Johanna Helenius

Cerebral Hemodynamics in Asymptomatic and Symptomatic Patients With High-Grade Carotid Stenosis Undergoing Carotid Endarterectomy

Background and Purpose— Asymptomatic patients with carotid stenosis benefit less from carotid endarterectomy (CEA) than symptomatic patients because the risk of embolic events is lower, but it is not known whether the hemodynamic effect of CEA is different between the groups. We evaluated hemodynamics of symptomatic and asymptomatic patient groups before and after CEA. Methods— Forty-six independent patients with a unilateral high-grade carotid stenosis, 23 asymptomatic and 23 symptomatic, underwent dynamic susceptibility contrast MRI (DSC-MRI) and transcranial Doppler ultrasound (TCD) evaluation before CEA and 3 and 100 days afterward. Quantitative perfusion parameters were calculated separately in selected regions of white and gray matter and watershed regions in each hemisphere, and mean transit time (MTT) maps were assessed visually by 2 independent observers. Vasomotor reactivity was determined with breath-holding index and flow impedance with pulsatility index ipsilaterally. Results— In contrast to the asymptomatic carotid stenosis group, symptomatic carotid stenosis patients had preoperatively increased MTT and lower cerebral blood flow values in the ipsilateral hemisphere, more in white matter and watershed regions than in gray matter. Visually detected perfusion deficits were associated with symptomatic status. The interhemispheric asymmetries were abolished by CEA. The improving trend over time was greater in the symptomatic carotid stenosis group and was best seen in MTT. On TCD, pulsatility index was lower in symptomatic carotid stenosis patients preoperatively, with no postoperative difference, whereas the breath-holding index improved only in the symptomatic carotid stenosis group after CEA. Conclusions— Patients with asymptomatic and symptomatic carotid stenosis differ significantly by means of DSC-MRI and TCD before and in response to CEA.

Cerebral Hemodynamics in a Healthy Population Measured by Dynamic Susceptibility Contrast Mr Imaging

Purpose: To establish reference data and to study age-dependency for cerebral perfusion in various regions of the brain in a healthy population. Material and Methods: Eighty healthy subjects of both genders from 22 to 85 years of age were studied with spin echo echo-planar dynamic susceptibility contrast MR imaging (DSC MRI) at 1.5 T. Cerebral blood volume (CBV), cerebral blood flow (CBF), and contrast agent mean transit time (MTT) were calculated bilaterally for 20 distinct neuroanatomic structures. Results: In gray matter, the following values were found (mean ± SD): CBV (4.6 ± 1.0 ml/100 g), CBF (94.2 ± 23.0 ml/100 g/min), and MTT (3.0 ± 0.6 s), and in white matter: CBV (1.3 ± 0.4 ml/100 g), CBF (19.6 ± 5.8 ml/100 g/min), and MTT (4.3 ± 0.7 s). The perfusion parameters did not change with age, except for a tendency to an increase in gray matter MTT and CBV. Males exhibited higher MTT and CBV than females. No hemispheric difference was found in either gender. Conclusion: Cerebral hemodynamics can be assessed with DSC MRI. Age itself seems to have only a marginal effect on cerebral perfusion in healthy population.

Concurrent acute brain infarcts in patients with monocular visual loss

Embolism from a proximal source to the retinal circulation could be a sign of embolism from the same source to the hemispheric circulation. We sought to determine the frequency of acute brain infarcts on diffusion‐weighted imaging (DWI) in patients with monocular visual loss of presumed ischemic origin (MVL).

