Immunosuppressive DrugInduced Vasculopathy
Cyclosporine, tacrolimus FK506 and interferon-a are effective immunosuppressive agents for the treatment of organ transplant rejection. Previous theories regarding the mechanism of neurotoxicity include neuropeptide-mediated ischemia and high-pressure failure of cerebral autoregulation 42 . Neurotoxicity usually coexists with hypertensive crisis however, it also occurs in normotensive individuals. These drugs have profound effects directly on the endothelium and cause release of potent...
PreeclampsiaEclampsia
Preeclampsia is characterized by hypertension, abnormal peripheral edema, and proteinuria that can progress to eclampsia, which also involves seizures. Although CNS changes in severe preeclampsia and eclampsia represent a form of hypertensive en-cephalopathy, they also occur in normotensive individuals. The precise pathogenesis remains unclear. However, endothelial dysfunction due to circulating endothelial toxins or antibodies against the endothe- lium can be the primary cause 38 . MR findings...
Posterior Reversible Encephalopathy Syndrome
Posterior reversible encephalopathy syndrome is a remarkably heterogeneous group of disorders, related to hypertensive encephalopathy, severe preeclampsia eclampsia, immunosuppressive drug or interferon neurotoxicity, uremia and thrombotic thrombocytopenic purpura 33 . The clinical symptoms are headache, altered mental status, seizures and visual loss. Posterior reversible encephalopathy syndrome is due to dysfunction of a cerebrovascular autoregulatory system, and a vasculopathy of small...
Uremic Encephalopathy and Hemolytic Uremic Syndrome
Uremic encephalopathy is the name given to a brain syndrome that occurs in patients with renal failure. The pathogenesis is unknown, but it has been hypothesized that it may be caused by various toxins associated with uremia elevated parathyroid hormone level, hypercalcemia, and other metabolic abnormal ities 44 . MR imaging usually shows reversible bilateral symmetric white matter lesions. The lesions can also involve the basal ganglia or cortex. DW imaging usually shows iso- or slightly...
Hemorrhage Related to Vascular Malformation
Vascular malformations can also cause intracranial hemorrhages Fig. 6.9 . Cavernous angioma is a vascular malformation that contains blood cavities sur rounded by a single layer of endothelium 79-83 . MR imaging findings are well known and characterized as a central reticulated core with a peripheral rim of hypointensity due to the deposition of hemosiderin 79,82,83 . DW and b0 images are useful for detecting hemorrhages related to vascular malformations. Multiple cavernous angiomas.The...
DrugInduced Vasculitis Including Illicit Drugs
Some drugs, such as chemotherapeutic agents e.g. sulfonamide, thiouracil and illicit drugs e.g. cocaine , can cause vasculitis 26 . Stroke can occur soon after administration of illicit drugs by an intravenous, oral or nasal route. Cocaine, heroin, amphetamine and other sympathomimetic drugs are most commonly implicated. The diagnosis of vasculitis depends on the pathological findings, not on the an-giographic findings, which are usually non-specific and may simply indicate vasospasm induced by...
Systemic Lupus Erythematosus
Involvement of the CNS occurs in 14-75 of patients with systemic lupus erythematosus SLE 4 . Pathologically, microinfarcts and small vessel vasculopathy are the most common. Vasculopathy affects predominantly the arterioles and capillaries, resulting in vessel tortuosity, vascular hyalinization, endothelial proliferation and perivascular inflammation or gliosis. Spectrum of CNS vasculopathy. Modified from 10 Systemic lupus erythematosus in a 39-year-old woman with recurrent episodes of stroke,...
Brain Stem and Cerebellar Infarcts
Cerebellar infarction is caused by occlusion of one of the major posterior circulation branches, which include the superior cerebellar, the anterior and posterior inferior cerebellar arteries, and the basilar artery. The posterior inferior cerebellar artery PICA supplies the postero-inferior portions of the cerebellum and is the most commonly obstructed cerebellar artery. The size of the infarct is important because a large infarct may cause a significant mass effect on the fourth ventricle and...
A i it
Acute infarction with hyperacute hemorrhage oxy-hemoglobin deoxy-hemoglobin . A 72-year-old woman suffered from a right-sided weakness. MR imaging 30 hours after the onset of symptoms a-c showed a lesion in the right basal ganglia arrow that is hyperintense on DW a and b0 images b .On the ADC map c the lesion is hypointense arrow , indicating that this is a non-hemorrhagic acute infarction. During the end of the MR scanning, 30.5 hours after the onset of symptoms d-f , the patient suddenly lost...
Takayasus Arteritis Aortitis Syndrome
Takayasu's arteritis Fig. 7.5 is a primary arteritis of unknown cause but probably also related to T cellmediated inflammation. Takayasu's arteritis commonly affects large vessels including the aorta and its major branches to the arms and the head. It is more commonly seen in Asia and usually affects young women 19 . Pulseless upper extremities and hypertension are the common clues to suggest the diagnosis. Most patients are treated with steroids alone to reduce the inflammation. The prognosis...
Collagen Vascular Diseases
Beh et's disease is a multisystem vasculitis of unknown origin. It is especially common in Middle Eastern and Mediterranean countries. CNS involvement has been described in 4-49 of cases 6 . The parenchymal distribution of lesions, especially at the mesodiencephalic junction 46 supports small vessel vasculitis involving both the arterial and venous systems mainly venules. The lesions are occasionally reversible on MRI, which mainly represents vasogenic edema, which is why DW imaging is useful...
