Advances in the genetics of cerebrovascular disease and stroke.

MEDLINE searches identified epidemiologic, experimental, and clinical studies on the genetics of cerebrovascular disease and stroke, including the following topics: genetic epidemiology of stroke; genetics of systemic disorders that cause ischemic stroke, including coagulation disorders, connective tissue disorders, vasculopathies, metabolic disorders, and disorders of unknown etiology; and genetics of systemic disorders that cause hemorrhagic stroke. Recent discoveries in stroke genetics involve the genetic basis of monogenic disorders such as cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy and sickle cell disease. Reproducing similar advances in other forms of cerebrovascular disease and stroke will be more difficult because their inheritance is complex, multigenic, and heterogeneous. However, the future is promising with the application of molecular genetic approaches such as linkage analysis, allele-sharing methods, association studies, and polygenic analysis of experimental crosses as well as the transmission/disequilibrium test--a statistical method for detection of linkage between a marker and a disease-susceptibility locus.

Recommendations for the establishment of primary stroke centers. Brain Attack Coalition.

OBJECTIVE: To develop recommendations for the establishment and operation of primary stroke centers as an approach to improve the medical care of patients with stroke. PARTICIPANTS: Members of the Brain Attack Coalition (BAC), a multidisciplinary group of representatives from major professional organizations involved with delivering stroke care. Supplemental input was obtained from other experts involved in acute stroke care. EVIDENCE: A review of literature published from 1966 to March 2000 was performed using MEDLINE. More than 600 English-language articles that had evidence from randomized clinical trials, meta-analyses, care guidelines, or other appropriate methods supporting specific care recommendations for patients with acute stroke that could be incorporated into a stroke center model were selected. CONSENSUS PROCESS: Articles were reviewed initially by 1 author (M.J.A.). Members of the BAC reviewed each recommendation in the context of current practice parameters, with special attention to improving the delivery of care to patients with acute stroke, cost-effectiveness, and logistical issues related to the establishment of primary stroke centers. Consensus was reached among all BAC participants before an element was added to the list of recommendations. CONCLUSIONS: Randomized clinical trials and observational studies suggest that several elements of a stroke center would improve patient care and outcomes. Key elements of primary stroke centers include acute stroke teams, stroke units, written care protocols, and an integrated emergency response system. Important support services include availability and interpretation of computed tomography scans 24 hours everyday and rapid laboratory testing. Administrative support, strong leadership, and continuing education are also important elements for stroke centers. Adoption of these recommendations may increase the use of appropriate diagnostic and therapeutic modalities and reduce peristroke complications. The establishment of primary stroke centers has the potential to improve the care of patients with stroke. JAMA. 2000.

[Non-invasive evaluation of extracranial and intracranial vascular disease]. / Diagnóstico no invasivo de la enfermedad vascular extra e intracraneal.

INTRODUCTION: Over the last 10 years the diagnosis of chronic and acute cerebrovascular disorders has been greatly improved. We have available now not only better anatomical imaging methods that allow a more precise localization and subtyping of the problem, but also physiological methods that look at the function and interaction between the brain's parenchyma and its perfusion. DEVELOPMENT: In this article the utility and clinical indications of ultrasonography (duplex and Transcranial Doppler) including the modern techniques of embolus detection are described. Also discussed are Magnetic resonance angiography, perfusion-diffusion magnetic resonance, computed tomographic angiography (angio-CT), single photon emission tomography (SPECT). Clinical examples of real cases exemplify the use of these techniques.

The American Society of Neuroradiology. Neuroradiology research: the opportunities and the challenges.

