Background and Purpose-The ischemic core and penumbra have not been thoroughly characterized after acute cerebral thromboembolic occlusion in humans. Differentiation between areas of potentially viable and irreversibly injured ischemic tissue may facilitate assessment and treatment of stroke patients. Methods-Cerebral blood flow (CBF) was measured in 20 patients with acute middle cerebral artery (MCA) occlusion between 60 and 360 minutes after stroke onset, with the stable xenon computerized tomography (CT) technique. Threshold displays were generated at a single level, and the percentages of hemisphere with CBF Յ6, Յ10, 11 to 20, 21 to 30, and Ͼ30 cm 3 ⅐ 100 g Ϫ1 ⅐ min Ϫ1 were measured. The corresponding images on 12 available follow-up CT scans were similarly assessed to determine the area of final infarct. Comparisons were analyzed with a paired Student's t test and Pearson's correlation coefficient. Results-Discrete and confluent areas of CBF Յ20 cm 3 ⅐ 100 g Ϫ1 ⅐ min Ϫ1 were identified in all patients, ipsilateral to the symptomatic MCA territory. The average area of CBF Յ20 cm 3 ⅐ 100 g Ϫ1 ⅐ min Ϫ1 within the ipsilateral hemisphere was 66Ϯ17% compared with 36Ϯ12% contralaterally (PϽ0.001). A difference in the extent of low CBF was due primarily to areas with CBF Յ10 cm 3 ⅐ 100 g Ϫ1 ⅐ min Ϫ1 (48Ϯ18% versus 16Ϯ7%, PϽ0.001). The area of most severe ipsilateral ischemia (Յ6 cm 3 ⅐ 100 g Ϫ1 ⅐ min Ϫ1 ) best corresponded to the final area of infarction (37Ϯ18% versus 40Ϯ24%; correlation coefficient, 0.866; PϽ0.01). The acute ischemic core destined to infarction was not surrounded by a widened rim of moderate ischemia because the area with CBF 11 to 20 cm 3 ⅐ 100 g Ϫ1 ⅐ min Ϫ1 was similar bilaterally (19Ϯ4% versus 20Ϯ7%, Pϭ0.792, thus not significant). Conclusions-Our study in acute human stroke involving MCA occlusion indicates that a severely ischemic core (CBF Յ6 cm 3 ⅐ 100 g Ϫ1 ⅐ min

Immunosuppressive-associated leukoencephalopathy is a significant complication of cyclosporine (CsA) or tacrolimus therapy. However, the precise time of onset, role of putative risk factors, differences, if any, in presentation in various types of organ transplantation and outcome of this entity, remain poorly defined. Fifty cases of immunosuppressive-associated leukoencephalopathy reported in the literature in organ transplant recipients, were reviewed. Of 50 cases, 31 occurred in liver, 8 in renal, 6 in lung, and 5 in heart transplant recipients. Median time to onset was 28 days (range 3-1512 days); 82% occurred within 90 days of transplantation. Lesions tended to occur earlier in the liver transplant recipients, compared with other organ transplant recipients (median 9 vs. 29 days, P=.19). Seizures 74%, altered mental status 50%, and visual abnormalities 28% were the most frequently presenting features. Ten percent of the patients had fever with no documented source of infection. Systemic hypertension (P=.001), and lesions in the presence of therapeutic drug levels (P=.11) were more likely to occur with CsA than tacrolimus. Neuroimaging and clinical abnormalities were reversible on cessation or reduction of CsA or tacrolimus in all but two cases. Resolution of neurologic signs/symptoms occurred a median of 4 days and neuroimaging abnormalities in a median of 20 days on reduction/cessation of the drug. Immunosuppressive-associated leukoencephalopathy is a unique entity that can usually be diagnosed on the basis of its distinctive time of onset, and clinical and neuroimaging characteristics, and it is potentially reversible if promptly diagnosed. Despite identical clinical presentation of this syndrome in the recipients of CsA and tacrolimus, above noted variations in risk factors suggest that a difference in pathophysiologic mechanism may exist.

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The semiautomated computer method of measuring tumor volume was faster than the manual trace method. Semiautomated computer approaches offer an alternative to manual tracing for measuring serial tumor volumes in patients with high-grade brain neoplasms.

Tacrolimus (FK506) has recently been approved for immunosuppression in organ transplantation, although its use is accompanied by a wide spectrum of neurotoxic side effects. We describe the clinical, radiological, and pathological features of 3 cases of tacrolimus-related leukoencephalopathy. The syndrome of immunosuppression-related leukoencephalopathy is proposed as an uncommon neurological syndrome occurring in patients with organ transplants involving demyelination, in particular in the parieto-occipital region and centrum semiovale. Although the syndrome is not associated with a particular (absolute) serum level of tacrolimus, it resolves spontaneously upon decreasing the dose. The tacrolimus-related syndrome has a similar radiographic and pathologic appearance as the analogous syndrome that occurs in patients taking cyclosporine.