Vascular cognitive impairment in patients with late-onset seizures after an ischemic stroke

BACKGROUND

Cognitive impairment and seizures are both common conditions in patients with cerebrovascular disease.

PURPOSE

The present study investigates whether the occurrence of late-onset seizures, following an ischemic stroke, contributes to vascular cognitive impairment.

PATIENTS AND METHODS

The mean Mini-Mental State Examination (MMSE) and the median modified Rankin (mR) scores were compared between 125 patients who developed late-onset seizures (66 with a single seizure and 59 with repeated seizures or epilepsy) following an ischemic stroke and 125 patients who did not during, at least, a 2-year follow-up.

RESULTS

There were no differences in age, gender, etiology and degree of neurological impairment on admission for their stroke between the groups with and without seizures. Although the mean MMSE score was similar between both groups the median mR score was significantly higher in the seizure patients. Comparing the patients with a single seizure to the non-seizure ones showed the same results. On the other hand, comparison of the patients with epilepsy to the non-seizure group revealed, in addition to the higher median mR score, a significantly lower mean MMSE score in the former group.

CONCLUSION

Repeated seizures following an ischemic stroke promote vascular cognitive impairment.

Cobalt-55 positron emission tomography in symptomatic atherosclerotic carotid artery disease: borderzone versus territorial infarcts

BACKGROUND

Borderzone as well as territorial infarcts can occur in severe atherosclerotic carotid artery disease. It remains controversial whether the borderzone distribution of infarcts is due to hypoperfusion or due to artery-to-artery embolism.

PURPOSE

The present study investigates whether cobalt-55 (55Co) positron emission tomography (PET) shows a different pattern of ischaemia according to the topography of the infarct in severe atherosclerotic carotid artery disease.

PATIENTS AND METHODS

Five patients with a cortical borderzone and seven with a territorial infarct, due to symptomatic carotid artery disease, were investigated with 55Co PET 3-6 months after stroke. Average 55Co counts in the infarct area, the adjacent cortical zone, the deep white matter and, contralateral cerebral cortex and white matter, were compared to the values in the cerebellum used as reference.

RESULTS

No differences in 55Co ratio were observed in the different regions of interest (ROIs) between patients with cortical borderzone and those with territorial infarcts. The 55Co uptake was similar or lower than the reference value for all ROIs in all individual patients.

CONCLUSION

In patients with borderzone as well as with territorial infarcts no evidence was found for subclinical ischaemic injury in or around the infarcts. These data do support the conclusion that cortical borderzone infarcts may not be due to ongoing chronic haemodynamic impairment, but by no means is this conclusive evidence.

Cobalt-55 positron emission tomography in vascular dementia: significance of white matter changes

BACKGROUND

Vascular dementia (VaD) is still used as a covering term to indicate the relationship between cerebrovascular disease and the progressive cognitive disorder. The contribution of white matter changes (WMCs), seen with computed tomography (CT) and magnetic resonance imaging (MRI) of the brain, to dementia had not been fully elucidated. Cobalt-55 (55Co) positron emission tomography (PET) allows us to distinguish between recent and old infarcts.

PURPOSE

The present study investigates whether 55Co PET can detect the lesions responsible for the progression of the cognitive disorder in VaD patients.

PATIENTS AND METHODS

20 consecutive patients with a previous history of repeated strokes occurring more than 6 months before and with multiple cortical infarcts, lacunes and WMCs on CT and 5 age-matched controls were investigated with 55Co PET. The stroke patients were divided in two groups: 8 with and 12 without VaD. Average 55Co counts in cerebral cortex, deep gray nuclei and white matter were compared to the value in the cerebellum used as reference.

RESULTS

In the control group, the 55Co uptake was identical in the cerebral cortex and in the cerebellum, but lower in the deep gray nuclei and the cerebral white matter. When comparing the stroke groups with the control, the 55Co uptake was similar for the cerebral cortex and deep gray nuclei, but significantly increased in the cerebral white matter. The 55Co uptake was also more increased in the stroke group with VaD compared to the non-demented group.

CONCLUSION

55Co PET shows that the WMCs are due to the ongoing damage of probably ischaemic origin which is more prominent in stroke patients with progressive cognitive decline.

