RESUMO
Most dementias begin insidiously, developing slowly and generally occurring in the elderly age group. The so-called rapidly progressive dementias constitute a different, diverse collection of conditions, many of which are reversible or treatable. For this reason, accurate identification and assessment of acute and subacute forms of dementia are critical to effective treatment; neuroimaging aids greatly in narrowing the diagnosis of these conditions. This second installment of a 2-part review of rapidly progressive dementias examines the use of imaging in an assortment of other etiologies in the differential diagnosis, from prion disease and neoplastic-related conditions to rare metabolic and other conditions such as Wernicke encephalopathy. In these clinical conditions, MR imaging has the potential to narrow this broad differential diagnosis and, at times, can definitively aid in the diagnosis of certain conditions on the basis of typical imaging patterns.
Assuntos
Demência/diagnóstico , Neuroimagem , Neoplasias Encefálicas/complicações , Demência/etiologia , Diagnóstico Diferencial , Progressão da Doença , Encefalite/complicações , Humanos , Síndromes Paraneoplásicas/complicações , Doenças Priônicas/complicações , Fatores de TempoRESUMO
Most dementias begin insidiously, developing slowly and generally occurring in the elderly age group. The so-called rapidly progressive dementias constitute a different, diverse collection of conditions, many of which are reversible or treatable. For this reason, prompt identification and assessment of acute and subacute forms of dementia are critical to effective treatment. Numerous other entities within this category of presenile rapid-onset dementias are untreatable such as the prion-related diseases. Neuroimaging aids in the diagnosis and evaluation of many of these rapidly progressive dementias, which include myriad conditions ranging from variations of more common neurodegenerative dementias, such as Alzheimer disease, dementia with Lewy bodies, and frontotemporal dementia; infectious-related dementias such as acquired immune deficiency syndrome dementia; autoimmune and malignancy-related conditions; to toxic and metabolic forms of encephalopathy. This first of a 2-part review will specifically address the ability of MR imaging and ancillary neuroimaging strategies to support the diagnostic evaluation of rapidly progressive dementias due to neurodegenerative causes.
Assuntos
Demência/diagnóstico , Neuroimagem , Demência/etiologia , Progressão da Doença , Humanos , Doenças Neurodegenerativas/complicações , Fatores de TempoRESUMO
SUMMARY: Advances in nanotechnology have the potential to dramatically enhance the detection of neurologic diseases with targeted contrast agents and to facilitate the delivery of focused therapies to the central nervous system. We present the physicochemical rationale for their use, applications in animal models, and ongoing clinical trials using these approaches. We highlight advances in the use of nanoparticles applied to brain tumor imaging, tumor angiogenesis, neurodegeneration, grafted stem cells, and neuroprogenitor cells.
Assuntos
Encefalopatias/diagnóstico , Encéfalo/metabolismo , Imagem Molecular/tendências , Nanopartículas , Nanotecnologia/tendências , Neuroimagem/tendências , Animais , Encéfalo/patologia , Meios de Contraste , HumanosRESUMO
Alzheimer disease prevails as a major cause of disability in the elderly population and ranks as the most common form of dementia that affects 1 of 8 individuals older than 65 years of age. Most AD cases are late in onset and are probably influenced by both genetic and environmental factors. Apart from age, the risk factors include family history; brain injury, both traumatic and vascular; and metabolic diseases, such as diabetes, hypercholesterolemia, and obesity. Based on twin studies, inheritance plays a role in approximately 80% of cases (familial and sporadic).
Assuntos
Doença de Alzheimer/genética , Doença de Alzheimer/diagnóstico , HumanosAssuntos
Encéfalo/patologia , Diagnóstico por Imagem/métodos , Predisposição Genética para Doença/genética , Doença de Huntington/diagnóstico , Doença de Huntington/genética , Proteínas do Tecido Nervoso/genética , Encéfalo/diagnóstico por imagem , Humanos , Proteína Huntingtina , Polimorfismo de Nucleotídeo Único/genética , RadiografiaAssuntos
Síndrome de Creutzfeldt-Jakob/classificação , Síndrome de Creutzfeldt-Jakob/genética , Marcadores Genéticos/genética , Predisposição Genética para Doença/epidemiologia , Predisposição Genética para Doença/genética , Polimorfismo de Nucleotídeo Único/genética , Príons/genética , Síndrome de Creutzfeldt-Jakob/epidemiologia , Humanos , Prevalência , Proteínas PriônicasRESUMO
Neurofibromatosis types 1 and 2 are a group of neurocutaneous syndromes resulting from disorders in cell regulation. Despite sharing a common name, neurofibromatosis types 1 and 2 are quite distinct phakomatoses, both clinically and genetically.
