General anesthesia has an important effect on inflammatory cytokines. Inhalational agents as isoflurane and sevoflurane attenuate immune function expressed by neutrophil chemoattractant-1 as well as inflammatory enzyme and also they reduce inflammatory cascade. Total intravenous anesthesia (TIVA) based on using propofol suppresses the inflammatory response caused by surgery to a greater extent because Propofol affects the balance between pro-inflammatory and anti-inflammatory cytokines, increasing production of the anti-inflammatory cytokine IL-10 and at the same time reducing the increase of IL-6 during the perioperative period. It also alters expression of nitric oxide and inhibits neutrophil function. TIVA has many advantages such as; fewer side effects, earlier discharge, better patient satisfaction, faster recovery, less nausea and vomiting and reduced muscle relaxant requirements. Paravertebral block has an important role in the inflammatory and immune response. The paravertebral block can decrease perioperative inflammation and prevent immune suppression. Also, it can attenuate the cytokine response and reduce acute stress response caused by surgery. Decrease inflammation processes, improve surgery result, limit the duration of hospital stay, decrease post-operative fatigue and reduce postoperative complications.

Spine surgery is characterized by an elevation in levels of the inflammatory cytokines such as interleukin IL-6, IL-1β, and IL-17. These cytokines promote chemokine production and changes in cell phenotype which lead to activation of T and B cells, macrophages, neutrophils, and mast cells further amplifying the inflammatory cascade. Different analgesic modalities are used for pain management during and after spine surgery as narcotic analgesics, nonsteroidal anti-inflammatory drugs, Paracetamol and neuraxial techniques like intrathecal drug administration, epidural analgesia and paravertebral block. In this study, Paravertebral Block is used as a new and recent analgesic strategy for spine surgery. It has the advantage of higher success rate and analgesic efficacy, less risk of neurological complications than most other regional anesthetic techniques, less nausea, vomiting, and constipation compared with opioid-based analgesic techniques, urinary retention does not occur, unlike neuraxial techniques and intense block of both the sympathetic and somatic nerves. This study will be conducted with the hypothesis that the addition of paravertebral block as an analgesic regimen with total intravenous anesthesia (propofol-based) will have a better Immunomodulatory effect in patients undergoing posterior lumbar spine fixation surgery.

Inclusion Criteria:

• patients scheduled for primary fixation of posterior lumbar spine surgery.
• American Society of Anesthesia statuses I or II patients.
• Single or double level lumbar spine fixation.
• Fixed surgical team.

Exclusion Criteria:

1. Patient refusal or uncooperative Patient.
2. History of allergy to any anesthetic agents will be used in the study.
3. Local sepsis.
4. Abnormal coagulation test results.
5. Usage of antiplatelet therapy.
6. Demyelinated neurological diseases as multiple sclerosis.
7. Mental retardation, psychotropic drug consumption.
8. Recurrent spine fixation.
9. Severe coronary or peripheral artery disease.
10. Severe cardiac disease, renal or hepatic failure.