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At least 937 records · Page 52Linked to original sources
PubMed2002

Functional magnetic resonance neuroimaging of drug dependence: naloxone-precipitated morphine withdrawal.

This study investigated the potential utility of fMRI as a neuroimaging technique to examine drug dependence using a robust animal model of drug withdrawal. Two groups of rats chronically pretreated with incremental doses of morphine sulfate (2, 7, 15, 30, 40, 50, 50, and 50 mg/kg--subcutaneous injection) were subjected to opioid precipitated withdrawal (using the opioid antagonist, naloxone) and subsequently behaviorally assessed or gradient-echo imaged under urethane anesthesia. Whole brain, group statistical parametric maps revealed statistically significant changes in signal intensity following administration of 1 mg/kg naloxone (corrected for multiple comparisons: P < 0.05, T > 5.03). Control groups within the fully crossed designs did not exhibit any statistically significant changes in behavior or signal intensity changes. Regional patterns of modulated activity include the retrosplenial, piriform, insular, entorhinal, cingulate, visual and auditory cortices, posterior fields of the hippocampus, and in particular the dentate gyrus. Such areas are consistent with biochemical correlates of morphine withdrawal and time profiles derived from our behavioral observations (P < 0.02). A notable lack of signal intensity changes in a number of subcortical areas suggests a possible confound associated with fMRI under anesthesia. This paper reports the first whole brain fMRI examination of an animal model of drug withdrawal, we believe there is considerable scope for extrapolation of our methods to a multitude of pharmacological applications-most notably in conjunction with other techniques in the development of potential therapeutic agents for drug dependence.

Animals↗
PubMedDate not supplied

[Functional neuroimaging of auditory hallucinations in schizophrenia].

The neurobiological bases underlying the generation of auditory hallucinations, a distressing and paradigmatic symptom of schizophrenia, are still unknown in spite of in-depth phenomenological descriptions. This work aims to make a critical review of the latest published literature in recent years, focusing on functional neuroimaging studies (PET, SPECT, fMRI) of auditory hallucinations. Thus, the studies are classified according to whether they are sensory activation, trait and state. The two main hypotheses proposed to explain the phenomenon, external speech vs. subvocal or inner speech, are also explained. Finally, the latest unitary theory as well as the limitations the studies published are commented on. The need to continue investigating in this field, that is still underdeveloped, is posed in order to understand better the etiopathogenesis of auditory hallucinations in schizophrenia.

Brain↗
PubMedDate not supplied

[Lumbar puncture and early neuroimaging in complex febrile seizures. Report of a case of shaken infant syndrome].

INTRODUCTION: Febrile convulsions are one of the most frequent pathologies seen in paediatric emergencies. The diagnosis of febrile seizures is clinico evolutionary and is easily established once the acute process is overcome and a normal state is restored in the child. The differential diagnosis is established with the processes that associate fever and convulsions in children between the ages of 1 month and 6 years, many of which require specific treatment. Certain complementary examinations, essentially a blood test, lumbar puncture and neuroimaging, are needed to identify them. Shaken infant syndrome is a form of physical abuse which includes the presence of intracranial traumatic injury, retinal haemorrhage and, in general, the absence of other physical signs of traumatic injury in the child. CASE REPORT: An 8 month old infant who presented a convulsive seizure on the left side of the body which coincided with an axillary temperature of 38 C that remitted with intravenous diazepam 40 minutes after onset. An early cranial computerised tomography (CT) scan led to a diagnosis of shaken infant syndrome. DISCUSSION: This case constitutes an argument in favour of performing an early cranial CT scan in complex febrile convulsions and in prolonged or partial non provoked seizures. We highlight the risks involved in performing a lumbar puncture in the absence of suspected non complicated acute bacterial meningitis. The diagnostic usefulness of an early CT scan in diagnosing such an important problem as shaken infant syndrome must also be noted, due to the risk of repetition and its high morbidity and mortality rates.

