In vivo quantification of brain volumes in subcortical vascular dementia and Alzheimer's disease. An MRI-based study

Quantitative magnetic resonance imaging (MRI) was used to assess global and regional cerebral volumes in patients with a clinical diagnosis of subcortical vascular dementia (VD) and Alzheimer's disease (AD). Whole brain volume, cerebrospinal fluid volume, volumes of the temporal, frontal and parietal lobes, the cerebellum and the amygdala-hippocampus complex were determined using a personal computer-based software. Seventeen patients with VD, 22 patients with AD and 13 healthy controls were included. Analysis of covariance using age as covariate demonstrated significant mean differences between controls and dementia groups with respect to all morphological parameters. However, apart from the volume of the cerebellum no significant volumetric differences were found between VD and AD. These results indicate that MRI-based volumetry allows differentiation between AD or VD from normal controls and that measurement of cerebellar volume may be of use to separate vascular and degenerative dementia. However, since the distribution of cerebral atrophy in both dementia groups is very similar, it is suggested that the atrophic changes are not specific to the underlying cause but rather reflect the selective vulnerability of neuronal structures.

Randomised double-blind placebo-controlled trial of thrombolytic therapy with intravenous alteplase in acute ischaemic stroke (ECASS II). Second European-Australasian Acute Stroke Study Investigators

BACKGROUND

Thrombolysis for acute ischaemic stroke has been investigated in several clinical trials, with variable results. We have assessed the safety and efficacy of intravenous thrombolysis with alteplase (0.9 mg/kg bodyweight) within 6 h of stroke onset.

METHODS

This non-angiographic, randomised, double-blind, trial enrolled 800 patients in Europe, Australia, and New Zealand. Computed tomography was used to exclude patients with signs of major infarction. Alteplase (n=409) and placebo (n=391) were randomly assigned with stratification for time since symptom onset (0-3 h or 3-6 h). The primary endpoint was the modified Rankin scale (mRS) at 90 days, dichotomised for favourable (score 0-1) and unfavourable (score 2-6) outcome. Analyses were by intention to treat.

FINDINGS

165 (40.3%) alteplase-group patients and 143 (36.6%) placebo-group patients had favourable mRS outcomes (absolute difference 3.7%, p=0.277). In a posthoc analysis of mRS scores dichotomised for death or dependency, 222 (54.3%) alteplase-group and 180 (46.0%) placebo-group patients had favourable outcomes (score 0-2; absolute difference 8.3%, p=0.024). Treatment differences were similar whether patients were treated within 3 h or 3-6 h. 85 (10.6%) patients died, with no difference between treatment groups at day 90+/-14 days (43 alteplase, 42 placebo). Symptomatic intracranial haemorrhage occurred in 36 (8.8%) alteplase-group patients and 13 (3.4%) placebo-group patients.

INTERPRETATION

The results do not confirm a statistical benefit for alteplase. However, we believe the trend towards efficacy should be interpreted in the light of evidence from previous trials. Despite the increased risk of intracranial haemorrhage, thrombolysis with alteplase at a dose of 0.9 mg/kg in selected patients may lead to a clinically relevant improvement in outcome.

Effect of training in reading CT scans on patient selection for ECASS II

Anticipating that patients with large ischemic lesions exceeding one-third of the middle cerebral artery (MCA) territory and detected on CT scans within 6 hours of stroke onset will not benefit from thrombolysis, we trained each participant of the second European Cooperative Acute Stroke Study (ECASS II) in the recognition of early ischemic lesions. Participants (n=532; neurologists, radiologists, neuroradiologists) were tested before and after each 4-hour CT reading training course. We asked the participants to estimate the extent of acute ischemic lesions on 10 CT scans, which we presented for 90 seconds without clinical information. Two sets of 10 CT scans each (A and B) were alternatively presented to each group, so that 254 participants evaluated set A before the training and 278 participants evaluated set B. We compared the numbers of correct estimates, underestimations, and overestimations before and after the course for each participant. The person who taught all courses (RvK) provided the reference estimates. We found that training significantly increased the number of correct estimates (p < 0.0001). Subsequently, we studied the incidences of large infarctions and parenchymal hemorrhages in the ECASS II population. In comparison with ECASS I investigators, the local investigators of ECASS II reduced the number of falsely included patients to an extent similar to that of the training courses. More remarkably, among the ECASS II patients, the proportion of patients with large infarctions or parenchymal hemorrhages was reduced to 50%. Careful CT reading may have contributed to this result.

