Mechanisms of single and multiple borderzone infarct: transcranial Doppler ultrasound/magnetic resonance imaging correlates.

BACKGROUND AND PURPOSE: Hemodynamic patterns after borderzone (BZ) infarction are variable and dynamic. However, stroke mechanisms in different types of BZ infarctions have not been systematically studied by magnetic resonance angiography (MRA) and transcranial Doppler ultrasonography (TCD). METHODS: Forty-nine patients who experienced a stroke limited to the territory of either the superficial or internal borderzone proved on MRI included in our registry, corresponding to 4% of 1,200 patients with ischemic stroke, were studied. All these patients underwent MRA, extracranial Doppler ultrasonography, TCD and other investigations from the standard protocol of our registry. Twenty of them (41%) had a posterior BZ infarct, 14 (29%) an anterior BZ infarct, 10 (20%) a subcortical BZ infarct and 5 (10%) bilateral BZ infarcts. RESULTS: Unilateral internal carotid artery (ICA) tight stenosis or occlusion ipsilateral to the lesion was present in 14 patients (70%) with a posterior BZ infarct, in 72% of those with an anterior BZ infarct, in 80% of those with a subcortical BZ infarct and in 80% of those with bilateral BZ infarcts. TCD showed cross-filling of the middle cerebral artery via the anterior communicating artery in 5 patients (25%) with a posterior BZ infarct and 10% had an increased mean flow velocity (MFV) in the ipsilateral P1 posterior cerebral artery (PCA). In patients with an anterior BZ infarct, 3 (23%) had an MFV increase in the contralateral A1 anterior cerebral artery (ACA), and 2 (15%) had a higher MFV in the ipsilateral PCA. An elevated velocity at midline depths with reversed A1 ACA flow direction was seen in 2 patients (20%) with a subcortical infarct, and 1 patient (10%) had an MFV increase in the ipsilateral P1 PCA. Left ventricular systolic dysfunction (ejection fraction <40%) was present in 50% of patients with a posterior BZ infarct, in 36% of those with an anterior BZ infarct, in 20% of those with a subcortical BZ infarct and bilateral BZ infarcts each. CONCLUSION: The association of severe ICA stenosis or occlusion with cardiopathies and left ventricular dysfunction may play a critical role in those with BZ infarcts having inadequate collateral supply, while a cardioembolism or acute ICA dissection may also cause BZ infarction due to the rapidity of the occlusive process and the inability of the cerebral vasculature to recruit collateral pathways quickly enough.

Spectrum of single and multiple corona radiata infarcts: clinical/MRI correlations.

We sought to determine the clinical pictures, topography and pathogenesis of patients with unilateral single or multiple corona radiata infarcts. We defined corona radiata ischemic stroke if the patient had a focal neurological deficit and a relevant non-hemorrhagic infarction confined to the vascular territory of a long medullary artery proved by CT and MRI with contrast. We compared risk factors and clinical feature between subtypes of corona radiata infarcts. The study sample represents 1.2% of the patients (68/5500) with first-ever stroke in our Registry, including ischemic and hemorrhagic strokes. There were 37 patients (54%) with single infarct presenting 17 different complete or partial sensory-motor symptoms with dysarthria; 14 patients (21%) with unilateral multiple infarcts in one hemisphere had often complete sensorimotor deficits with some neuropsychological impairment; among 17 patients (25%) with multiple infarcts in both hemisphere, one half had bilateral motor and sensory symptoms, and neuropsychological deficits, visual field defects were uncommon. Seventeen patients (25%) had dysarthria, which was no localizing value. Hypertension was the most frequent vascular risk factor in 62% of patients, smoking in 28%, diabetes mellitus in 26%, hypercholesterolemia in 9%, and atrial fibrillation in 7%. The main cause of corona radiata infarcts was small-artery disease with long-standing hypertension in 40 patients (59%), large-artery disease in 19%, cardioembolism in 12%. Most of the patients (88%) had leukoaraiosis, and patients with bilateral multiple infarcts, leukoaraiosis was more frequent than in those with unilateral single infarct (P = .016; < .05). Despite clinical similarity to that found in superficial and deep infarcts, incomplete motor and sensory symptoms and MRI allows to delineate simultaneous uni- or multiple infarcts in the corona radiata. After an acute and immediate onset, outcome at 6 months of stroke onset is in general benign except those with bilateral infarcts. The coexistence of small-artery disease with leukoaraiosis suggest similar vascular risk factors and physiopathological mechanism.

