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  • 1
    Online Resource
    Online Resource
    Diffusion- and Perfusion-Weighted Imaging in Vasospasm After Subarachnoid Hemorrhage
    Ovid Technologies (Wolters Kluwer Health) ; 1999
    In:  Stroke Vol. 30, No. 3 ( 1999-03), p. 599-605
    Details
    In: Stroke, Ovid Technologies (Wolters Kluwer Health), Vol. 30, No. 3 ( 1999-03), p. 599-605
    Abstract: Background and Purpose —Better measures of cerebral tissue perfusion and earlier detection of ischemic injury are needed to guide therapy in subarachnoid hemorrhage (SAH) patients with vasospasm. We sought to identify tissue ischemia and early ischemic injury with combined diffusion-weighted (DW) and hemodynamically weighted (HW) MRI in patients with vasospasm after SAH. Methods —Combined DW and HW imaging was used to study 6 patients with clinical and angiographic vasospasm, 1 patient without clinical signs of vasospasm but with severe angiographic vasospasm, and 1 patient without angiographic spasm. Analysis of the passage of an intravenous contrast bolus through brain was used to construct multislice maps of relative cerebral blood volume (rCBV), relative cerebral blood flow (rCBF), and tissue mean transit time (tMTT). We hypothesize that large HW imaging (HWI) abnormalities would be present in treated patients at the time they develop neurological deficit due to vasospasm without matching DW imaging (DWI) abnormalities. Results —Small, sometimes multiple, ischemic lesions on DWI were seen encircled by a large area of decreased rCBF and increased tMTT in all patients with symptomatic vasospasm. Decreases in rCBV were not prominent. MRI hemodynamic abnormalities occurred in regions supplied by vessels with angiographic vasospasm or in their watershed territories. All patients with neurological deficit showed an area of abnormal tMTT much larger than the area of DWI abnormality. MRI images were normal in the asymptomatic patient with angiographic vasospasm and the patient with normal angiogram and no clinical signs of vasospasm. Conclusions —We conclude that DW/HW MRI in symptomatic vasospasm can detect widespread changes in tissue hemodynamics that encircle early foci of ischemic injury. With additional study, the technique could become a useful tool in the clinical management of patients with SAH.
    Type of Medium: Online Resource
    ISSN: 0039-2499 , 1524-4628
    URL: Article
    DOI: 10.1161/01.STR.30.3.599
    RVK:
    XA 10000
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 1999
    detail.hit.zdb_id: 1467823-8
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  • 2
    Online Resource
    Online Resource
    Role for Telemedicine in Acute Stroke : Feasibility and Reliability of Remote Administration of the NIH Stroke Scale
    Ovid Technologies (Wolters Kluwer Health) ; 1999
    In:  Stroke Vol. 30, No. 10 ( 1999-10), p. 2141-2145
    Details
    In: Stroke, Ovid Technologies (Wolters Kluwer Health), Vol. 30, No. 10 ( 1999-10), p. 2141-2145
    Abstract: Background and Purpose —Immediate access to physicians experienced in acute stroke treatment may improve clinical outcomes in patients with acute stroke. Interactive telemedicine can make stroke specialists available to assist in the evaluation of patients at multiple urban or remote rural facilities. We tested whether interrater agreement for the NIH Stroke Scale (NIHSS), a critical component of acute stroke assessment, would persist if performed over a telemedicine link. Methods —One bedside and 1 remote NIHSS score were independently obtained on each of 20 patients with ischemic stroke. The bedside examination was performed by a stroke neurologist at the patient’s bedside. The remote examination was performed by a second stroke neurologist through an interactive high-speed audio-video link, assisted by a nurse at the patient’s bedside. Kappa coefficients were calculated for concordance between bedside and remote scores. Results —Remote assessments took slightly longer than bedside assessments (mean 9.70 versus 6.55 minutes, P 〈 0.001). NIHSS scores ranged from 1 through 24. Based on weighted κ coefficients, 4 items (orientation, motor arm, motor leg, and neglect) displayed excellent agreement, 6 items (language, dysarthria, sensation, visual fields, facial palsy, and gaze) displayed good agreement, and 2 items (commands and ataxia) displayed poor agreement. Total NIHSS scores obtained by bedside and remote methods were strongly correlated ( r =0.97, P 〈 0.001). Conclusions —The NIH Stroke Scale remains a swift and reliable clinical instrument when used over interactive video. Application of this technology can bring stroke expertise to the bedside, regardless of patient location.
