Neurologic Complications in the Immediate Postoperative Period After Cardiac Surgery. Role of Brain Magnetic Resonance Imaging

Abstract

Neurologic complications still cause significant morbidity and mortality in the immediate postoperative period following cardiac surgery. Our understanding of the pathogenesis, prevention, and management of these lesions is constantly developing. We describe neurologic complications and their course in a cardiac surgery cohort and analyze the value of brain magnetic resonance imaging (MRI), using T1-weighted, T2-weighted, and FLAIR sequences, in patients with postoperative stroke or encephalopathy in whom CT scanning revealed no abnormalities explaining their clinical condition. In 688 patients studied postoperatively, we observed 57 neurologic complications (8.3%): 25 strokes, 24 encephalopathies, 5 seizure disorders, 2 brain deaths, and 1 intracranial hemorrhage. Initial CT scanning failed to show significant findings in 70%. 18 patients underwent brain MRI. In all but 1 of the 11 with stroke, MRI showed areas of acute or subacute infarction (i.e., hyperintensity in FLAIR or T2-weighted sequences) in different locations, mainly in a watershed distribution. In 3 of the 4 patients with mild-to-moderate encephalopathy, MRI showed lesions similar to those previously described for stroke. In the remaining 3 patients, who had severe encephalopathy, MRI showed diffuse cortical necrosis. The incidence of neurologic complications in the postoperative period following cardiac surgery is significant. In a high percentage of patients, brain CT scanning may not show pathologic findings. In selected patients, MRI could help identify areas of infarction not detected by CT. These images could improve clinicians' understanding of the pathogenic, pathophysiologic, clinical, and prognostic characteristics of such neurologic complications.