[Systemic thrombolysis with plasminogen activator in chronic stroke patients]

Following the study protocol, we stratified the 615 patients of ECASS I according age (< or =/-70 years) and analysed the response to intravenous rt-PA in both subgroups. The older patients (248) suffered from the same stroke severity as the younger patients (367) experienced, however, a more severy clinical course (placebo group after 3 months after stroke: Barthel Index 50 vs. 85, mortality 24% vs. 11%). Treatment with rt-PA increased the proportion of undisabled patients at 3 months after stroke onset significantly only in the younger patients. The risk for brain parenchymal hemorrhage was increased by the factor of 4.7 and 4.6 in both age groups. It is obviously harder to achieve an undisabled state by systemic thrombolysis in the elderly. Facing the risk of brain hemorrhage associated with rt-PA, the risk-benefit-ratio may be less favourable in patients over 70 years.

The ECASS 3-hour cohort. Secondary analysis of ECASS data by time stratification. ECASS Study Group. European Cooperative Acute Stroke Study

OBJECTIVES

(1) To determine whether and how outcome measurements in the ECASS trial are influenced by a shorter time window (0-3 vs. 3-6 h) between onset of symptoms and start of thrombolytic therapy using recombinant tissue plasminogen activator (rt-PA) in acute ischemic stroke. (2) To discuss the results of the ECASS 0- to 3-hour cohort with the results of the National Institute of Neurological Disorders and Stroke Study (NINDSS).

DESIGN AND ANALYSIS

Analysis of the 0- to 3-hour and the 3- to 6-hour cohort in accordance with the ECASS protocol. Comparative analysis of the ECASS and NINDSS results following the NINDSS protocol using dichotomized endpoints.

MAIN OUTCOME MEASURES

Primary endpoints: modified Rankin Scale, Barthel Index; secondary endpoints: combined Barthel/Rankin, long-term Scandinavian Stroke Scale, National Institutes of Health Stroke Scale, mortality at 30 and 90 days, occurrence of intracranial hemorrhage. NINDS trial endpoint: favorable outcome as defined in the NINDS trial.

RESULTS

In ECASS, 87 patients were randomized within 3 h of stroke onset. Differences in favor of rt-PA treatment can be found for all primary and secondary outcome measures in the ECASS 0- to 3-hour cohort, except for mortality at day 30, which is somewhat higher in the rt-pA-treated group. However, due to the small sample size, the differences do not reach statistical significance. Early infarct signs (as defined by the ECASS protocol) are found as early as 2 h after stroke onset. Parenchymal hemorrhages are found significantly more often among rt-PA-treated patients. The results in the ECASS 0- to 3-hour cohort fit well with the results in NINDSS.

CONCLUSION

Data from the 3-hour ECASS cohort support the efficacy of early thrombolytic therapy in acute hemispheric stroke patients. Comparing bleeding complications between the ECASS and NINDSS is difficult because of differences in the definition and occurrence of hemorrhagic events.

[Acute ischemic cerebral infarct: prospective serial observations by magnetic resonance imaging]

AIM

Serial observations of acute ischaemic cerebral infarcts by MRI in order to define signal patterns, contrast uptake, oedema and secondary haemorrhage over a period of three months.

METHODS

Prospective serial examinations of 34 patients with acute cerebral ischaemia who were examined during the first 48 hours, on days 3 or 4, 7, 14, 21, 28 and after three months by MRI (spin echo TR/TE 2200/100/20, 500/20, +/- Gd).

RESULTS

T2 weighted spin echo sequences showed the highest sensitivity (88%) during the first 8 hours of cerebral ischaemia when compared with other spin echo sequences. Parenchymal contrast enhancement showed a distinct peak during the second and third weeks. The use of contrast did not improve diagnosis of an infarct during any stage. 87% of lesions showed haemorrhage at some stage. Vascular enhancement was observed in 25% of infarcts during the first 24 hours and was still present after three months in 20%. Parenchymal and vascular enhancement, and haemorrhage correlate with the size of the infarct.