    Type of Medium: Online Resource
    ISSN: 0039-2499 , 1524-4628
    URL: Article
    DOI: 10.1161/01.STR.30.10.2141
    RVK:
    XA 10000
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 1999
    detail.hit.zdb_id: 1467823-8
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  • 3
    Online Resource
    Online Resource
    Diffusion-weighted MR Imaging: Diagnostic Accuracy in Patients Imaged within 6 Hours of Stroke Symptom Onset
    Radiological Society of North America (RSNA) ; 1999
    In:  Radiology Vol. 210, No. 1 ( 1999-01), p. 155-162
    Details
    In: Radiology, Radiological Society of North America (RSNA), Vol. 210, No. 1 ( 1999-01), p. 155-162
    Type of Medium: Online Resource
    ISSN: 0033-8419 , 1527-1315
    URL: Article
    DOI: 10.1148/radiology.210.1.r99ja02155
    RVK:
    XA 10000
    Language: English
    Publisher: Radiological Society of North America (RSNA)
    Publication Date: 1999
    detail.hit.zdb_id: 80324-8
    detail.hit.zdb_id: 2010588-5
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  • 4
    Online Resource
    Online Resource
    Time Course of Lesion Development in Patients With Acute Stroke : Serial Diffusion- and Hemodynamic-Weighted Magnetic Resonance Imaging
    Ovid Technologies (Wolters Kluwer Health) ; 1998
    In:  Stroke Vol. 29, No. 11 ( 1998-11), p. 2268-2276
    Details
    In: Stroke, Ovid Technologies (Wolters Kluwer Health), Vol. 29, No. 11 ( 1998-11), p. 2268-2276
    Abstract: Background and Purpose —We sought to characterize the evolution of acute ischemic stroke by MRI and its relationship to patients’ neurological outcome. Methods —Fourteen patients with acute ischemic stroke underwent MRI within 13 hours of symptom onset (mean, 7.4±3 hours) and underwent repeated imaging and concurrent neurological examination at 8, 24, 36, and 48 hours and 7 days and 〉 42 days after first imaging. Results —Diffusion-weighted imaging (DWI) lesion volumes increased between the first and second scans in 10 of 14 patients; scans with maximum DWI lesion volume occurred at a mean of 70.4 hours. Initial DWI lesion volume correlated with the largest T2 lesion volume ( r =0.97; P 〈 0.001). Final lesion volume was smaller than maximum lesion volume in 12 of 14 patients. There was positive correlation between the follow-up National Institutes of Health Stroke Scale score and the initial DWI lesion volume ( r =0.67; P =0.01) and maximum T2 lesion volume ( r =0.77; P 〈 0.01) and negative correlation with initial mean apparent diffusion coefficient ratio (ADCr) ( r =−0.64; P 〈 0.05). The ADCr was 0.73 at initial imaging and fell between the initial and second scans in 10 of 14 patients. Mean ADCr did not rise above normal until 42 days after stroke onset ( P 〈 0.001). Conclusions —Serial MRI demonstrates the dynamic nature of progressive ischemic injury in acute stroke patients developing over hours to days, and it suggests that both primary and secondary pathophysiological processes can be valuable targets for neuroprotective interventions.
    Type of Medium: Online Resource
    ISSN: 0039-2499 , 1524-4628
    URL: Article
    DOI: 10.1161/01.STR.29.11.2268
    RVK:
    XA 10000
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 1998
    detail.hit.zdb_id: 1467823-8
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  • 5
    Online Resource
    Online Resource
    Diffusion-Weighted Imaging Discriminates Between Cytotoxic and Vasogenic Edema in a Patient With Eclampsia
    Ovid Technologies (Wolters Kluwer Health) ; 1997
    In:  Stroke Vol. 28, No. 5 ( 1997-05), p. 1082-1085
    Details
    In: Stroke, Ovid Technologies (Wolters Kluwer Health), Vol. 28, No. 5 ( 1997-05), p. 1082-1085
    Abstract: Background The pathophysiology of eclampsia remains unclear. While the majority of patients develop reversible T2 hyperintense signal abnormalities on MR scans and reversible neurological deficits, some patients do develop infarctions (permanent T2 hyperintense abnormalities) and permanent neurological impairment. Routine MRI cannot prospectively differentiate between these two patient groups. Echo-planar diffusion-weighted imaging, however, is a new technique that clearly differentiates between cytotoxic and vasogenic edema. Case Description A 30-year-old woman developed symptoms consistent with eclampsia 24 hours after delivering premature twins. An MRI demonstrated extensive, diffuse T2 hyperintense signal abnormalities involving subcortical white matter and adjacent gray matter with a posterior predominance, consistent with either infarction or hypertensive ischemic encephalopathy. Diffusion-weighted images demonstrated increased diffusion, consistent with vasogenic edema and hypertensive ischemic encephalopathy. Conclusions Unlike routine MRI, diffusion-weighted imaging reliably differentiates between vasogenic edema and cytotoxic edema. Consequently, in eclamptic patients diffusion-weighted imaging can afford clear differentiation between hypertensive ischemic encephalopathy and infarction, two very different entities with very different treatment protocols. Diffusion-weighted imaging should be performed in all eclamptic patients and should greatly affect their management.