Mesencephalic and associated posterior circulation infarcts.

BACKGROUND AND PURPOSE: The purposes of this study were to evaluate and review the risk factors and clinical features of patients with posterior circulation stroke involving mesencephalon and neighboring structures and to describe the clinical syndromes according to the mesencephalic arterial territory involved. METHODS: We studied all patients with acute posterior circulation stroke involving mesencephalon who were admitted consecutively to our stroke unit over a 6-year period. We selected these patients (3%) from 1296 patients with posterior circulation infarct. Neurological and radiological investigations, including MRI and angiography, were performed in all cases. We classified patients into 4 groups on the basis of MRI findings: (1) isolated mesencephalic infarcts (9 patients); (2) distal territory infarcts (19 patients), including mesencephalon, thalamus, medial temporal and occipital lobes, and cerebellum; (3) middle territory infarcts (12 patients), including the pons and anterior inferior cerebellar artery territory; and (4) proximal territory infarcts (1 patient), including the medulla and posterior inferior cerebellar artery territory. RESULTS: Middle mesencephalon involvement was the most common in all groups, and the anteromedial territory was frequently affected, depending on the direct perforators of basilar artery. In patients with isolated mesencephalic infarct, the clinical picture was dominated by nuclear or fascicular third-nerve palsy and contralateral motor deficits. The distal territory involvement was the most common and associated with consciousness disturbances, gait ataxia, ocular motor disturbances, and visual field deficits. The neurological picture of middle territory infarcts was dominated by consciousness disturbances with dysarthria, horizontal ocular motor disorders, and hemiparesis. Proximal territory involvement was rare and associated with acute unsteadiness, vertigo, dysphagia, dysphonia, tetra-ataxia, and motor weakness. The most common cause of stroke was large-artery disease in 16 patients (39%), cardioembolism in 8 (20%), and small-artery disease with lacunar mesencephalic infarct in 10 (24%). Bilateral mesencephalic infarcts were not uncommon (27%), mainly in patients with multiple and extended infarcts in the posterior circulation, and were associated with poor outcome compared with unilateral infarct. CONCLUSIONS: Our study highlights the topographic and clinical heterogeneity of the acute posterior circulation infarcts involving mesencephalon. The variety of the underlying potential causes of stroke requires detailed investigations of the extra and intracranial arteries and the heart.

Clinical spectrum of pontine infarction. Clinical-MRI correlations.

We sought clinical and radiological findings of 150 consecutive patients with acute isolated pontine infarct who were admitted to our Stroke Unit over 6 years. In all patients CT, MRI and magnetic resonance angiography (MRA) were performed during the hospitalization. On clinico-radiological analysis regarding the pontine lesion boundaries there were five main clinical patterns that depended on the constant territories of intrinsic pontine arteries: (1). anteromedial pontine syndrome (58%) presented with motor deficit with dysarthria, ataxia, and mild tegmental signs in one third of patients; (2). anterolateral pontine syndrome (17%) developed with motor and sensory deficits in half of the patients, and were associated with tegmental signs (56%) more frequently than the anteromedial infarct syndrome; (3). tegmental pontine syndrome (10%) presented with mild motor deficits and associated with sensory syndromes, eye movement disorders and vestibular system symptoms including vertigo, dizziness and ataxia; (4). bilateral pontine syndrome (11%) consisted with transient consciousness loss, tetraparesis and acute pseudobulbar palsy; (5). unilateral multiple pontine infarcts (4%) were rarely observed, and were always associated with severe sensory-motor deficits and tegmental signs. In our series, there was no infarct in the extreme dorsal and lateral tegmental pontine territories which have been mostly associated with cerebellar infarctions. The main etiology of stroke was basilar artery branch disease (BABD) in 59 patients (39%), followed by small-artery disease (SAD) in 31 (21%), large-artery disease of vertebrobasilar arteries in 27 patients (18%), cardioembolism in 12 (8%) and in 16 patients (11%) no cause of stroke was found. Our findings suggest that it is possible to identify clinical subgroups of pontine infarction, in which BABD and SAD were the most common causes of stroke. After an acute onset, outcome is in general excellent except in those with bilateral pontine lesions.