The incidence of perioperative stroke is related to the underlying risk factors of the patient and the risk factors associated with the procedure. The incidence of perioperative stroke is highest for cardiac, thoracic aortic, and vascular neurosurgery. The risk increases for neck surgery; while the risk is lowest for general surgery. The incidence of stroke in cardiac surgery is 1-5% and increases to more than 7% in older patients. The incidence of stroke is similar with or without extracorporeal circulation. Several patient-specific risk factors further increase the risk. goldstein et al. reported the incidence of stroke after thoracic aortic surgery. Apparently, there is an increased incidence of emergency surgery. Fan Zhiyi, Department of Anesthesiology, Peking University Cancer Hospital The incidence of stroke after carotid endarterectomy (CEA) is 3-5%. Naylor et al. reviewed and summarized data from two multicenter studies.11 Bond et al.12 reported that the increased incidence of stroke depends on the degree of carotid artery stenosis. The incidence of moderate stenosis is highest and the cause is unclear. Other factors that increase the incidence of stroke after CEA include: female, age >75 years, symptoms of total cerebral ischemia (relatively unilateral ischemia), systolic hypertension, and peripheral vascular disease. Heyer et al15 reported an association between cognitive dysfunction and apolipoprotein E monopeptide nucleotide polymorphisms after CEA, suggesting the role of genetic polymorphisms in post-CEA importance of ischemic injury. Patient-specific risk factors for stroke after cardiac surgery Aortic arch atheromatous plaque Renal insufficiency Recent infarction Prior stroke Carotid artery disease Hypertension Age >75 years Left ventricular insufficiency Low cardiac output Atrial fibrillation Possible mechanisms of perioperative stroke Intraoperative Postoperative Hypotension Hypotension Anemia Embolism: myocardial infarction, subacute endocarditis, patent foramen ovale Hypoxic hypercoagulable state Hypocapnia Atrial fibrillation Hypercapnia Anemia anemia hypoglycemia medically induced erythrocytosis hypercoagulable state hypoxia head position hypertension hypertension Through a review of the literature, Thompson et al16 reported that neck surgery was an important risk factor for stroke with a prevalence of 4.8%. However, they found an incidence of only 0.2% in their own case. Nonetheless, the unexpectedly high incidence of stroke after neck surgery raises the speculation that excessive rotation or extension of the patient’s head may be a vascular risk factor for perioperative stroke. This assumption was confirmed by an MRI study of the head position described above, a transcranial Doppler ultrasound study showing that head hyperextension may lead to decreased cerebral blood flow, and a case report of brainstem evoked potentials and a beauty salon stroke syndrome supporting this view. In salon stroke syndrome, symptoms of vertebrobasilar ischemia are associated with head hyperextension during hair washing in the salon. Lanska and Kryscio reported a 0.01% incidence of stroke in the postpartum period. Such strokes may be due to venous thrombosis. Risk factors include cesarean section, water-electrolyte abnormalities, hypertension, and infection. Ogilvy et al. reported a perioperative stroke incidence of 5-25% for cerebral aneurysm surgery (overall incidence 5.2%). However, if intraoperative arterial rupture occurs, the incidence rises to 38%. The increased risk of stroke is also associated with a prolonged temporary blockage of the proximal blood supplying artery to the aneurysm. Parikh and Cohen reviewed nearly 25,000 general surgery cases and found a stroke rate of 0.08%. 84% of strokes occurred within 7 days of surgery and the perioperative stroke-related morbidity and mortality rate was 26%. The authors concluded that most of these strokes were likely to be of embolic origin. They determined preoperative hypertension, preoperative neurologic symptoms, smoking, and abnormal ECG rhythms, particularly atrial fibrillation, as risk factors for stroke. Notably, they failed to confirm an association between preoperative carotid murmur and perioperative stroke. The importance of preoperative neurological symptoms was considered by Landercasper et al. and Larsen et al. who both reported an incidence of stroke in this group of patients after general surgery of approximately 2%, almost a 10-fold increase in risk. By comparing 61 cases of stroke after general surgery with controls who did not have perioperative stroke, Limburg and Wijdicks26 also found preoperative neurovascular disease to be an important risk factor. These observations focused on the anatomical and circulatory pathological alterations in patients with a history of stroke or transient cerebral ischemia. In addition, Limburg and Wijdicks found peripheral vascular disease and chronic obstructive pulmonary disease to be important risk factors. They failed to demonstrate an association between perioperative hypotension and stroke.