    Type of Medium: Online Resource
    ISSN: 0039-2499 , 1524-4628
    URL: Article
    DOI: 10.1161/01.STR.28.5.1082
    RVK:
    XA 10000
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 1997
    detail.hit.zdb_id: 1467823-8
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  • 6
    Online Resource
    Online Resource
    Pharmacological Elevation of Blood Pressure in Acute Stroke : Clinical Effects and Safety
    Ovid Technologies (Wolters Kluwer Health) ; 1997
    In:  Stroke Vol. 28, No. 11 ( 1997-11), p. 2133-2138
    Details
    In: Stroke, Ovid Technologies (Wolters Kluwer Health), Vol. 28, No. 11 ( 1997-11), p. 2133-2138
    Abstract: Background and Purpose Lowering of blood pressure can adversely affect ischemic symptoms in acute stroke. The aim of our study was to determine whether induced hypertension in stroke is safe and to examine its effects on neurological deficits in patients presenting with acute cerebral ischemia. Methods We retrospectively reviewed all patients admitted to our neurological intensive care unit with the diagnosis of ischemic stroke over a 2.5-year period. Thirty-three patients were not given a pressor agent (Ph− group), while 30 were treated with phenylephrine (Ph+ group) in an attempt to improve cerebral perfusion. Results Baseline characteristics showed few differences between the Ph+ and Ph− groups. Intracerebral hemorrhage, brain edema, cardiac morbidity, and mortality were not increased in the Ph+ group. In 10 of 30 Ph+ patients, a systolic blood pressure threshold was identified below which ischemic deficits worsened and above which deficits improved. The mean threshold was 156 mm Hg (range, 120 to 190 mm Hg). The mean number of stenotic/occluded cerebral arteries was greater in those Ph+ patients with an identified clinical blood pressure threshold (mean, 2.1 per patient) than in Ph+ patients without a threshold (mean, 1.2 per patient; P 〈 .05). Conclusions The results suggest that careful use of phenylephrine-induced hypertension is not associated with an increase in morbidity or mortality in acute stroke. Although based on a retrospective analysis of clinical practice, this report suggests that a subset of patients, particularly those with multiple stenosis of cerebral arteries, may improve neurologically upon elevation of the blood pressure.
    Type of Medium: Online Resource
    ISSN: 0039-2499 , 1524-4628
    URL: Article
    DOI: 10.1161/01.STR.28.11.2133
    RVK:
    XA 10000
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 1997
    detail.hit.zdb_id: 1467823-8
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  • 7
    Online Resource
    Online Resource
    Diffusion-Weighted Imaging Identifies a Subset of Lacunar Infarction Associated With Embolic Source
    Ovid Technologies (Wolters Kluwer Health) ; 1999
    In:  Stroke Vol. 30, No. 12 ( 1999-12), p. 2644-2650
    Details
    In: Stroke, Ovid Technologies (Wolters Kluwer Health), Vol. 30, No. 12 ( 1999-12), p. 2644-2650
    Abstract: Background and Purpose —Small infarcts in the territory of penetrator arteries were described as causing a number of distinct clinical syndromes. The vascular pathophysiology underlying such infarcts is difficult to ascertain without careful pathological study. However, the occurrence of multiple, small infarcts, linked closely in time but dispersed widely in the brain, raises the possibility of an embolic mechanism. The current study determines the frequency and clinical characteristics of patients with well-defined lacunar syndromes and the diffusion-weighted imaging (DWI) evidence of multiple acute lesions. Methods —Sixty-two consecutive patients who presented to the emergency room with a clinically well-defined lacunar syndrome were studied by DWI within the first 3 days of admission. Results —DWI showed multiple regions of increased signal intensity in 10 patients (16%). A hemispheric or brain stem lesion in a penetrator territory that accounted for the clinical syndrome (“index lesion”) was found in all. DWI-hyperintense lesions other than the index lesion (“subsidiary infarctions”) were punctate and lay within leptomeningeal artery territories in the majority. As opposed to patients with a single lacunar infarction, patients with a subsidiary infarction more frequently ( P 〈 0.05) harbored an identifiable cause of stroke. Conclusions —Almost 1 of every 6 patients presenting with a classic lacunar syndrome has multiple infarctions demonstrated on DWI. This DWI finding usually indicates an identifiable cause of stroke and therefore may influence clinical decisions regarding the extent of etiologic investigations and treatment for secondary prevention.
