Cerebral bloodflow and oxygen metabolism in borderzone and territorial infarcts due to symptomatic carotid artery occlusion

Detecting misery perfusion in unilateral steno-occlusive disease of the internal carotid artery or middle cerebral artery by MR imaging

BACKGROUND AND PURPOSE

Elevated OEF is a surrogate for misery perfusion. Our aim was to detect misery perfusion in patients with unilateral steno-occlusive disease of the ICA or MCA by using T2*-based MR imaging and to determine the relationship between brain ischemia and OEF.

MATERIALS AND METHODS

Twenty-three patients with unilateral steno-occlusive disease of the ICA or MCA and 8 healthy volunteers were included in this study. Hemodynamic information was obtained in all subjects by MR imaging. Three regions of interest were placed in the anterior, middle, and posterior parts of the brain bilaterally to measure the OEF and CBF values. The OEFs of the regions of interest in the hemispheres ipsilateral and contralateral to the vascular lesions were compared. Brain regions with OEF greater than that in controls were determined as misery perfusion in patients. The association of vascular lesions, rCBF, and the presence of territory infarction with elevated OEF was investigated.

RESULTS

There was a statistically significant difference in OEF between the ipsilateral and contralateral hemispheres in the patients (t = 3.632, P = .001). Fourteen regions of interest with misery perfusion were determined in the ipsilateral hemispheres, while 3 regions with elevated OEFs were found in the contralateral hemispheres. In the ipsilateral hemispheres, decreased rCBF was associated with elevated OEF (r = -0.451, P < .001). Patients with territory infarction had more regions of interest with misery perfusion than patients without territory infarction (χ(2) = 3.889, P = .049).

CONCLUSIONS

By using the MR imaging technique, misery perfusion demonstrated as elevated OEF was detected in patients with severe atherosclerotic ICA or MCA disease. Identification of misery perfusion with MR imaging may be helpful in the evaluation of brain ischemia.

Internal and cortical border-zone infarction: clinical and diffusion-weighted imaging features

BACKGROUND AND PURPOSE

The pathogenesis of internal border-zone (IBZ) and cortical border-zone (CBZ) infarcts is unclear. Both types of infarct have been combined into a single group in most previous reports, which has produced conflicting results. We hypothesized that different pathogenic mechanisms underlie IBZ and CBZ infarcts.

METHODS

We reviewed 946 consecutive patients with ischemic stroke within the middle cerebral artery territory. IBZ and CBZ infarcts were selected based on diffusion-weighted imaging templates to identify vascular territories. Baseline patient characteristics, clinical courses, and neuroradiological features were compared between patients with IBZ and CBZ infarcts.

RESULTS

We identified 45 IBZ and 75 CBZ infarct patients. Compared with the CBZ infarct patients, IBZ infarct patients had a higher degree of stenosis or occlusion in either the middle cerebral or internal carotid artery (P=0.008) and exhibited a rosary-like pattern of infarction more frequently (P<0.001). In contrast, concomitant small cortical infarcts were observed more frequently in CBZ infarct patients (P<0.001). Clinical deterioration during the first 7 days of admission and poor outcome after 3 months after stroke was more prevalent in IBZ infarct patients than in CBZ infarct patients (P=0.002 and P=0.003, respectively).

CONCLUSIONS

IBZ infarcts are caused mainly by hemodynamic compromise, whereas embolic pathogenesis appears to contribute greatly to the genesis of CBZ infarcts. Patients with IBZ infarcts showed poor early and late clinical courses. Our findings suggest that different therapeutic approaches may be required to prevent early clinical deterioration in patients with different types of border-zone infarcts.

Acute intravenous low- and high-dose cocaine reduces quantitative global and regional cerebral blood flow in recently abstinent subjects with cocaine use disorder

Cocaine-induced hypoperfusion, a risk factor for ischemic stroke, has not been fully characterized during experimental drug-taking among individuals with cocaine use disorder. We sought to examine cocaine's dose-dependent, time-related effects on cerebral blood flow. In a double-blind, randomized human laboratory study with a counterbalanced order of drug administration, 31 male and female subjects with cocaine use disorder were divided into two groups receiving either (a) low-dose cocaine (0.325 mg/kg intravenously) or placebo (N=15) or (b) high-dose cocaine (0.650 mg/kg intravenously) or placebo (N=16). The different dose conditions were administered on test days separated by a rest period of >or=48 h. Cerebral blood flow was assessed quantitatively using H(2)O(15) positron emission tomography. Experimentally administered low- and high-dose cocaine conditions versus their corresponding placebo conditions were associated with global and regional hypoperfusion. The trend for high- versus low-dose cocaine to be associated with greater hypoperfusion achieved statistical significance only for the dopamine-rich sublobar and midbrain regions. Cocaine's hypoperfusion effects were maximal at 8 mins after infusion (i.e., at about the expected peak of intravenous cocaine levels) and had mostly dissipated by 32 mins after infusion. Although hypoperfusion occurred throughout the brain, the left hemispheric dopamine-rich sublobar region was the most severely affected. Cocaine-induced cerebral hypoperfusion is associated with the time course of its pharmacological effects, and dopamine-rich areas, particularly in the left hemisphere, may be most vulnerable. Increasingly larger doses of cocaine may be associated with greater risk for ischemic stroke.