CONCLUSION

Focal cerebral ischaemia produces an abnormality of the blood-brain barrier, oedema and finally necrosis, depending on the severity and duration of the lesion. Haemorrhage in 87% was considerably more common than has been described previously. Vascular enhancement is not an early sign of an infarct, contrary to what has been described in the literature.

Does NO regulate the cerebral blood flow response in hypoxia?

OBJECTIVES

To study whether nitric oxide (NO) affects the CBF response to hypoxic and carbon monoxide (CO) hypoxia.

MATERIAL AND METHODS

We incrementally reduced arterial oxygen content in rats, by decreasing the concentration of inspired oxygen (20 rats) or by repeated CO inhalation (20 rats), and measured local CBF using the hydrogen clearance method. Ten animals of each group received 80 mg/kg NO synthase (NOS) inhibitor N-monomethyl-L-arginine intravenously prior to hypoxia, while 10 rats served as controls.

RESULTS

Inhibition of NOS decreased mean CBF by 30% and increased cerebrovascular resistance by 70%. Under hypoxic hypoxia, mean oxygen reactivity of CBF (relative change of CBF to a change of arterial oxygen content) was 7.8%/vol% in control animals and 3.3%/vol% after NOS inhibition (P < 0.02). Under CO hypoxia, mean oxygen reactivity was 7.3%/vol% in control animals and 5.1%/vol% after NOS inhibition (P < 0.05). Inhibition of NOS diminished significantly the cerebral vasodilatory response during hypoxic hypoxia (P < 0.05) but only to a lesser extent during CO hypoxia.

CONCLUSION

These observations suggest that NO is involved in cerebral oxygen vasoreactivity, particularly in severe hypoxia.

Are iodinated contrast agents detrimental in acute cerebral ischemia? An experimental study in rats

PURPOSE

To study the effects of iothalamate sodium and two dosages of iopromide in acute cerebral ischemia on infarction volume, neurologic performance, and mortality in a rat model of middle cerebral artery occlusion.

MATERIALS AND METHODS

Sixty-four rats underwent endovascular occlusion of the middle cerebral artery. Four hours later, 16 animals received iothalamate sodium (588 mg iodine per kilogram); 16, iopromide as a single bolus (518 mg iodine per kilogram); and 16, iopromide as a double bolus (1,036 mg iodine per kilogram). Sixteen animals received equivolumetric saline (control group). Neurologic score and body weight were recorded every 8 hours. Twenty-four hours after occlusion, all animals were killed; brains were stained to assess the infarction size.

RESULTS

Single and double doses of iopromide did not affect infarction volume or neurologic performance. Iothalamate caused an increase in infarction volume and worsening of the neurologic score (p < .05). Mortality rate was 25% in the iothalamate group, 12% in the control group, and 6% in the iopromide groups.

CONCLUSION

Bolus injection of the nonionic iopromide does not statistically significantly affect infarction volume or cerebral ischemia symptoms. Nonionic rather than ionic contrast agents should be preferred during acute cerebral ischemia.

Acute stroke: usefulness of early CT findings before thrombolytic therapy

PURPOSE

To determine whether the extent of subtle parenchymal hypoattenuation detected on computed tomographic (CT) scans obtained within 6 hours of ischemic stroke is a factor in predicting patients' response to thrombolytic treatment.

MATERIALS AND METHODS

The baseline CT scans of 620 patients, who received either recombinant tissue plasminogen activator (rt-PA) or a placebo, in a double-blind, randomized multicenter trial were prospectively evaluated and assigned to one of three categories according to the extent of parenchymal hypoattenuation: none, 33% or less (small), or more than 33% (large) of the middle cerebral artery territory. The association between the extent of hypoattenuation on the baseline CT scans and the clinical outcome in the placebo-treated and the rt-PA-treated groups after 3 months was analyzed.

