The study aims to assess the interfacial plane blocks' effect on pain level, course of postoperative rehabilitation, and anti-inflammatory analgesic effect.

This study evaluates the analgesic efficacy in adults of bilevel, bilateral erector spinae plane (ESP) blocks after posterior cervical spinal fusion surgery by assessing postoperative pain scores and opiate requirements as the primary outcome measures. We aim to investigate how ESP blocks, performed under ultrasound guidance at the two vertebral levels, contribute to postoperative pain control. This will be determined by measuring numerical rating pain scores repeatedly following surgery and opiate consumption until the patient is discharged from the hospital. These primary outcome measures will be compared between a treatment group of participants receiving ESP blocks and a control group receiving a sham block. Our primary hypothesis is that ESP blocks significantly reduce postoperative pain and opiate requirements.

Inclusion Criteria:

• patients undergoing primary posterior cervical decompression and stabilization with instrumentation involving multi-levels in the cervical region,
• aged >18 years and <100 years
• ASA physical status 1, 2 or 3.

Exclusion Criteria:

• refuse to participate,
• history of opioid abuse,
• infection of the puncture site,
• aged <18 years and >100 years
• ASA 4 and 5