Cerebral hemodynamics in CADASIL before and after acetazolamide challenge assessed with MRI bolus tracking

BACKGROUND

White matter lesions in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) are underlaid by severe ultrastructural changes of the arteriolar wall. Although chronic ischemia is presumed to cause the tissue lesions, the pattern of perfusion abnormalities and hemodynamic reserve in CADASIL, particularly within the white matter, remains unknown.

METHODS

We used the MRI bolus tracking method in 15 symptomatic patients with CADASIL (5 with dementia) and 10 age-matched control subjects before and 20 minutes after the intravenous injection of acetazolamide (ACZ, 17 mg/kg). Cerebral blood flow (CBF), blood volume (CBV), and mean transit time (MTT) were calculated both in the cortex and in the white matter according to the singular value decomposition technique. Perfusion parameters were obtained in regions of hyperintensities and within the normal-appearing white matter as observed on T2-weighted images. Analysis was performed with both absolute and relative (region/whole brain) values.

RESULTS

A significant reduction in absolute and relative CBF and CBV was found within areas of T2 hyperintensities in white matter in the absence of significant variations of MTT. This reduction was more severe in demented than in nondemented patients. No significant change in absolute CBF and CBV values was observed in the cortex of patients with CADASIL. A decrease in relative CBF and CBV values was detected in the occipital cortex. After ACZ administration, CBF and CBV increased significantly in both the cortex and white matter of affected subjects, but the increase in absolute CBF was lower within areas of increased signal on T2-weighted images in patients than in the white matter of control subjects.

CONCLUSIONS

In CADASIL, both basal perfusion and hemodynamic reserve are decreased in areas of T2 hyperintensities in the white matter. This hypoperfusion appears to be related to the clinical severity. The significant effect of ACZ on CBF and CBV suggests that cerebral perfusion might be increased using pharmacological vasodilation in CADASIL.

Reduced vasomotor reactivity in cerebral microangiopathy : a study with near-infrared spectroscopy and transcranial Doppler sonography

BACKGROUND AND PURPOSE

Reduction of cerebral blood flow and vasomotor reactivity (VMR) are thought to play an important role in the pathogenesis of cerebral microangiopathy. The aim of our study was to determine whether near-infrared spectroscopy (NIRS) can detect a reduced VMR in patients with microangiopathy, whether NIRS reactivities correlate with VMR assessed by transcranial Doppler sonography (TCD), and whether the differing extents of patients' microangiopathy demonstrated on MRI or CT can be distinguished by both noninvasive techniques.

METHODS

We compared the VMR of 46 patients with cerebral microangiopathy with 13 age-matched control subjects. Patients were classified with the Erkinjuntti scale. We monitored cerebral blood flow velocity (CBFV) in both middle cerebral arteries by TCD, changes in concentration of oxyhemoglobin (HbO(2)), deoxyhemoglobin (Hb) and blood volume (HbT) by NIRS, mean arterial blood pressure, and end-tidal CO(2) (EtCO(2)) during normocapnia and hypercapnia. VMRs were calculated as percent change of CBFV (NCR) and as absolute change in concentration of HbO(2), Hb, and HbT per 1% increase in EtCO(2) (CR-HbO(2), CR-Hb, CR-HbT).

RESULTS

NCR and NIRS reactivities were significantly reduced in patients with cerebral microangiopathy. CR-HbO(2) and CR-Hb showed a close correlation with NCR, and NCR and NIRS reactivities were related to the severity of cerebral microangiopathy according to the Erkinjuntti scale. Validity of NCR and NIRS reactivities were similar.

CONCLUSIONS

VMR is reduced in patients with cerebral microangiopathy and can be noninvasively assessed in basal arteries (with TCD) and brain parenchyma (with NIRS). Reduction of CO(2)-induced VMR, as measured by NIRS and TCD, may indicate the severity of microangiopathy.

Positron emission tomography in vascular dementia

BACKGROUND

Vascular dementia (VaD) is an ill-defined entity. It is not known how acute brain failure related to stroke becomes chronic leading to dementia.

PURPOSE

The present study investigates whether positron emission tomography (PET) can detect different metabolic patterns in VaD.