RESULTS

In 215 patients with a small hypoattenuating area, treatment increased the chance of good outcome. In 336 patients with a normal CT scan and in 52 patients with a large hypoattenuating area, rt-PA had no beneficial effect but increased the risk for fatal brain hemorrhage.

CONCLUSION

The response to rt-PA in patients with ischemic stroke can be predicted on the basis of initial CT findings of the extent of parenchymal hypoattenuation in the territory of the middle cerebral artery.

[Computer tomographic diagnosis of acute cerebral ischemmia]

Computed tomography (CT) is the first step in the radiological diagnostics of brain emergencies. We intend to study which pathophysiological changes are detected by CT and how CT contributes to prognosis and patient management in acute cerebral ischemia. We review recent publications about the role of CT in acute cerebral ischemia. Ischemic brain edema is associated with a decreased X-ray attenuation. Computed tomography is thus highly sensitive in detecting irreversibly damaged ischemic brain tissue. Patients showing large volumes of ischemic edema, exceeding one third of the middle cerebral artery territory, do not benefit from thrombolysis and have an increased risk of brain hemorrhage. The brain territory at risk from ischemia can be detected by CT angiography. To combine CT with CT angiography is a pragmatic approach which enables carefully directed treatment in acute cerebral ischemia.

Hemorrhagic transformation in acute ischemic stroke. Potential contributing factors in the European Cooperative Acute Stroke Study

BACKGROUND AND PURPOSE

Recent studies suggest that thrombolytic therapy may be of benefit to patients with acute ischemic stroke. However, the treatment also carries a significant risk of hemorrhagic transformation (HT). The purpose of this study was to select potential contributors to HT.

METHODS

We provide an explanatory analysis of the European Cooperative Acute Stroke Study (ECASS) data. ECASS was a multicenter, placebo-controlled, randomized trial of recombinant tissue plasminogen activator in ischemic stroke, within 6 hours of symptom onset, which enrolled 620 patients. HTs were classified into either hemorrhagic infarction or parenchymal hemorrhage according to their CT scan appearance. We used logistic regression analysis to select potential contributing factors to each type of HT.

RESULTS

The severity of initial clinical deficit (odds ratio [OR], 2.5; 95% confidence interval [CI], 1.6 to 4.0) and the presence of early ischemic changes on CT scan (OR, 3.5; 95% CI, 2.3 to 5.3) were associated with increased risk of hemorrhagic infarction. Increasing age (in decades; OR, 1.3; 95% CI, 1.0 to 1.7) and treatment with recombinant tissue plasminogen activator (OR, 3.6; 95% CI, 2.1 to 6.1) were related to the risk of parenchymal hemorrhage.

CONCLUSIONS

Since all potential contributing factors are readily discernible upon hospital admission, they should be used to improve selection of patients into future studies.

Potential of CT angiography in acute ischemic stroke

PURPOSE

To study the ability of CT angiography to show intracranial arterial occlusion and collateral blood flow in patients with acute stroke.

METHODS

Twenty-one patients with acute nonhemorrhagic stroke were studied prospectively with conventional CT, CT angiography, and digital subtraction angiography. On the basis of CT angiographic findings, two neuroradiologists independently assessed the site of arterial occlusion, the contrast enhancement in arterial branches beyond the occlusion as a measure of collateral blood supply, and the extent of diminished parenchymal enhancement; they then predicted the extent of ischemic infarction.

RESULTS

Both raters correctly assessed all trunk occlusions of the basilar artery (n = 4), the internal carotid artery (n = 4), and the middle cerebral artery (n = 9). The chance adjusted interrater agreement was kappa = .78. The assessment of branch occlusions of the middle cerebral artery was less reliable. The agreement rate in judging the collateral state in 17 occlusions in the anterior cerebral circulation was 88%. The size of 21 (62%) of 34 hemispheric infarctions was predicted correctly.

CONCLUSION

CT angiography quickly and reliably adds important information to conventional CT studies in cases of acute ischemic stroke. It shows the site of occlusion, the length of the occluded arterial segment, and the contrast-enhanced arteries beyond the occlusion as an estimate of collateral blood flow.

