Perioperative Quantitative Sensory Testing and Incision Pain Mapping in Thoracic Surgery

Perioperative Pain Phenotyping and Incision Pain Mapping Using Quantitative Sensory Testing in Patients Undergoing Thoracoscopic or Robotic-assisted Lung Resection: A Prospective Observational Pilot Cohort Study

Postoperative pain remains a common and clinically important burden after thoracic surgery and may progress to chronic postsurgical pain. Conventional pain assessment mainly relies on patient-reported pain intensity and analgesic consumption, which may not fully capture peri-incisional sensory abnormalities, mechanical hyperalgesia, or central sensitization.

This prospective observational pilot cohort study aims to evaluate the feasibility and acceptability of perioperative quantitative sensory testing (QST) and incision pain mapping in adult patients undergoing elective thoracoscopic or robotic-assisted lung resection. Participants will undergo baseline assessment before surgery, serial postoperative pain assessments during the first 72 hours, QST and mechanical hyperalgesia pain mapping at 48-72 hours after surgery, and follow-up assessments at discharge, 1 month, and 3 months after surgery.

The primary feasibility outcomes include recruitment rate, QST completion rates, follow-up completion rates, QST-related discontinuation rate, study-related adverse events, and data completeness. The main clinical mechanistic outcome is the area of peri-incisional mechanical hyperalgesia at 48-72 hours after surgery. Secondary outcomes include acute postoperative pain intensity, pain burden over 72 hours, opioid consumption, quality of recovery, QST changes, pain-map characteristics, and chronic postsurgical pain at 3 months.

This study will not assign or modify therapeutic interventions. All anesthetic, surgical, and analgesic management will be determined by the routine clinical care team. The study is expected to provide feasibility data, preliminary effect estimates, and mechanistic information for future larger perioperative pain studies.

This is a single-center, prospective, observational pilot cohort study conducted in adult patients scheduled to undergo elective thoracoscopic or robotic-assisted lung resection. The study is designed to characterize perioperative pain phenotypes using standardized quantitative sensory testing (QST), incision-centered mechanical hyperalgesia pain mapping, serial pain intensity assessments, analgesic exposure, psychological and sleep-related questionnaires, and exploratory inflammatory or plasma biomarker measurements.

Eligible participants will provide written informed consent before surgery. Baseline assessments will be performed 1-3 days before surgery and will include demographic and clinical data collection, baseline pain history, psychological and sleep-related questionnaires, preoperative QST, and blood sampling. QST will assess sensory function in the surgical-side thoracic region, contralateral mirror region, and a remote control site where applicable.

During the first 72 hours after surgery, resting and movement-related numeric rating scale pain scores will be collected at prespecified time points, together with perioperative anesthetic, regional block, surgical, analgesic, and recovery-related information. Opioid consumption will be converted to morphine milligram equivalents.

At 48-72 hours after surgery, participants will undergo core postoperative QST and incision-centered mechanical pain mapping. The pain map will be generated around the incision or main port site in eight radial directions. Standardized mechanical stimulation will be applied from normal surrounding skin toward the incision, and boundary points will be marked when the participant reports a transition from normal sensation to increased pain, sharpness, burning, or abnormal discomfort. These boundary points will be connected to estimate the area of mechanical hyperalgesia.

Additional assessments will be performed before discharge, at 1 month, and at 90 ± 14 days after surgery. Follow-up assessments will evaluate persistent pain, pain intensity, pain interference, neuropathic pain features, QST changes, pain-map characteristics, quality of recovery, and exploratory blood biomarkers. Chronic postsurgical pain will be assessed at 3 months after surgery and defined as new or worsened pain related to the surgical area, persisting for at least 3 months after surgery, and not better explained by other causes.

The study will not assign any therapeutic intervention. Surgical technique, anesthetic management, regional analgesia, postoperative analgesia, chest tube management, and perioperative care will follow routine clinical practice. Key perioperative variables will be prospectively collected and considered as potential confounders in statistical analyses.

Inclusion Criteria:

1. Male
2. Scheduled to undergo elective thoracoscopic or robotic-assisted lung resection.
3. American Society of Anesthesiologists physical status I to III.
4. Able to understand and communicate adequately and to complete study questionnaires independently or with assistance from study staff.
5. Willing to undergo QST assessment, perioperative venous blood sampling, and postoperative follow-up.
6. Able and willing to provide written informed consent.

Exclusion Criteria:

1. Definite chronic chest wall, shoulder, back, or upper limb pain with an average 2. Numeric Rating Scale score of 3 or higher during the preceding week.

3. Definite painful neuropathic disease or long-term use of opioids or other analgesics for more than 2 weeks.

4. Peripheral neuropathy, spinal cord disease, or other neurological disease that may substantially interfere with interpretation of QST results.

5. Severe cognitive impairment, psychiatric disorder, communication disorder, or inability to complete questionnaires and QST assessments.

6. Active infection, active autoimmune disease, or other disease condition that may substantially affect inflammatory protein measurements.

7. Emergency surgery, conversion to open thoracotomy, extensive chest wall resection, or severe intraoperative complications.

8. Any condition that, in the opinion of the investigator, makes the participant unsuitable for continued participation in the study.