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Background and Purpose: The use of flow velocity changes in the middle cerebral artery (MCA) measured by Doppler techniques as an index of corresponding cerebral blood flow (CBF) changes is based on the assumption that the insonated arterial diameter remains stable. The postulate of unchanging vessel calibers during CBF changes, however, is still under debate. We performed simultaneous measurements of arterial and venous blood flow velocities by transcranial Doppler ultrasound during various stages of hypercapnia to analyze diameter changes in the insonated vessels by comparing differences in the vasomotor reactivity., Methods: Simultaneous Doppler recordings of 1 MCA and of a contralateral venous vessel thought to represent the sphenoparietal sinus (SPS) were carried out with a pair of 2-MHz range-gated transducers in 16 young healthy subjects during variations of end-tidal PaCO2., Results: During hypercapnia the mean blood flow velocity of the MCA rose from 62. 5+/-10.2 to a maximum of 99+/-12.2 cm/s (vasomotor reactivity of 60. 1+/-17.3%). The corresponding values in the SPS were significantly higher (P<0.001), revealing a rise from 17.8+/-5.7 to 34.9+/-14.3 cm/s (vasomotor reactivity of 91.4+/-25.9%). Exponential and linear regression analyses revealed an identical high correlation (r2=0.97 and 0.98 for the MCA and SPS, respectively). Slopes were 0.034+/-0. 01 on the arterial and 0.048+/-0.01 on the venous side. The CO2 reactivity (percentage per mm Hg, EtCO2) was found to be 4.5+/-1%/mm Hg in the MCA and 6.8+/-1.5%/mm Hg in the SPS. This difference indicates a vasodilation of the MCA in comparison to the venous vessel., Conclusions: We have demonstrated a different reaction pattern between intracranial venous and arterial vessels related to end-tidal CO2. Relating the flow velocities to the square of the vessel diameter and assuming a global rise of CBF and not extensible sinus walls, our results indicate that the MCA undergoes a vasodilation of 9.5+/-7% in maximal hypercapnia.

Background and Purpose: This study was performed to gather information about long-term prognosis after infratentorial transient ischemic attacks and minor strokes and about the factors influencing it., Methods: We included 226 patients with transient ischemia and 169 patients with a minor stroke of the brain stem/cerebellum consecutively admitted to a neurological department. Medical records and the findings of computed tomography, Doppler ultrasonography, and angiography were evaluated retrospectively. Follow-up information was gathered from the patients and their physicians by questionnaires. Complete follow-up information was available for 381 patients., Results: During a mean follow-up of 3.9 years, 15.7% of the 381 patients suffered a stroke and 6.8% a myocardial infarction; 15% died. Kaplan-Meier estimates revealed a cumulative stroke rate of 5.1% within the first year and a risk of stroke, myocardial infarction, or death of any cause of 9.8%. In a proportional hazards model, the time-dependent risk of stroke was significantly increased by increasing age (p = 0.018), minor stroke (p = 0.0005), hypertension (p = 0.022), previous stroke (p = 0.0006), and carotid artery occlusive disease (p = 0.0065). The probability of stroke, myocardial infarction, or death was influenced by age (p = 0.0001), minor stroke (p = 0.006), diabetes (p = 0.015), previous stroke (p = 0.002), infarct on a computed tomogram (p = 0.041), and carotid artery disease (p = 0.032)., Conclusions: Long-term prognosis after brain stem/cerebellar transient ischemic attacks and minor strokes is significantly influenced by age, diabetes, hypertension, previous stroke, and concomitant carotid artery disease. Patients with transient ischemic attacks have a better prognosis than those with minor stroke.

The extent of edema related to infarction assessed by computed tomography was compared with the CSF-lactate concentration in patients with middle cerebral artery (MCA) infarction on the first, third and seventh day following the stroke. A linear correlation between the extent of infarction edema and CSF-lactate level was most distinct on the third day. CSF-lactate concentration on the third day can be considered as a measure of the extent of the accompanying edema which in our study reached its maximum at this time in comparison to the first and seventh day.