PATIENTS AND METHODS

Four groups of stroke patients were selected. The PET findings of 14 stroke patients with multiple large infarcts and dementia (MID) and 14 without dementia (MS) were compared. Sixteen stroke patients with lacunes, leukoaraiosis and dementia (LD) were assessed against nine without dementia (LS). The PET examination utilised the 15-O-steady-state technique in order to determine regional cerebral blood flow (rCBF), regional oxygen extraction rate (rOER) and regional cerebral metabolic rate for oxygen (rCMRO2) in different pre-established cortical, subcortical and cerebellar regions.

RESULTS

Decreased coupled mean rCBF and rCMRO2 with comparable rOER values were observed in all cerebral regions except in the cerebellum of the MID compared to the MS group. In the LD group mean rCBF and rCMRO2 were decreased with increased rOER in all cerebral regions except in the cerebellum compared to the LS group.

CONCLUSIONS

The PET findings in demented patients with multiple large infarcts are in agreement with the concept of multi-infarct dementia. In demented patients with lacunes and leukoaraiosis, the PET pattern suggests a state of misery perfusion not only in the deep structures but also in the whole cerebral cortex. The present PET study argues that there are at least two possible mechanisms that can explain the occurrence of VaD in stroke patients.

Leuko-araiosis and stroke: a case-control study

OBJECTIVE

Association of leuko-araiosis (LA) with certain risk factors has been reported in Western patients. This is a case-control study to determine the risk factors and the type of stroke associated with LA in Saudi patients.

DESIGN AND SETTING

398 consecutive Saudi patients with the diagnosis of stroke admitted over a 6-year period were evaluated for presence or absence of LA on cranial computed tomography. LA and non-LA groups were compared with regards to the presence of certain risk factors such as type of stroke, age, brain atrophy, systemic hypertension and history of cardiac disease or diabetes mellitus. The odds ratio and its 95% confidence interval (CI) were used to estimate the strength of association between the different parameters.

RESULTS

The mean age in the LA group was 67.8 +/- 8.5 years as compared to 61.2 +/- 13.2 years in the non-LA group. No patient younger than 40 years had LA on CT. Incidence of LA increased with age. Forty-seven percent of the LA group were over 70 years of age compared to 31% of the non-LA group (OR = 2, CI 1.26-3.15). Generalised atrophy was detected in 40% of patients with LA compared to 20% of non-LA group (OR 2.7, CI 1.65-4.39). Sixty-nine percent of patients in the LA group had lacunar infarct compare to 39% in the non-LA group (OR 3.4, CI 2.15-5.59). The difference was not significant between the two groups in relation to the frequency of cerebral hemorrhage or larger infarcts. Systemic hypertension was also significantly associated with the presence of LA (OR 2.15, CI 1.34-3.43).

CONCLUSION

LA is associated mainly with lacunar infarcts, cerebral atrophy, systemic hypertension and advanced age in Saudi patients.

Risk factors and leukoaraiosis in stroke patients

OBJECTIVES

Although leukoaraosis (LA) is a common CT findings, its pathogenesis remains debated: if small-artery pathology may explain in some cases white matter changes, many other factors, such as hemodynamic perturbations, might also lead to LA. To test these hypothesis, we determined the types of cerebrovascular risk factors associated with leukoaraosis in consecutive patients with acute cerebrovascular event.

PATIENTS AND METHODS

Using CT-scans, we prospectively studied in 610 patients consecutively admitted for an acute cerebral event, the relation between LA and the following cerebrovascular risk factors: age, sex, arterial hypertension, diabetes mellitus, hyperlipemia, alcohol consumption, birth contraceptive pills, previous transient ischemic attack or stroke, migraine, atrial fibrillation, valvulopathy, coronaropathy, left ventricular hypertrophy, stenosis of the internal carotid artery, by means of a multiple linear regression. Relation with cerebral atrophy was also evaluated.

RESULTS

We found LA scores to depend on increasing age (p = 0.0001), female sex (p = 0.0146), history of stroke or TIA (p = 0.0051), history or current atrial fibrillation (p = 0.0083), increasing cerebral atrophy score (p = 0.0001), absence of hyperlipemia (p = 0.0003) and absence of alcohol consumption higher than 300 g/week (p = 0.0398).

CONCLUSION

Our findings do not support the hypothesis that, in stroke patients, LA share similar risk factors than small-vessel disease; other cerebrovascular risk factors may also contribute to LA, perhaps because of decreased cerebral blood flow.

