Fever is common in critically ill neurosurgical patients, especially those with a prolonged length of stay in the ICU or a cranial disease. If hyperthermia worsens the functional outcome after a primary ischemic or traumatic injury, as has been suggested by several studies of stroke patients, treatment of fever is a clinical issue that requires better management.

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

The combined data suggest that coma at presentation has an independent and adverse effect on survival rates. Complete recanalization, distal clot location, and responsiveness at the time of presentation are statistically significant factors for increased patient survival rates.

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