients with PTPS, but patients with PTPS more often suffered from preoperative pain. Conclusion: Thoracic pain was the only component of the acute pain response that predicted PTPS and was a stronger predictor than overall pain.