The next decade will witness an explosion of research and development in the neurosciences. The imaging of physiologic and functional processes--the frontier today--will become the norm. There are huge populations of patients with neurodegenerative and cerebrovascular diseases that require nonanatomic diagnostic evaluation. Radiologists must cease being just readers of morphologic images. They must broaden their scope and their areas of expertise. Imaging-guided therapy of all forms will alter the types of interventions we perform on patients. These new techniques will increase the efficacy of neuro-interventions while decreasing their morbidity and mortality. Resources, both human and financial, will be conserved. Radiologists can participate in this wonderful future if they broaden their training. Information management and the use of imaging for procedural guidance are the bases of our profession, but we are weak in the clinical applications of the technology. We must realize that our clinical colleagues are poised to assume the leadership in imaging research and development and in its performance. The challenge to the leaders of radiology is quite apparent: the recognition of the need to train for the future with the most open of minds and the least rigidity. This requires that we all understand the depth of the merger between the imaging and the clinical sciences that is occurring and that will increase substantially in the future. We must be the leaders in such a merger; otherwise, we will not be participants.

Three-dimensional vascular reconstruction with a clinical x-ray angiography system.

RATIONALE AND OBJECTIVES: The authors developed a technique to produce high-resolution, three-dimensional images of vasculature from a set of x-ray projections in an attempt to provide detailed anatomic representations of complex vasculature. MATERIALS AND METHODS: Projection images were acquired with a clinical angiographic system by using biplanar rotational digital subtraction angiography. The images were reconstructed with an additive algebraic reconstruction technique. RESULTS: The feasibility of the technique was tested by reconstructing three-dimensional images of several phantoms, including a wire phantom and an anatomic flow phantom. The anatomic phantom allowed replication of contrast material flow and image noise that are characteristic of patient examinations. The reconstruction procedure was then used to examine a carotid artery and a cerebral aneurysm in two patients. CONCLUSION: A method of reconstructing vasculature from x-ray angiograms has been developed and validated with geometric and anatomic phantoms. Preliminary patient applications indicate that this technique enables enhanced visualization of complex vascular relationships and structures.

The role of CT following aneurysmal rupture.

Computed tomography is a highly effective method of detecting subarachnoid blood if performed early after aneurysmal rupture, being 95% to 98% positive when lumbar puncture is positive. The localization of the blood defines the location of the aneurysm in approximately 80% of cases. Contrast enhanced computed tomography demonstrates the aneurysm in 75% of cases with the aneurysm is greater than 5 millimeters in size. Computed tomography angiography defines the aneurysm in up to 96% of cases. The amount of subarachnoid blood correlates with the development of vasospasm; cerebral perfusion can be further evaluated with xenon-enhanced computed tomography.

Brain attack. Introduction.

In today's medical community, the term "brain attack" is used in two ways. It is used as a synonym for stroke, and also as a reference to an educational and logistic campaign aimed at earlier recognition and treatment of stroke. This article presents an introduction to both uses of the phrase "brain attack," and focuses on the need for a brain attack campaign.

Functional MR imaging in the evaluation of the patient with epilepsy. Functional localization.

Functional magnetic resonance imaging is able to define noninvasively the location of eloquent cortex responsible for speech, motor, and visual function, and it holds promise for localizing other important functional tissues in the future. Such localization is extremely important to the epileptologist and surgeon planning surgical resection of an epileptic focus. Early work identifies the actual seizure focus using similar techniques. Magnetic resonance, with functional magnetic resonance added to high-resolution magnetic resonance imaging and magnetic resonance spectroscopy, has the potential of providing, in a cost-effective manner with one noninvasive modality, the functional, anatomic, and chemical parameters pertinent to the management of the seizure patient.

Functional magnetic resonance imaging as a management tool for cerebral arteriovenous malformations.

