Serratus Posterior Superior Intercostal Plane Block Versus Intrathecal Morphine in VATS

Inclusion Criteria: * Age between 18 and 75 years * American Society of Anesthesiologists physical status I to III * Scheduled for elective video-assisted thoracoscopic surgery, including wedge resection, segmentectomy, or lobectomy Exclusion Criteria: * Refusal to participate * Pregnancy * Morbid obesity (body mass index greater than 40 kg per square meter) * Allergy to study medications * Neuropsychiatric disorders, cognitive impairment, or inability to communicate * History of substance abuse * Active systemic infection or infection at the planned injection site * Severe cardiac, respiratory, hepatic, renal, or endocrine disease. * Chronic pain syndrome or ongoing chronic pain treatment * Emergency surgery or previous ipsilateral VATS or thoracotomy * Preoperative opioid use: ≥15 mg oral morphine equivalents/day for ≥30 days within the previous 3 months. * Anticipated need for postoperative mechanical ventilation. * Contraindications to neuraxial or peripheral regional anesthesia, including anticoagulant therapy, coagulopathy, infection, or relevant anatomical abnormalities.