Brain damage after coronary artery bypass grafting.
BACKGROUND
Coronary artery bypass grafting (CABG) is associated with a risk for focal neurological deficits and neuropsychological impairment postoperatively.


OBJECTIVE
To examine the brain damage after CABG using diffusion-weighted magnetic resonance imaging and (1)H-magnetic resonance spectroscopy (MRS) and to correlate the results with neurological and neuropsychological findings.


METHODS
Thirty-five consecutive patients undergoing elective CABG were included. Patients underwent a neurological and neuropsychological examination before and after CABG. The magnetic resonance protocol was applied before and after (mean, 3 days) surgery and included a diffusion-weighted sequence and single-voxel MRS measurements in the frontal lobes.


RESULTS
None of the patients revealed a new focal neurological deficit after surgery. Diffusion-weighted magnetic resonance imaging demonstrated new ischemic lesions in 9 (26%) of the patients. The presence of an ischemic lesion was not related to impaired postoperative test performance (P>.50). The apparent diffusion coefficient values in the cerebellum and the centrum semiovale exhibited an increase after surgery (P<.01), consistent with vasogenic edema. Following surgery, MRS revealed a significant decrease in the metabolite ratio of N-acetylaspartate-creatine (mean +/- SD, 1.69 +/- 0.20 vs 1.52 +/- 0.19; P<.001). The extent of deterioration in neuropsychological test performance after surgery was closely related to the degree of the N-acetylaspartate-creatine ratio decrease (P<.01). A follow-up MRS scan revealed a normalization of the N-acetylaspartate-creatine ratio, which accompanied the recovery in psychological test performance.


CONCLUSIONS
Postoperative impairment in neuropsychological test performance is associated with a transient metabolic neuronal disturbance. Focal ischemic lesions after CABG are more frequent than the apparent neurological complication rate; however, they are not related to the diffuse postoperative encephalopathy.
Bendszus
Martin
M
Department of Neuroradiology, University of Würzburg, Josef-Schneider-Strausse 11, D-97080 Würzburg, Germany. bendszus@neuroradiologie.uni-wuerzburg.de
Reents
Wilko
W
Franke
Dorothea
D
Müllges
Wolfgang
W
Babin-Ebell
Jörg
J
Koltzenburg
Martin
M
Warmuth-Metz
Monika
M
Solymosi
Laszlo
L
D000368:Aged; D000768:Anesthesia, General / Q000009:adverse effects; D001921:Brain / Q000473:pathology*; D020520:Brain Infarction / Q000150:complications* / Q000175:diagnosis* / Q000209:etiology / Q000473:pathology / Q000523:psychology; D002315:Cardiopulmonary Bypass / Q000009:adverse effects; D003072:Cognition Disorders / Q000209:etiology / Q000473:pathology* / Q000523:psychology; D001026:Coronary Artery Bypass / Q000009:adverse effects* / Q000379:methods; D017558:Elective Surgical Procedures; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests