Comparison of tizanidine and placebo on the postoperative pain after lumbar disc surgery.

Lumbar discectomy is a common elective surgical procedure. Many patientsexperience postoperative back pain which may delayhospital discharge. α2-agonist، inhibit pain sensation by inhibiting norepinephrine release from dorsal horn neuron in accordance with prolongation of analgesia and decreasing analgesic morphine requirements. The aim of this study was to assess the effect of tizanidine on the intensity of pain and equirement for analgesics for relief of postoperative pain after lumbar disc surgery. Eighty patients with single-level unilateral herniated disc that wererefractory to conservative management، and undergoing lumbar disc surgery under standard general anesthesia were enrolled. Forty patients received pre-operative oral Tizanidine and forty patients received placebo. Besides، all patients received patient controlled morphine pump for postoperation analgesia. Pain was measured usingnumerical rating scale (NRS) at 1، 3، 6، 12 and 24 hours post-operation. Total morphine requirement was also measured. Post-operative pain score (NRS) wassignificantly lower at 6 hour (p= 0. 01)، 12 (p= 0. 027) and 24 hours (p= 0. 015). Total 24 hours morphine requirement (rescue analgesic) was also significantly lower in Tizanidine than in control (p= 0. 02). Pre-operative use of tizanidine prior to lumbar disc herniation surgery maintains effective post-operative analgesia and decreases morphinerequirement without major or minor complications.