Extensive Leukoaraiosis Is Associated With High Early Risk of Recurrence After Ischemic Stroke

Background and Purpose— The integrity of white matter tracts connecting different parts of the brain is important for rapid compensation for the lost function from ischemic stroke. Impaired white matter reserve capacity secondary to leukoaraiosis may facilitate detection of new symptomatic ischemic events that would otherwise remain inconspicuous after an initial ischemic stroke. We sought to identify whether the extent of leukoaraiosis was a predictor of risk of early stroke recurrence. Methods— We used Cox regression analysis in consecutive patients with ischemic stroke to determine the relationship between leukoaraiosis burden and symptomatic stroke recurrence within 90 days. We graded total leukoaraiosis, periventricular leukoaraiosis, and subcortical leukoaraiosis using the Fazekas scale as mild (<2) and extensive (≥2) on fluid-attenuated inversion recovery images obtained within 72 hours of stroke onset in the hemisphere contralateral to acute stroke. Results —There were 106 recurrent events in 2378 patients. The cumulative incidence of recurrence was 5.9% at 90 days. Kaplan–Meier estimate of recurrence-free survival rate was lower in patients with extensive leukoaraiosis (P=0.04) and extensive periventricular leukoaraiosis (P=0.02) but not in extensive subcortical leukoaraiosis (P=0.09). Multivariable Cox regression analysis revealed a hazard ratio of 1.50 (95% confidence interval, 1.00–2.25) for extensive leukoaraiosis, 1.67 (95% confidence interval, 1.11–2.51) for extensive periventricular leukoaraiosis, and 1.42 (95% confidence interval, 0.94–2.12) for extensive subcortical leukoaraiosis. Conclusions— The extent of leukoaraiosis independently predicts 90-day recurrent stroke risk after ischemic stroke. This suggests that leukoaraiosis may be used for risk stratification in ischemic stroke.

Adult cervicocerebral artery dissection: a single-center study of 301 Finnish patients.

Background and purpose:  There are only few small studies assessing potential risk factors, comorbidity, and prognostic factors in adult spontaneous cervicocerebral artery dissection (CAD).

Serial measurements of plasma homocysteine levels in early and late phases of ischemic stroke

High plasma levels of homocysteine (Hcy) may predispose to ischemic stroke (IS), but results of previous studies have been conflicting. We decided to determine in IS patients whether their Hcy levels are elevated, whether levels vary at different time points following stroke, whether levels are associated with stroke severity, outcome, recurrence, etiology, infarct volume, or risk factors, and whether levels are correlated with hemostatic factors or C‐reactive protein values. We measured plasma Hcy levels in 102 consecutive IS patients on admission and at 1 week, 1 month, and 3 months after stroke and once in 102 control subjects. Hemostatic factors were measured in 55 patients. Compared with controls, plasma Hcy levels in patients were significantly lower on admission but not at later time points, with levels increasing by week and remaining at this level for 3 months. Hcy levels showed a positive correlation with age and a negative correlation with Mini‐Mental State Examination (MMSE) scores. Plasma Hcy levels inversely correlated with plasminogen activator inhibitor type‐1. Decreased Hcy levels on admission may reflect the strength of the acute‐phase response rather than a pathogenetic event. The negative correlation between Hcy levels and MMSE scores is more probably age‐related than stroke‐related.

Marchiafava-Bignami disease: two cases with favourable outcome.

Marchiafava–Bignami disease (MBD) is a rare disorder of an unknown aetiology but strongly associated with alcoholism. MBD primarily affects the corpus callosum leading to confusion, dysarthria, seizures and frequently to death. Over 250 cases from all races and from almost all nationalities have been reported, most cases being alcoholics. We report two cases with a favourable outcome. Magnetic resonance imaging (MRI) demonstrated a typical lesion of the corpus callosum, in both patients. The patients, a 44‐year‐old male and a 40‐year‐old female, presented with depressed consciousness and a variety of other symptoms, but finally made a reasonably good recovery leading to home discharge. To the best of our knowledge, only one additional case of MBD from Scandinavia has been published. As alcoholism is a major public health problem in Scandinavia, we assume that MBD is underdiagnosed and/or under‐reported. Non‐specific general symptoms and encephalopathy in an alcoholic may harbour undiagnosed MBD. We suggest that the incidence of MBD may be higher and its prognosis may be milder than generally believed.