Brain↗
PubMed2003

Functional neuroimaging (PET and SPECT) in the selection and assessment of patients with Parkinson's disease undergoing deep brain stimulation.

Deep brain Stimulation (DBS) is an effective treatment for patients with advanced Parkinson's disease (PD) and motor complications who can no longer be improved by adjustment of medical therapy. Selection of surgery candidates and follow-up after surgery are critical for good outcome. Functional neuroimaging can help in the clinical assessment of these patients. We have used single photon emission computed tomography (SPECT) and the tracer ECD to measure regional cerebral blood flow before and 6 months after DBS of the subthalamic nucleus (STN) in 20 patients with advanced PD. We found a significant increase in the anterior cingulate/supplementary motor cortex in the 12 good responders (change in off unified UPDRS >50%). Conversely, patients with poor response (n=8; change in off UPDRS-III <50% following DBS) revealed a significant worsening of cortical hypoperfusion particularly in the prefrontal areas. No flow decrements were detected in the basal ganglia and in the thalamus in both groups during DBS stimulation suggesting that DBS does not have a "lesion like" effect. If DBS stimulates and does not inactivate STN projection neurons, flow reduction in the poor responders may be secondary to increased inhibitory basal ganglia output.

Cerebrovascular Circulation↗
PubMed1992

[Neurological and neuroimaging studies of eclampsia].

Clinical and neuroimaging studies were made in twenty-one patients during the attack of eclampsia. Most frequent neurological signs and symptoms were the impairment of consciousness, headache, seizure and visual disturbance. Mean arterial blood pressure increased by 46 mmHg (n = 21) during the attacks. Eight of 9 patients studied by CT and/or MRI showed transient abnormalities on brain images during the attack in the occipital cortex, basal ganglia, and internal and external capsule. The findings were compatible with brain edema and were seen mainly in the white matter. Cerebral blood flow measured by SPECT method in one patient during an attack with visual disturbance showed increased blood flow in the occipital cortex. Acute increase in blood pressure, cerebral hyperperfusion and edema, similar to the pathophysiology of hypertensive encephalopathy, were considered to play an important role in the pathogenesis of eclampsia.

Adult↗
PubMed2003

Uptake-1 carrier downregulates in parallel with the beta-adrenergic receptor desensitization in rat hearts chronically exposed to high levels of circulating norepinephrine: implications for cardiac neuroimaging in human cardiomyopathies.

UNLABELLED: Imaging techniques have demonstrated in various cardiomyopathies that an altered uptake of radiolabeled norepinephrine (NE) analogs may coexist with beta-adrenergic receptor downregulation, but the relationships between these 2 alterations and their mechanisms remain unclear. The aim of this study was to evaluate the hypothesis of a chronic elevation of circulating NE levels as a mechanism of decreased uptake of radiolabeled NE analogs and reduced beta-adrenergic receptor sites in the heart. METHODS: Osmotic minipumps containing either NE or NaCl were implanted intravenously in rats for 5 d. The uptake-1 function was assessed in vitro by measuring in excised hearts (3)H-NE and (123)I-metaiodobenzylguanidine ((123)I-MIBG) uptakes and uptake-1 carrier density using (3)H-mazindol binding assay. The myocardial beta-adrenergic receptor pathway was assessed in vitro by (3)H-CGP 12177 binding and measurement of adenylyl cyclase activity at baseline and under stimulation. RESULTS: A 34% decrease in (3)H-NE uptake and a 35% decrease in (123)I-MIBG uptake were found in the hearts of rats infused with the NE pump compared with that of rats infused with saline solution (P < 0.05 for both). Moreover, the uptake-1 carrier protein density was decreased by 29% (P < 0.05) and 33% (P < 0.05) in right and left ventricles, respectively, of rats infused with NE compared with those infused with saline solution. Myocardial beta-adrenergic receptor desensitization was associated with a 36% reduction in receptor density in the right ventricle (P < 0.05) and a 31% reduction in the left ventricle (P < 0.05) of rats infused with NE compared with those infused with saline solution. CONCLUSION: The decrease in myocardial beta-adrenergic receptors and radiolabeled NE analog uptake found in different cardiomyopathies using neuroimaging techniques may be related to a functional mechanism of NE-induced downregulation of both beta-adrenergic receptor and uptake-1 carrier sites.