Positron emission tomographic study of late-onset cryptogenic symptomatic seizures

Ten patients with epilepsy of unknown origin, starting after the age of 50 years, and without clear evidence of cognitive decline were studied with positron emission tomography, using the steady state technique with 15O. Cerebral blood flow and oxygen metabolism were significantly decreased in all cortical areas. No focal areas of hypometabolism were detected. Treatment with phenytoin did not influence the results. It is suggested that late-onset seizures could be the premonitory signs of a progressive encephalopathy of unknown origin.

Functional circulation images by angio-CT in the assessment of small deep cerebral infarctions

We analyzed circulation time (rABCT) and vascular volume density images obtained by angio-computerized tomography (angio-CT) in 63 patients with small deep cerebral infarctions. Abnormalities in the rABCT image were found in 88% of the patients and in the vascular volume image in 48%. Two groups with different clinical pictures were picked out by rABCT changes: one with major-vessel involvement, the other with small-vessel involvement. The perfusional changes found were mainly due to altered vascular canalization rather than to altered vasomotility. The hemodynamic theory could explain the spatial relations between perfusion changes and CT hypodense areas without needing assumptions linking blood flow and metabolism.

Pontine ischemic rarefaction

To investigate apparently asymptomatic, bilateral symmetrical predominantly pontine hyperintensities (PHI) on magnetic resonance imaging (MRI) scans in elderly patients, we examined the pons histopathologically in two brains of elderly hypertensives with PHI, and in three without PHI, on postmortem MRI scans. We also reviewed 85 serial in vivo MRI scans of patients over 60 and compared scan findings, vascular risk factors, and clinical symptoms between patients with PHI and a control group. A subcortical arteriosclerotic encephalopathy (SAE)-like pathology was present in the pons in only the two autopsy brains with PHI and corresponded with the location of PHI on the postmortem MRI scans and with the most frequent sites of PHI on in vivo scans. SAE also involved the hemispheric white matter in one of the autopsy brains. Five of 16 (31%) patients with, and 4 of 69 (6%) without, PHI on in vivo MRI scans had marked periventricular hyperintensity (PVHI) compatible with SAE (p = 0.01). We conclude that an SAE-like pathology may be seen in the pons in elderly hypertensives and this pathology is probably the cause of PHI seen on MRI scans of patients over 60 years of age.

[Morphological imaging in the diagnosis of dementia. II. Vascular dementia]

Magnetic resonance imaging (MRI) and CT-scan are crucial for the diagnosis of cerebrovascular diseases. Multi-infarct dementias may be divided into (i) dementias due to multiple cortical infarcts and (ii) dementias due to multiple lacunar infarcts in the basal ganglia, thalamus and hemispheric white matter, usually associated with leukoaraiosis. A single infarct located in the thalamus or in the left angular gyrus may also induce dementia. Abnormalities of the cerebral white matter, so-called leukoaraiosis, are usually the consequence of a cerebrovascular disease and may be called Binswanger's disease in severe cases. However, leukoaraiosis is not specific of vascular dementia and may also be found in Alzheimer's disease and even in normal aging.

[Contribution of morphological imaging in the diagnosis of dementia. I--Alzheimer disease]

In patients with Alzheimer's disease, morphological neuroimaging techniques usually reveal signs of global cerebral atrophy which gradually worsen over time and depends on age and severity of the cognitive decline. Because of the lack of artifacts and of a more appropriate angle, magnetic resonance imaging scans may visualize a prominent atrophy of the medial temporal lobes, including hippocampal structures. Hippocampal atrophy is relatively specific of Alzheimer's disease before 65 and is related to the severity of memory disorders. White matter changes in patients without cerebrovascular risk factors are not more severe in patients with presenile Alzheimer's disease than in age-matched controls. They are, however, more severe in patients with senile onset than in age-matched controls. These findings suggest that white matter changes in patients with senile onset are consistent with a diagnosis of Alzheimer's disease.

Decreased cerebrovascular dilatory capacity in subjects with asymptomatic periventricular hyperintensities

BACKGROUND AND PURPOSE

The clinical significance of the periventricular hyperintensity incidentally found on magnetic resonance images of the brain is questionable. We evaluated resting cerebral blood flow and cerebrovascular dilatory capacity of subjects with asymptomatic periventricular hyperintensities to study their cerebral hemodynamics.

