This study aims to compare the effects of the classical Total Intravenous Anesthesia (TIVA) method and multimodal anesthesia protocols created by adding lidocaine and ketamine infusions on postoperative pain management, opioid consumption, and surgical recovery in posterior thoracolumbar spinal fusion surgeries.

A prospective observational study was conducted with 72 patients undergoing posterior thoracolumbar spinal fusion surgeries. Patients were evenly divided into three groups: classical TIVA (propofol and remifentanil), TIVA + ketamine, and TIVA + lidocaine. Hemodynamic parameters and drug dosages were recorded during the intraoperative period, while pain scores, opioid consumption, time to first ambulation and bowel movement, as well as nausea-vomiting and sedation scores, were documented postoperatively.

Inclusion Criteria:

• Aged 18 years or older,
• ASA classification I-III
• Patients undergoing posterior thoracolumbar spinal surgery and neuromonitoring under general anesthesia

Exclusion Criteria:

• Emergency operations
• Pregnant patients
• Patients with ASA classification IV or higher*
• Patients allergic to morphine and local anesthetics
• Patients with neurological or psychiatric disorders (on ongoing antidepressant and/or anticonvulsant therapy) Illiterate patients
• Patients unable to cooperate
• Extremely low or high body weight (less than 40 kg or more than 100 kg)
• Chronic opioid use
• Diabetes mellitus (DM) requiring insulin therapy
• Chronic alcohol use
• Patients with peripheral neuropathy
• Patients with cardiac arrhythmias

Patients aged 18 years or older, classified as ASA I-III, undergoing posterior thoracolumbar spinal surgery and neuromonitoring under general anesthesia, and fluent in Turkish.