3-Iodobenzylguanidine↗
PubMed2003

[Neuroimaging in a chronic demyelination process following tick-borne encephalomyelitis].

We present a case of a 17-year-old female patient with a tick-borne neuroinfection. Tick-borne encephalitis is a viral disease of the CNS. Tick-borne encephalitis is usually of diphasic type, with partial epileptic seizures. No such symptoms were observed in this case. Since areas of demyelination could be seen on CT and MRI scans, immunological etiology should be taken into consideration. The correct diagnosis was established on the basis of serological examination and neuroimaging findings.

Adolescent↗
PubMed2003

Neuroimaging of focal cortical dysplasia: neuropathological correlations.

Focal cortical dysplasia is a well-known cause of intractable epilepsy with early onset of seizures, and is potentially amenable to surgical therapy. It was first described by Taylor in 1971 as a peculiar malformative disorganisation of the neocortex characterised at histology by loss of cortical lamination and accompanied by giant, dysmorphic neurones and, most frequently, by "balloon cells" littered throughout the cortex and sub-cortical white matter. While in the past decades the term "cortical dysplasia" has referred to various malformations of cortical development, such as agyria, pachygyria, polymicrogyria, heterotopia and hemimegalencephaly, it is now widely accepted that the entity identified by Taylor should be considered separately, from both histological and neuroimaging standpoints. More recently, the recognition of various histological subtypes of focal cortical dysplasia characterised by different degrees of cortical disruption with or without cytological abnormalities has generated several classifications that are still unsatisfactory. With better magnetic resonance capability, subtle and very small focal cortical dysplasias may now be visualised and the differential magnetic resonance aspects of the histological subgroups can be established. We will discuss the problem of histopathological classification and magnetic resonance imaging differentiation of the various subtypes of focal cortical dysplasia in the light of personal data collected from a large series of epileptic patients who underwent surgery and had a histological diagnosis of focal cortical dysplasia.

Atrophy↗
PubMed2003

Functional neuroimaging of malformations of cortical development.

Functional neuroimaging over the past 10 years has led to greater insights into the pathophysiology underlying symptomatic epilepsy. Such imaging has been used to localize cerebral dysfunction, predominantly through disturbances in metabolism or blood flow. Techniques available include single photon emission computed tomography (SPECT), positron emission tomography (PET) and functional magnetic resonance imaging (fMRI). Although the use of these diagnostic techniques is widely reported for presurgical evaluation, there has been little work with specific reference to malformations of cortical development.

Adolescent↗
PubMed1992

Neuroimaging studies of obsessive compulsive disorder.

In the last 5 years, there has been an explosion of neuroimaging studies of obsessive compulsive disorder. This work is now beginning to suggest dysfunctional brain regions and circuits that may mediate some of the symptoms of this classic neuropsychiatric illness.

Blood Glucose↗
PubMed2003

Memory processing during human sleep as assessed by functional neuroimaging.

Sleep is believed to participate in memory consolidation, possibly through off-line processing of recent memory traces. In this paper, we summarize functional neuroimaging data testing this hypothesis. First, sleep deprivation disrupts the processing of recent memory traces and hampers the changes in functional segregation and connectivity which underpin the gain in performance usually observed in subjects allowed to sleep on the first post-training night. Second, experience-dependent changes in regional brain activity occur during post-training sleep. These changes are shown to be related to the processing of high-level material and to be modulated by the amount of learning achieved during the training session. These changes do not involve isolated brain areas but entire macroscopic cerebral networks. These data suggest a role for sleep in the processing of recent memory traces.

Adult↗
PubMed2003

Cerebrotendinous xanthomatosis: neuroimaging findings in two siblings from an Indian family.

