Mg Sulfate Versus Dexmedetomidine on Cerebral Oxygen Saturation

Inclusion Criteria: * Age from 21 to 60 years old. * either gender. * American Society of Anesthesiologists (ASA) physical status I and II. Exclusion Criteria: * Patient refusal to participate in research. * History of preoperative neuromuscular disease. * Patients with preexisting cerebral pathology (such as previous episodes of cerebral ischemia or stroke). * History of psychiatric illness. * History of orthostatic hypotension, myocardial infarction, uncontrolled hypertension or documented carotid stenosis. * Coagulopathy disorder. * Patients receiving magnesium supplementation. * Chronic use of opioids. * Current treatment with a β-blocker or calcium channel blocker.