Coil placement after clipping: endovascular treatment of incompletely clipped cerebral aneurysms. Report of two cases

In up to 4% of patients whose aneurysms are microsurgically clipped, there is an expected or unexpected aneurysm residuum. The authors describe two patients in whom surgical clipping did not result in complete obliteration of the aneurysm sac and in whom a second operation was not believed to be the solution to the problem. In both patients complete occlusion of the aneurysm residuum was achieved via an endovascular approach. Using the Guglielmi detachable coil system, it was possible to place two platinum coils selectively into the aneurysms. The endovascular approach may be a good treatment option for all patients in whom surgical clipping does not result in complete obliteration of the aneurysm sac and reoperation is contraindicated or unacceptable to the patient.

Decompressive craniectomy in a rat model of "malignant" cerebral hemispheric stroke: experimental support for an aggressive therapeutic approach

Acute ischemia in the complete territory of the carotid artery may lead to massive cerebral edema with raised intracranial pressure and progression to coma and death due to uncal, cingulate, or tonsillar herniation. Although clinical data suggest that patients benefit from undergoing decompressive surgery for acute ischemia, little data about the effect of this procedure on experimental ischemia are available. In this article the authors present results of an experimental study on the effects of decompressive craniectomy performed at various time points after endovascular middle cerebral artery (MCA) occlusion in rats. Focal cerebral ischemia was induced in 68 rats using an endovascular occlusion technique focused on the MCA. Decompressive craniectomy was performed in 48 animals (in groups of 12 rats each) 4, 12, 24, or 36 hours after vessel occlusion. Twenty animals (control group) were not treated by decompressive craniectomy. The authors used the infarct volume and neurological performance at Day 7 as study endpoints. Although the mortality rate in the untreated group was 35%, none of the animals treated by decompressive craniectomy died (mortality 0%). Neurological behavior was significantly better in all animals treated by decompressive craniectomy, regardless of whether they were treated early or late. Neurological behavior and infarction size were significantly better in animals treated very early by decompressive craniectomy (4 hours) after endovascular MCA occlusion (p < 0.01); surgery performed at later time points did not significantly reduce infarction size. The results suggest that use of decompressive craniectomy in treating cerebral ischemia reduces mortality and significantly improves outcome. If performed early after vessel occlusion, it also significantly reduces infarction size. By performing decompressive craniectomy neurosurgeons will play a major role in the management of stroke patients.

Interobserver agreement in assessing early CT signs of middle cerebral artery infarction

PURPOSE

To assess the reliability of detecting signs of hemispheric infarction on CT scans obtained within 6 hours of the onset of symptoms.

METHODS

A neuroradiologist selected 12 normal and 33 abnormal CT studies showing the hyperdense middle cerebral artery sign (HMCAS) (n = 10), brain swelling (n = 22), and parenchymal hypodensity (n = 33) from two series of 750 patients with recent onset of middle cerebral artery stroke. These selections served as the reference source for a nonblinded analysis of the initial and follow-up CT scans. Six neuroradiologists then reviewed the CT scans twice, first blinded then not blinded to clinical symptoms. They assessed the signs of infarction for each hemisphere separately and estimated the volume of abnormal parenchymal hypodensity in increments of 20% within the territory of the middle cerebral artery.

RESULTS

Unblinding the reviewers did not change interobserver agreement significantly. The chance adjusted agreement was moderate to substantial: kappa = .62 (95% confidence interval [CI], .46 to .78) and kappa = .57 (95% CI, .33 to .81) for the HMCAS of the right and left hemisphere, respectively; kappa = .59 (95% CI, .47 to .71) and kappa = .56 (95% CI, .38 to .74) for focal brain swelling of the right and left hemisphere, respectively; and kappa = .58 (95% CI, .50 to .66) and kappa = .55 (95% CI, .32 to .67) for parenchymal hypodensity of the right and left hemisphere, respectively. Weighted kappa was .65 and .57 for the estimation of the hypodense tissue volume in the right and left hemisphere, respectively. Agreement with the reference source ranged from 73% to 93% for all variables and both hemispheres.

