**Table 5.**

*The Berlin grading system.*

blockers and antiepileptic medications should be continued until the day of the surgery. Angiotensin-converting enzyme inhibitors (ACEi) and angiotensin receptor blockers should be stopped a day before surgery. Patients with symptomatic MMD and vaso-occlusive disease of the carotid and coronary artery, are usually on antiplatelet medications. Continuation of low dose aspirin in the perioperative period varies from center to center. In some centers, aspirin is continued until the day of the surgery whereas clopidogrel and other antiplatelet are discontinued five to seven days before surgery and bridged with low molecular weight heparin [9, 11]. Premedication with anxiolytics may be beneficial in pediatric patients, as crying causes hyperventilation that results in hypocarbia and hence, cerebral vasoconstriction and cerebral ischemia [18, 19]. Careful titration of anxiolytics is vital to reduce anxiety and on the other hand, to reduce the risk of cerebral vasodilation caused by hypoventilation and hypercarbia, as it may lead to raised intracranial pressure and cerebral hemorrhage. Adequate hydration during the preoperative period is deemed necessary to avoid compromised cerebral blood flow.
