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Background and Purpose: We studied six patients suffering from pure, unilateral brain stem infarction to explore the association of remote cerebral and cerebellar blood flow changes with damage at different sites of this region of the brain.Methods: We used single-photon emission computed tomography and llliodoamphetamine to measure regional differences in tracer uptake. Qualitative image analysis and calculated asymmetry indexes were correlated to the location of the infarcted area on magnetic resonance imaging and to the patients' clinical findings.Results: Significant perfusion asymmetries were noted in the two patients with infarction in the upper pons but not in those with lesions below this level. They comprised a contralateral cerebellar and ipsilateral supratentorial hypoactivity that was most marked in the frontoparietal cortex. There was no clear relation between the patterns of cerebral or cerebellar tracer uptake and specific neurological findings.Conclusions: Remote perfusion changes after pure brain stem infarction may be seen both infratentorially and supratentorially and depend on the lesion site rather than on the neurological deficit. In this context, our study confirmed damage to the corticopontocerebellar pathways as the key event in the genesis of a crossed cerebellar diaschisis. The exact mechanisms causing ipsilateral cerebral hemispheric diaschisis await further clarification. (Stroke 1993;24:1162-1166

High levels of plasma fibrinogen in cerebrovascular disease cause deterioration in the hemorheologic pattern, microcirculation and cerebral perfusion. We compared the value of hepa-rin-induced extracorporeal LDL precipitation (HELP) which is a method that safely and effectively reduces plasma fibrinogen and lipoproteins and so improves the hemorheologic pattern and blood flow properties. Regional cerebral blood flow (rCBF) was measured by the ¹³³Xe SPECT clearance method. After first measuring rCBF, 15 patients suffering from cerebral multi-infarct disease underwent a single HELP application. One hour later a second measurement of rCBF was performed. Fifteen other patients with similar clinical symptoms and findings on CAT scans who were not subjected to HELP served as controls. The HELP treatment produced an immediate and statistically significant reduction of all parameters relevant to hemorheology, such as plasma fibrinogen, whole blood viscosity at both high and low shear rate, plasma viscosity, and red cell transit time. Total cholesterol, low density lipo-protein, and triglycerides were also reduced. The treated group showed 9.7-19.9% increased rCBF in different vascular regions examined relative to the untreated controls. The results obtained indicate that HELP has a potent effect in a situation demanding rapid and significant improvement of the blood flow.

Adverse hemorheologic effects induced by erythropoietin (EPO) treatment of renal anemia may pose a cerebrovascular risk. We therefore investigated the changes in cerebral perfusion, cerebral blood flow velocity (BFV) and neuropsychologic performance in 11 patients (mean age 37 years) receiving EPO. In response to EPO there was a significant (p < 0.01) increase in hematocrit (35%), hemoglobin (43%) and whole-blood viscosity (50% at high and 90% at low shear rate). The initially increased blood flow velocity dropped significantly (p < 0.05) and returned toward normal values in the middle cerebral arteries and the basilar artery (22 and 19% decrease, respectively). Global cerebral blood flow (CBF) decreased by 10% (not significant). The score of the Wechsler Adult Intelligence Scale digit symbol test improved significantly (p < 0.01) after EPO treatment. None of the patients developed cerebrovascular symptoms or side effects. We conclude that the hematologic and rheologic changes following EPO treatment cause CBF and BFV to return toward normal and improve neuropsychologic performance in patients with end-stage renal disease.

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