Brain diffusion changes in carotid occlusive disease treated with endarterectomy

Background: Patients with unilateral high-grade carotid stenosis or occlusion have been reported to have more leukoaraiosis and ischemic lesions in ipsilateral than in contralateral cerebral hemisphere. The lesions alter apparent diffusion coefficient (ADC) values in diffusion-weighted MRI (DWI). The overall effects of carotid endarterectomy on ADC values have not yet been explored. Objectives: To find out whether 1) average ADC (ADCav) values differed between hemispheres, 2) diffusion changes induced by carotid endarterectomy could be detected in brain tissue with serial DWI, and 3) patients with asymptomatic carotid stenosis differed from patients with a symptomatic stenosis. Methods: Forty-five patients (22 with asymptomatic carotid stenosis and 23 with symptomatic carotid stenosis) with unilateral high-grade carotid stenosis underwent DWI before carotid endarterectomy and 3 and 100 days afterward, and 45 age- and sex-matched healthy control subjects were imaged once. We evaluated ADCav values in normal-appearing gray and white matter, watershed regions (WsR), and thalamus. Results: ADCav values of ipsilateral white matter and WsR were higher than those of contralateral white matter and WsR, both being higher than in white matter and WsR of control subjects. After carotid endarterectomy, these differences were diminished, but the levels remained higher than in controls. ADCav values of gray matter and thalamus remained unaffected. Asymptomatic carotid stenosis and symptomatic carotid stenosis patient groups did not differ from each other. Conclusions: Carotid stenosis has an effect on diffusion in the white matter of the ipsilateral hemisphere, and it is partly reversible by carotid endarterectomy. The finding may be associated with leukoaraiotic development (“preleukoaraiosis”).

Abnormal Intravoxel Cerebral Blood Flow Heterogeneity in Human Ischemic Stroke Determined by Dynamic Susceptibility Contrast Magnetic Resonance Imaging

Background and Purpose— The determination of cerebral blood flow heterogeneity (FH) by dynamic susceptibility contrast (DSC) magnetic resonance imaging has recently been proposed as a tool to predict final infarct size in acute stroke. In this study, we describe the evolution of FH during the first week as well as its correlation to the patients’ clinical status. Methods— Ten patients with ischemic stroke were studied with DSC MRI and diffusion-weighted imaging in hyperacute (<6 hours) phase, at 24 hours, and 1 week after symptom onset. In addition to intravoxel FH, cerebral blood volume (CBV), cerebral blood flow (CBF), and contrast agent mean transit time (MTT) were determined from DSC MRI. All patients were evaluated neurologically with National Institute of Health Stroke Scale concurrently with the imaging sessions. Results— All patients showed infarct growth, judged by diffusion-weighted imaging, during the week with simultaneous decrease in the sizes of FH, CBV, CBF, and MTT abnormalities. The FH abnormality was shown to be larger than CBV and CBF abnormalities at the hyperacute phase and 24 hours, but smaller than MTT abnormality in all 3 imaging sessions. The sizes of hyperacute FH, CBV, CBF, and MTT abnormalities correlated well with infarct size at 24 hours and at 1 week. Additionally, FH was the only perfusion parameter that correlated with the clinical score. Conclusions— FH predicts infarct size equally well with the other perfusion parameters but is superior in correlation with the clinical score. FH can easily be incorporated to hyperacute stroke imaging without additional efforts.

The Effect of Severe Carotid Occlusive Disease and Its Surgical Treatment on Cognitive Functions of the Brain.

Surgery of a high-grade carotid stenosis is evidence-based stroke prevention. Also cognitive effects are reported after carotid endarterectomy (CEA): both deterioration and improvement, the former attributed to perioperative complications and the latter often to learning effect. By imaging, brain perfusion and diffusion changes were shown in subjects with a high-grade stenosis undergoing CEA. We wanted to find out if the cognition of patients undergoing CEA display postoperative worsening or true improvement in association with findings in serial MR imaging. The patients had a poorer overall cognition than healthy matched controls. The cerebral hemisphere ipsilateral to the stenosis had higher diffusion and more sluggish perfusion leading to perfusion deficits. These asymmetries were abolished by CEA. Postoperatively, the patients showed a trend for cognitive worsening, most often attentional, but over months, the group performance improved similarly to the controls. Still, lower baseline perfusion was associated with a greater cognitive improvement, most clearly in executive functions. Consequently, despite the risk for transient decline, true cognitive benefit by CEA seems possible.