Postsurgical pain is now known to be one of the most common and difficult-to-treat complications of surgery. severe postoperative pain can significantly impair patients' quality of life, social functioning and contribute to excessive health care expenditures. It is worth noting that acute postoperative pain may play a vital role in central sensitization and up-regulation of pain receptors, even factors implicated in the development of CPSP. According to previous studies, the incidence of postoperative pain among patients undergoing spinal surgery was nearly 80%. At the same time, perioperative pain management of patients undergoing spinal surgery has not been clearly. For the past few years, pregabalin and esketamine are becoming important roles in perioperative pain management, lots of studies have shown that these two analgesics might relieve postoperative pain. The aim of this study was to evaluate the acute analgesic effects of esketamine and pregabalin in combination after spinal cord neoplasms resection, so as to find a better way to help the patients undergoing spinal surgery keep away from the acute perioperative pain.

Inclusion Criteria:

• Patient undergoing elective spinal cord neoplasms resection;
• Ages between 18 and 65 years old;
• American Society of Anaesthesiology (ASA) status I-III;
• Signed informed consent.

Exclusion Criteria:

• Previous adverse reaction to ketamine, s-ketamine or pregabalin;
• Patients with a diagnosed history of severe chronic pain;
• Patients with long-term analgesic treatment(gabapentin/opioids/ketamine);
• Patients with aphasia or inability to cooperate with the pain assessments;
• Known sever insufficiency of vitals(such as heart failure/renal dysfunction/hepatic failure);
• Patients with a diagnosed history of psychiatric disorder;
• Patients treated with gabapentin/pregabalin in the last three months;
• Drug abuse;
• Body mass index (BMI) > 35 kg/m2 ;
• Pregnancy or lactation.