Assuntos
Aumento da Imagem/métodos , Imageamento por Ressonância Magnética/métodos , Neurofibromatose 1/diagnóstico , Neurofibromatose 2/diagnóstico , Predisposição Genética para Doença/genética , Humanos , Neurofibromatose 1/genética , Neurofibromatose 2/genéticaRESUMO
As experts in the realm of applying brain imaging technology for meaningful information on an individual patient's medical care, neuroradiologists can provide a physiologic, pathophysiologic, and clinical context for the advances achieved from brain-mapping. Precise identification of the abnormalities involved in brain conditions resulting from a multidisciplinary effort including neuroradiology will help to further define the nature of the pathology, evaluate the results of therapy, and improve health care.
Assuntos
Encefalopatias/diagnóstico , Encefalopatias/fisiopatologia , Mapeamento Encefálico/métodos , Encéfalo/anatomia & histologia , Encéfalo/fisiologia , Conectoma/métodos , Neurorradiografia/métodos , HumanosRESUMO
Papilledema, defined as swelling of the optic disc, frequently occurs in the setting of increased ICP and in a variety of medical conditions, including pseudotumor cerebri, sinus thrombosis, intracerebral hemorrhage, frontal lobe neoplasms, and Chiari malformation. Noninvasive imaging of the ON is possible by using MR imaging, with a variety of findings occurring in the setting of papilledema, including flattening of the posterior sclera, protrusion of the optic disc, widening of the ONS, and tortuosity of the ON. Early recognition of papilledema and elevated ICP is of paramount importance for ensuring restoration of vision. Newer advanced MR imaging techniques such as fMRI and DTI may prove useful in the future to assess the potential effects of papilledema on retinal and visual pathway integrity.
Assuntos
Hipertensão Intracraniana/complicações , Hipertensão Intracraniana/patologia , Imageamento por Ressonância Magnética/métodos , Disco Óptico/patologia , Papiledema/complicações , Papiledema/patologia , Vias Visuais/patologia , HumanosRESUMO
SUMMARY: GABA serves as a major neurotransmitter of the brain and functions mainly to inhibit neural excitatory activity. Disruption of the GABAergic processes appears to occur in various neurologic and psychiatric conditions, including epilepsy, mood disorders, motor disorders such as focal dystonia and stiff-person syndrome, sleep disorders, neuroplasticity, and drug and alcohol dependence. These concentration differences may be ascertained by using MR spectroscopy to provide information on the concentration of different metabolites. This review briefly discusses advances in MR spectroscopy methods and explores the application of this technique to detect changes in GABA due to disease processes and medication-induced effects.
Assuntos
Encefalopatias/metabolismo , Encefalopatias/fisiopatologia , Espectroscopia de Ressonância Magnética/métodos , Inibição Neural/fisiologia , Ácido gama-Aminobutírico/fisiologia , Antipsicóticos/uso terapêutico , Encefalopatias/tratamento farmacológico , Antagonistas GABAérgicos/uso terapêutico , HumanosRESUMO
PTC is a clinical entity of uncertain etiology characterized by intracranial hypertension. The syndrome classically manifests with headaches and visual changes in women with obesity. Traditionally, imaging ruled out secondary causes of elevated CSF pressure but now may reveal findings frequently seen in patients with PTC, including the following: flattening of the globe, an empty sella, an enlarged ONS, protrusion and enhancement of the optic nerve head, and increased tortuosity of the optic nerve. Novel imaging methods, including MR venography, have additionally identified sinovenous stenosis as a potential indicator of PTC.