CONCLUSION

Even with no clinical information, neuroradiologists can assess subtle CT signs of cerebral infarction within the first 6 hours of symptom onset with moderate to substantial interobserver agreement.

[Neuroradiological studies and findings in stroke]

This overview is about today's radiologic diagnostic possibilities in acute stroke. Despite many improvements in MR technology, CT is still the method of choice for most of these patients. Contrary to a long existing opinion, CT is a good diagnostic instrument even in the early phase of acute ischemic stroke. In combination with the new helical CT technique [CT angiography] all important questions regarding early therapeutic decisions can be answered. New MR perfusion techniques are just on the way to clinical application. Invasive angiography is only rarely indicated in acute ischemic stroke. The diagnosis of intracerebral hemorrhage is also mainly CT-based. MR and DSA are mandatory for further evaluation of the etiology of the hemorrhage. Nowadays, DSA is not longer mandatory for the diagnosis of cerebral venous sinus thrombosis. In some patients CT is already diagnostic; the combination of different MR and MRA techniques nearly always allows a definite diagnosis or exclusion of a venous thrombosis.

[Reversible cerebral MRI findings in acute microangiopathic hemolytic anemia]

A case of acute microangiopathic hemolytic anemia in a 29-year-old primiparous patient is presented. Following an unsuspicuous pregnancy and uncomplicated delivery, the patient developed upper abdominal symptoms and transient psychopathologic abnormalities 2 days after delivery. Because of a series of generalized tonic-clonic seizures and respiratory distress she was admitted to the Neuro ICU. Focal neurological symptoms were absent, and CSF analysis was normal. Laboratory findings indicated hemolytic anemia with fragmented erythrocytes in smear specimens, thrombocytopenia, reticulocytosis, marked elevation of liver and pancreatic enzymes, and microhematuria. T2-weighted MR scans of the brain discluded multiple ischemic lesions of the cerebral white and gray matter, caudate nucleus and pons, displaying a hemodynamic pattern. Specific treatment included administration of corticosteroids, repeated plasmapheresis with substitution by fresh frozen plasma and antithrombin III. A control MR performed on the 3rd day of treatment demonstrated the absence of nearly all abnormal findings previously obtained. During a 3-week clinical course the patient showed full recovery, including normalization of hematologic and neuroradiologic findings. This case demonstrates ischemic cerebral lesions in acute microangiopathic hemolytic anemia to be potentially reversible if specific treatment is provided.

Thrombolytic therapy of acute basilar artery occlusion. Variables affecting recanalization and outcome

BACKGROUND AND PURPOSE

Thrombolysis may reduce mortality after acute basilar artery (BA) occlusion. We intended to find variables affecting recanalization and clinical outcome in patients with BA occlusion undergoing thrombolytic therapy.

METHODS

We analyzed in retrospect the clinical and angiographic data of a consecutive series of 51 patients treated with intra-arterial urokinase (n = 44; 0.3 to 1.5 mIU) or intravenous or intra-arterial recombinant tissue plasminogen activator (n = 7; 22 to 100 mg). We identified effective variables by multiple logistic regression analyses and univariate tests.

RESULTS

Sites of occlusion were the caudal (n = 23), middle (n = 18), and distal (n = 10) segments of the BA. The pathogenesis was embolism in 35 and local atherothrombosis in 16 patients. Collateral circulation was good in 32 patients and poor or absent in 19 patients. Recanalization was achieved in 26 of 51 (51%) patients and was associated with occlusions of embolic etiology (P = .0025). Mortality was 46% (12/26) in the recanalization group and 92% (23/25) in the nonrecanalization group (P = .0004). Other independent variables affecting mortality were length of BA obstruction (P = .0011), age (P = .0008), and collateral state (P = .0454). After follow-up (median, 32 months), 10 of the 16 survivors were only minimally impaired, with a Barthel Index score of 95 or greater; 5 patients were moderately and 1 severely disabled.

CONCLUSIONS

Recanalization of acute BA occlusion reduces mortality significantly. Length of BA obstruction and state of the collaterals are additional independent variables affecting survival. Young patients with monosegmental embolic occlusion of the BA seem to have the best chance to considerably profit from thrombolysis.