Chronic postsurgical pain has become one of the most common complications of surgery. The quality of life will be impacted once the postsurgical patients are combined with persistent pain. What's more, the postsurgical pain may increase other adverse outcomes. It's important to find a better way to keep the postsurgical patients away from postoperative pain. Esketamine and pregabalin have become potentially effective drugs on CPSP.

Inclusion Criteria:

• Patient undergoing elective primary spinal tumor surgery;
• 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.