Early Subacute Hematoma
In the early stage of the subacute hematoma Figs. 6.2 and 6.3 , there is a decline in the energy state of the red blood cell and hemoglobin is oxidized to met-he-moglobin 3,4,7,10,11,14,19,22,23,28-30, 33, 34 . In met-hemoglobin the iron is still bound to the heme moiety within the globin protein, but it is now in the ferric state with five unpaired electrons. This transformation normally starts in the periphery of the hemorrhage and gradually evolves to the center. In the transition to...
Infectious Vasculitis
Infections can cause vasculitis both by direct invasion of the vessel walls and by an immune-mediated response to the pathogens. Bacterial, fungal and some viral vasculitis e.g. herpes virus cause a direct invasion of the vessel walls, usually resulting in infarction Fig. 7.8 2, 24 . Vasculitis with aseptic meningitis is probably related to an immunologic re-action,which can show reversible lesions. Aspergillus infiltrates and destroys the internal elastic lamina of major cerebral arteries,...
Giant Cell Temporal Arteritis
The criteria of the American College of Rheumatology for the diagnosis of giant cell arteritis Fig. 7.4 include at least three of the following 1 age at disease onset gt 50 years, 2 new onset of headache, 3 claudication of jaw or tongue, 4 tenderness of the temporal artery on palpation or decreased pulsation, 5 erythrocyte sedimentation ratio gt 50 mm h and Primary angitis of central nervous system proven by biopsy in a 60-year-old woman with dizziness and speech difficulties. a T2-weighted...
Subarachnoid Hemorrhage
Computed tomography CT is still essential in the diagnosis of acute subarachnoid hemorrhages Fig. 6.5 , as the sensitivity and usefulness of MR imaging is controversial 4,5,9,34,39-45 . Fluid-attenuated inversion-recovery FLAIR imaging has a high sensitivity for subarachnoid hemorrhage 46-49 . However, the specificity is low because there are several other causes for the appearance of subarachnoid hemorrhage on FLAIR imaging, such as high proton concentration, mass effect, vascular disease,...
Characterization of CNS Vasculitis
Vasculitis of the CNS is characterized by the size of the affected vessel, as illustrated in Fig. 7.1 2 . Determining size and location of the predominantly affected vessels is useful to obtain an optimal tissue biopsy and establish appropriate treatment 9 . Large artery vasculitis usually responds well to steroids alone, while small and medium-sized vessel vasculitis respond better to a combination of cytotoxic agents and steroids. Therefore, a clear understanding of the size of the vessels...
Definition
Vasculopathy is a general term used to describe any disease affecting blood vessels 1 . It includes vascular abnormalities caused by degenerative, metabolic and inflammatory conditions, embolic diseases, co-agulative disorders, and functional disorders such as posterior reversible encephalopathy syndrome. The etiology of vasculopathy is generally unknown and the condition is frequently not pathologically proven. Vasculitis, on the other hand, is a more specific term and is defined as...
DiffusionWeighted MR Imaging of the Brain
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Corpus Callosum Infarcts
Isolated corpus callosum infarction due to pericallos-al artery disease is rare, but can present as an alien hand syndrome. These patients fail to recognize the ownership of one hand when placed in certain positions or situations 16 . These lesions are readily detected by DW imaging and have signal characteristics similar to cerebral infarcts Fig. 5.10 . Corpus callosum infarction in a 64-year-old man with left-sided weakness. a T2-weighted image shows a hyperintense lesion in the anterior part...
Vasogenic Edema
Vasogenic edema is characterized by dysfunction of the blood-brain barrier, allowing an abnormal passage of proteins, electrolytes and water into the extracellular compartments. Fluid leaving the capillaries enlarges the extracellular space, predominantly in the white matter. Osmotic and hydrostatic gradients will also cause interstitial edema, increasing the extracellular space as water shifts from blood vessels and or ventricles. Intracellular components are rela tively preserved Fig. 4.14 ,...
Hypoxic Ischemic Encephalopathy
Excitotoxic mechanisms in the neuron and astrocyte. In the neuron, glutamate is released from the pre-synaptic terminal into the synaptic cleft. The glutamate binding to NMDA receptors allows entry of Ca2 into the postsynaptic neuron, which can result in necrotic cell death or apoptosis. The glutamate binding to non-NMDA receptors allows entry of Na into the post-synaptic neuron, resulting in cytotoxic edema of the neuron. Re-uptake of extracellular glutamate takes place at the pre-synaptic...
Shielded Gradients. And The General Solution To The Near Field Problem Of
Normal adult brain of a 40-year-old male without neurological deficits.a Isotropic DW image is obtained by combining b0 image and three orthogonal unidirectional images x,y,z axis .The bilateral globi pallidi have low signal on DW image as a result of physiological iron deposition arrows . Corticospinal tracts have mildly high signal on DW image arrowheads . Gray matter shows mildly high signal compared to white matter.These signal changes on isotropic DW imaging are normal and are caused by T2...
Cytotoxic Edema
An early phase of wallerian degeneration in a 20-year-old woman with subacute infarction 72 h after onset . a T2-weight-ed image shows hyperintense lesion involving the right basal ganglia, the posterior limb of the internal capsule and corona radiata, representing an acute infarct. b T2-weighted image shows hyperintense lesion along the ipsilateral corticospinal tract arrow and substantia nigra arrowheads in the cerebral peduncle, which represents wallerian and transneuronal degeneration...