METHODS

Magnetic resonance imaging of the brain was performed in 28 asymptomatic subjects with cerebrovascular risk factors to determine the severity of periventricular hyperintensity. Mean gray matter flow was computed by a 133Xe-clearance technique in subjects at rest and after the administration of 1 g acetazolamide. Flow values were correlated with the scores for periventricular hyperintensity.

RESULTS

Resting gray matter flow was not significantly correlated with the severity of periventricular hyperintensity for the whole brain (rs = -.364), whereas flow after acetazolamide loading (rs = -.783, P < .001) and the absolute value of increased flow (rs = -.567, P < .01) were significantly and negatively correlated with the severity of periventricular hyperintensity.

CONCLUSIONS

A decrease in vasodilatory capacity and compensatory vasodilation occur in the cerebral cortex of subjects with asymptomatic periventricular lesions and maintain cerebral blood flow.

Lacunar infarcts and white matter attenuation. Ophthalmologic and microcirculatory aspects of the pathophysiology

BACKGROUND AND PURPOSE

By means of neurological and ophthalmologic examinations we considered whether there is a microcirculatory disorder not related to hypertension and diabetes in patients with lacunar infarcts and whether there are microcirculatory differences in patients with lacunar infarcts compared with those with white matter attenuation.

METHODS

Eighty neurological patients with a lacunar infarct underwent computed tomography and, based on the results, were prospectively assigned to subgroups as follows: (1) patients without changes; (2) patients with white matter attenuation but without lacunar infarcts; (3) patients with lacunar infarcts alone; and (4) patients with both lacunar infarcts and white matter attenuation. Clinical and ophthalmologic parameters were monitored. The retinal microcirculation was studied by videofluorescence angiography. These neurological patients were compared with control ophthalmologic patients matched for age, sex, hypertensive and diabetic ocular fundus changes, and smoking habits.

RESULTS

On average, the 80 patients with lacunar infarcts had a significantly (P = .0001) slower arteriovenous passage time (2.6 +/- 0.7 seconds) than the ophthalmologic control subjects (1.6 +/- 0.6 seconds). Arteriovenous dye passage time through the retinal microcirculation was nearly normal (2.2 +/- 0.8 seconds) in patients with white matter attenuation alone, but was significantly prolonged in patients with lacunar infarcts (2.9 +/- 0.8 seconds, P = .00085) or both white matter attenuation and lacunar infarcts (2.8 +/- 0.4 seconds, P = .008).

CONCLUSIONS

Patients with lacunar infarcts are characterized by an additional disorder of retinal microcirculation independent of arterial hypertension and diabetes. Our data suggested that white matter attenuation and lacunar infarcts may be phenomena with only weak interdependence.

Magnetic resonance imaging findings associated with cardiac arrest

BACKGROUND AND PURPOSE

The frequency and prognostic significance of neuroradiological findings after cardiac arrest are unknown. Using healthy volunteers as control subjects, we studied the magnetic resonance imaging (MRI) findings associated with cardiac arrest, adjusted for confounding factors.

METHODS

The presence of cerebral infarcts, leukoaraiosis, atrophy, and edema on ultra-low-field MRI was assessed in 88 community volunteers and 52 cardiac arrest survivors enrolled in a placebo-controlled, randomized, double-blind trial of nimodipine in out-of-hospital ventricular fibrillation.

RESULTS

Cardiac arrest was an independent risk factor for the presence of infarcts in a logistic regression model adjusted for age, sex, and history of myocardial infarction, stroke, coronary heart disease, cardiac failure, and hypertension (odds ratio, 3.6; 95% confidence interval, 1.3 to 9.9; P = .01). Leukoaraiosis was associated with increasing age but not with cardiac arrest. Adjusted for age, the delay of advanced life support had an inverse correlation with the degree of atrophy in placebo-treated patients (r = -.62, P < .0001) but not in patients treated with nimodipine (r = -.10, P = .43). Lack of age-related atrophy, possibly implicating the presence of brain edema, predicted poor outcome after cardiac arrest (odds ratio, 4.6; 95% confidence interval, 1.4 to 15.8; P = .01).

CONCLUSIONS

Cardiac arrest was associated with deep cerebral infarcts but not with leukoaraiosis. MRI findings did not predict the functional outcome at 1 year. Nimodipine treatment had no significant effect on the MRI findings, but delayed resuscitation was associated with probable brain edema only in placebo-treated patients.