Erector Spinae Block Vs Ketamine-based Multimodal Analgesia Protocol in Lumber Decompressive Surgery

Inclusion Criteria: * American Society of Anesthesiologists (ASA) status of I-III * scheduled for open lumber decompression surgery for degenerative stenosis or trauma involving 1or 2 levels without fusion. Exclusion Criteria: * Refusal to participate * Contraindication for peripheral regional anesthesia such as infection and coagulopathy. * Inability to comprehend the Numeric Rating Scale (NRS) or Patients who has cognitive function impairment * Preoperative renal or hepatic insufficiency * History of Opioid abuse. * Allergy to any of the study drugs