Assuntos
Encéfalo/patologia , Hipertensão Intracraniana/diagnóstico , Imageamento por Ressonância Magnética/métodos , Pseudotumor Cerebral/diagnóstico , Transtornos da Visão/patologia , Feminino , Humanos , Hipertensão Intracraniana/etiologia , Obesidade/complicações , Pseudotumor Cerebral/etiologia , SíndromeAssuntos
Barreira Hematoencefálica/metabolismo , Meios de Contraste/farmacocinética , Gadolínio/farmacocinética , Imageamento por Ressonância Magnética , Animais , Encefalopatias/metabolismo , Líquido Cefalorraquidiano/metabolismo , Humanos , Insuficiência Renal/metabolismo , Espaço Subaracnóideo/metabolismoRESUMO
PURPOSE: Our goal was to use functional MRI (fMRI) of brain to reveal activation in each cerebral hemisphere in response to imagination and smell of odors. METHOD: FMRI brain scans were obtained in 24 normal subjects using multislice fast low angle shot (FLASH) MRI in response to imagination of banana and peppermint odors and in response to smell of corresponding odors of amyl acetate and menthone, respectively, and of pyridine. Three coronal sections selected from anterior to posterior brain regions were used. Similar studies were obtained in two patients with hyposmia using FLASH MRI and in one patient with hyposmia using echo planar imaging (EPI) both before and after theophylline treatment that returned smell function to or toward normal in each patient and in two patients with birhinal phantosmia (persistent foul odor) and global phantogeusia (persistent foul taste) with FLASH and EPI fMRI before and after treatment with neuroleptic drugs that inhibited their phantosmia and phantogeusia. Activation images were derived using correlation analysis. Ratios of hemispheric areas of brain activation to total hemispheric brain areas were calculated for FLASH fMRI, and numerical counts of pixel clusters in each hemisphere were made for EPI studies. Total pixel cluster counts in localized regions of each hemispheric section were also obtained. RESULTS: In normal subjects, activation generally occurred in left (L) > right (R) brain hemisphere in response to banana and peppermint odor imagination and to smell of corresponding odors of amyl acetate and menthone. Whereas there were no overall hemispheric differences for pyridine odor, activation in men was R > L hemisphere. Although absolute activation in both L and R hemispheres in response to banana odor imagination and amyl acetate smell was men > women, the ratio of L to R activation was women > men. In hyposmic patients studied by FLASH fMRI, activation to banana odor imagination and amyl acetate smell was L > R hemisphere both before and after theophylline treatment. In the hyposmic patient studied with EPI before theophylline treatment, activation to banana and peppermint odor imagination and to amyl acetate, menthone, and pyridine smell was R > L hemisphere; after theophylline treatment restored normal smell function, activation shifted completely with banana and peppermint odor imagination and amyl acetate and menthone smell to L > R hemisphere, consistent with responses in normal subjects. However, this shift also occurred for pyridine smell, which is opposite to responses in normal control subjects. In patients with phantosmia and phantogeusia, activation to phantosmia and phantogeusia before treatment was R > L hemisphere; after treatment inhibited phantosmia and phantogeusia, activation shifted with a slight L > R hemispheric lateralization. Localization of all lateralized responses indicated that anterior frontal and temporal cortices were brain regions most involved with imagination and smell of odors and with phantosmia and phantogeusia presence. CONCLUSION: Imagination and smell of odors perceived as pleasant generally activated the dominant or L > R brain hemisphere. Smell of odors perceived as unpleasant and unpleasant phantosmia and phantogeusia generally activated the contralateral or R > L brain hemisphere. With remission of phantosmia and phantogeusia, hemispheric activation was not only inhibited, but also there was a slight shift to L > R hemispheric predominance. Predominant L > R hemispheric differences in brain activation in normal subjects occurred in the order amyl acetate > menthone > pyridine, consistent with the hypothesis that pleasant odors are more appreciated in L hemisphere and unpleasant odors more in R hemisphere. Anterior frontal and temporal cortex regions previously found activated by imagination and smell of odors and phantosmia and phantogeusia perception accounted for most hemispheric differences.
Assuntos
Encéfalo/fisiologia , Imaginação , Odorantes , Olfato/fisiologia , Adulto , Feminino , Lateralidade Funcional , Humanos , Imageamento por Ressonância Magnética , Masculino , Fatores SexuaisRESUMO
In a screening for antifungal metabolites, two indole compounds of mixed biogenesis, 1H-indole-3-carboxylic acid, 1-(1,1-dimethyl-2-propenyl) methyl ester and 1H-indole-3-carboxylic acid, 1-(2,3-dihydroxy-1,1-dimethylpropyl) methyl ester were isolated from a culture of the basidiomycete Aporpiums caryae. The structural elucidation of these compounds was accomplished by spectroscopic methods.