Background and Purpose Stroke is a potentially devastating complication of cardiac surgery. Identifying predictors of radiographic infarct may lead to improved stroke prevention for surgical patients. Methods We reviewed 129 post-operative brain MRIs from a prospective study of patients undergoing surgical aortic valve replacement (AVR). Acute infarcts were classified as watershed or embolic using pre-specified criteria. Results Acute infarct on MRI was seen in 79 of 129 patients (61%), interrater reliability for stroke etiology was high (κ =0.93). Embolic infarcts only were identified in 60 (46%), watershed only in 2 (2%), and both in 17 (13%). In multivariable logistic regression, embolic infarct was associated with aortic arch atheroma (OR=3.4, 95%CI 1.0-12.0, p=0.055), old subcortical infarcts (OR= 5.5, 95%CI 1.1-26.6, p=0.04), no history of PTCA or CABG (OR=4.0, 95%CI 1.2-13.7, p=0.03), and higher aortic valve gradient (OR=1.3 per 5mmHg, 95%CI 1.09-1.6, p=0.004). Watershed infarct was associated with internal carotid artery stenosis ≥70% (OR=11.7, 95%CI 1.8-76.8, p=0.01) and increased left ventricular ejection fraction (OR=1.6 per 5% increase, 95%CI 1.08-2.4, p=0.02). Conclusions The principal mechanism of acute cerebral infarction after AVR is embolism. There are distinct factors associated with watershed and embolic infarct, some of which may be modifiable.

The data suggest a progressive and delayed hypercoagulable state observed days after initial TBI. The hypercoagulable state may reflect excess platelet activity.

Teaching NeuroImages: Crossed cerebellar diaschisis in hemispheric status epilepticus A 36-year-old woman with Sheehan syndrome was found unresponsive. Evaluation was consistent with Addisonian crisis and myxedema coma. Continuous EEG demonstrated right frontotemporal nonconvulsive status initially refractory to multiple antiepileptic drugs (figure 1). MRI brain revealed restricted diffusion (figure 2) within the cortex of the right hemisphere and left cerebellum, suggestive of focal status epilepticus. There was no associated enhancement on apparent diffusion coefficient (ADC) (figure 2), and near normalization of ADC mapping on follow-up imaging. Although primarily recognized in the stroke literature, crossed cerebellar diaschisis may represent injury caused by excessive neuronal transmission from prolonged excitatory synaptic activity via the cortico-pontine-cerebellar pathways. 1,2

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