The location of eloquent cortex, such as the motor strip, the visual cortex, or Broca's area, may be difficult to predict even with multiprojectional magnetic resonance imaging (MRI). Distortion and displacement of this cortex may occur with a congenital lesion, such as an arteriovenous malformation, or by an acquired disease, such as a neoplasm. A desire to avoid damaging these eloquent areas by conventional surgery, radiosurgery, or endovascular surgery makes their accurate identification an important part of the pretherapeutic planning process. Blood oxygen level dependent functional MRI is a technique that uses the local increase of oxyhemoglobin concentration in the patient that occurs as a result of the increase in flow rate and blood volume in eloquent cortex undergoing stimulation from, for example, flashing lights, hand movements, or speech. We have used the blood oxygen level dependent technique to localize eloquent cortex relative to arteriovenous malformations and tumors. Using a 4.0-T magnetic resonance (MR) system, there is a sufficiently high degree of spatial resolution of the MR signal intensity changes during stimulation to allow the identification of eloquent cortex. Alternative, non-MR, invasive techniques for functional localization include electrocorticography and stimulation from subdural grids and strips. Noninvasive, non-MR technologies, such as positron emission tomography and magnetoencephalography, can also provide functional localization of eloquent cortex. However, the perfection of functional MRI at the 1.5-T field strength and the large number of such MR systems in operation mean that a highly accurate cerebral cortical localization technique can be available to most neuroscientists without the need to purchase alternative expensive technology.

Meningeal sarcoma mimicking an acute subdural hematoma on CT.

A case of meningeal sarcoma arising at the site of a prior subdural hematoma and mimicking an acute subdural hematoma on noncontrast CT is presented. The potential confusion between a hyperdense, nonhemorrhagic lesion and a hematoma on CT is highlighted. This report also reviews the possible relationship between meningeal injury and subsequent neoplastic change.

Cyclosporine A toxicity presenting with acute cerebellar edema and brainstem compression. Case report.

A 38-year-old man receiving cyclosporine A after bilateral lung transplantation for cystic fibrosis presented with cortical blindness, generalized seizures, and cerebellar edema. Progressive brainstem compression necessitated emergency posterior fossa decompression. Replacement of cyclosporine A with an alternative immunosuppressive agent, FK506, was followed by rapid neurological recovery and dramatic resolution of radiographic abnormalities. The etiology, clinical features, and radiographic findings of cyclosporine A neurotoxicity are discussed. The pertinent literature is reviewed.

Functional MR imaging of perceptual and cognitive functions.

Functional MR imaging using the blood oxygen level dependent technique as an endogenous contrast agent localizes eloquent cortex when stimulated by a variety of motor or sensory tasks. To date, visual, motor, speech, and cerebellar studies have been conducted, revealing significant information regarding cortical localization and control of various functions. The technique is also an important management tool for localizing eloquent cortex contiguous to a tumor or arteriovenous malformation, so that injury can be avoided if ablation of the lesion is contemplated.

Intra-aortic balloon counterpulsation augments cerebral blood flow in a canine model of subarachnoid hemorrhage-induced cerebral vasospasm.

We tested the effect of intra-aortic balloon counterpulsation (IABC) on cerebral blood flow (CBF) in a canine model of cerebral vasospasm. Cerebral vasospasm was induced in ten adult mongrel dogs using a "two-hemorrhage" model. CBF was then measured using radiolabeled microspheres, before and after activation of an intra-aortic balloon pump. Physiologic parameters including pCO2 and cardiac filling pressures were maintained constant during the experiment. Cardiac output was monitored in each animal. CBF increased with IABC in all ten animals. The mean CBF was 78.5 milliliters per 100 grams per minute (ml/100g/min) before versus 93.3ml/100g/min after IABC (P = 0.0001). Increases in CBF were associated in most, but not all, cases with increases in cardiac output. This study supports the ability of IABC to raise CBF in the setting of cerebral vasospasm. IABC may represent an important clinical option in cases of refractory vasospasm following aneurysmal subarachnoid hemorrhage.

Imaging of perinatal hypoxic-ischemic brain injury.

This article reviews some physiological parameters that influence the location and degree of injury from hypoxia-ischemia. The ability of various imaging tests, particularly magnetic resonance imaging, to detect tissue changes after hypoxia-ischemia is discussed. Most importantly, we evaluate the extent of our knowledge regarding the correlations between imaging, pathophysiological processes, and clinical medicine.