    Type of Medium: Online Resource
    ISSN: 0039-2499 , 1524-4628
    URL: Article
    DOI: 10.1161/01.STR.30.12.2644
    RVK:
    XA 10000
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 1999
    detail.hit.zdb_id: 1467823-8
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  • 8
    Online Resource
    Online Resource
    Regional Ischemia and Ischemic Injury in Patients With Acute Middle Cerebral Artery Stroke as Defined by Early Diffusion-Weighted and Perfusion-Weighted MRI
    Ovid Technologies (Wolters Kluwer Health) ; 1998
    In:  Stroke Vol. 29, No. 5 ( 1998-05), p. 939-943
    Details
    In: Stroke, Ovid Technologies (Wolters Kluwer Health), Vol. 29, No. 5 ( 1998-05), p. 939-943
    Abstract: Background and Purpose —We sought to map early regional ischemia and infarction in patients with middle cerebral artery (MCA) stroke and compare them with final infarct size using advanced MRI techniques. MRI can now delineate very early infarction by diffusion-weighted imaging (DWI) and abnormal tissue perfusion by perfusion-weighted imaging (PWI). Methods —Seventeen patients seen within 12 hours of onset of MCA stroke had MR angiography, standard MRI, and PWI and DWI MRI. PWI maps were generated by analysis of the passage of intravenous contrast bolus through the brain. Cerebral blood volume (CBV) was determined after quantitative analysis of PWI data. Volumes of the initial DWI and PWI lesion were calculated and compared with a final infarct volume from a follow-up imaging study (CT scan or MRI). Results —Group 1 (10 patients) had MCA stem (M1) occlusion by MR angiography. DWI lesion volumes were smaller than the volumes of CBV abnormality. In 7 patients the final stroke volume was larger or the same, and in 3 it was smaller than the initial CBV lesion. Group 2 (7 patients) had an open M1 on MR angiography with distal MCA stroke. In 6 group 2 patients, the initial DWI lesion matched the initial CBV abnormality and the final infarct. Conclusions —Most patients with M1 occlusion showed progression of infarction into the region of abnormal perfusion. In contrast, patients with open M1 had strokes consistent with distal branch occlusion and had maximal extent of injury on DWI at initial presentation. Application of these MRI techniques should improve definition of different acute stroke syndromes and facilitate clinical decision making.
    Type of Medium: Online Resource
    ISSN: 0039-2499 , 1524-4628
    URL: Article
    DOI: 10.1161/01.STR.29.5.939
    RVK:
    XA 10000
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 1998
    detail.hit.zdb_id: 1467823-8
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  • 9
    Online Resource
    Online Resource
    Hyperacute Stroke: Simultaneous Measurement of Relative Cerebral Blood Volume, Relative Cerebral Blood Flow, and Mean Tissue Transit Time
    Radiological Society of North America (RSNA) ; 1999
    In:  Radiology Vol. 210, No. 2 ( 1999-02), p. 519-527
    Details
    In: Radiology, Radiological Society of North America (RSNA), Vol. 210, No. 2 ( 1999-02), p. 519-527
    Type of Medium: Online Resource
    ISSN: 0033-8419 , 1527-1315
    URL: Article
    DOI: 10.1148/radiology.210.2.r99fe06519
    RVK:
    XA 10000
    Language: English
    Publisher: Radiological Society of North America (RSNA)
    Publication Date: 1999
    detail.hit.zdb_id: 80324-8
    detail.hit.zdb_id: 2010588-5
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