Neurotoxicity of Spinal Anesthesia With Ropivacaine and Bupivacaine

Consenting patients, scheduled for orthopaedic surgery under spinal anesthesia will be randomly assigned (1:1) to receive ropivacaine or bupivacaine as a single shot before the start of surgery, followed by bolus doses of the same local anesthetic as required during the surgery, and continuous infusion of the same local anesthetic for 24 hours postoperatively. Primary Outcome Measures: Evaluation of changes in concentrations of glutamate in the cerebrospinal fluid and in the blood. Secondary outcomes: : Evaluation of changes in concentrations of selected mediators of inflammatory response (IL-1β, IL-6, TNF and others) and selected chemokines as markers of the glia damage. Hemodynamic stability during the surgery, and efficacy of postoperative analgesia will be also evaluated.