Cerebrotendinous xanthomatosis (CTX) is exceptionally rare in the Indian population. We present and discuss the clinical, radiological and histopathologic findings in 2 siblings with CTX. Both the patients had juvenile cataract, mental retardation and marked cerebellar ataxia. The Achilles tendon swelling was present in only 1 patient (Case 2). MR imaging showed typical bilateral and symmetrical involvement of the dentate nuclei, inferior olives, brainstem and cerebellar hemispheric white matter. Although the diagnosis of CTX was made in the 3rd decade in both our cases, early diagnosis is possible if neuroimaging is done in the early course of the disease.

Adult↗
PubMed2003

Functional neuroimaging of auditory processing.

There is a complex functional organization of the central auditory system from the brainstem to primary and associative auditory cortices. Functional neuroimaging has been used to visualize and confirm the spatial distribution of brain activation in temporal areas for the processing of simple acoustic stimuli. Brain activity is much more complex for words, and different networks can be recruited when phonological, lexical and semantic levels of processing are engaged.

Auditory Cortex↗
PubMedDate not supplied

[Clinical and neuroimaging findings in a family with CADASIL associated to C475T mutation].

INTRODUCTION: The term CADASIL (cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy) refers to an autosomal dominant hereditary arteriopathy of the brain that is characterised by headache, recurring strokes and progressive cognitive deterioration. We report the case of another family with CADASIL and emphasise the importance of a genetic study in its diagnosis. CASE REPORT: A 62-year-old female patient with repeating lacunar strokes, subcortical dementia and a family history of dementia and strokes. Neuroimaging studies conducted on the patient and her siblings showed signs of leukoencephalopathy and lacunar infarctions. The ultrastructural study of the biopsy performed on a sample of the patient's skin, which included five dermal vessels, did not show any electron-dense deposits. The genetic study revealed the presence of mutation C475T in exon 4 of NOTCH3. CONCLUSIONS: The possible presence of CADASIL must be suspected in patients with symptoms of cerebrovascular disease or dementia who present characteristic alterations in the magnetic resonance brain scan, especially when there is a compatible family history. The first choice diagnostic procedure must be a genetic study.

Dementia, Multi-Infarct↗
PubMed2004

[Diagnostic yield in studies of autism. The contribution made by neuroimaging, metabolic tests and genetic studies].

AIMS: We reviewed the literature on the diagnostic yield of the different medical tests carried out on autistic patients in order to determine the aetiology of the process. DEVELOPMENT: Although it is generally said that a causation of the process can be determined in 10 30% of cases, the actual diagnostic yield of autism when a routine diagnosis is applied is between 2 and 7%. The diagnostic yield of radiology, metabolic studies and genetic studies was analysed. Genetic tests are the ones that offer the highest efficiency, and carrying out a karyotype and molecular study of fragile X chromosome syndrome is indicated in all patients with mental retardation associated to autism. The next most efficient are metabolic studies, which become particularly important mainly in populations where no screening has previously been conducted for metabolic disorders. CONCLUSIONS: Despite their being capable of showing up a large number of disorders, neuroimaging studies are unspecific and the diagnostic yield of radiological studies is very low when they are conducted on a routine basis.

Autistic Disorder↗
PubMed2004

Neurobrucellosis: clinical and neuroimaging correlation.

BACKGROUND AND PURPOSE: Manifestation of nervous system involvement by neurobrucellosis, a treatable infection, is not well documented. We investigated patterns of nervous system involvement and determined if neuroimaging abnormalities correlated with clinical manifestations of neurobrucellosis. METHODS: We reviewed 23 MR imaging studies (17 of brain, six of spine) and seven CT scans of brain in 23 patients (14 male and nine female patients; age range 17-71 years) with positive Brucella titers in their serum and CSF. RESULTS: Twelve patients had central nervous system (CNS) involvement, four had peripheral nervous system (PNS) involvement, two had combined PNS and CNS involvement, and five had isolated hearing loss. Imaging findings were variable: five of seven brain CT studies were normal, and 10 of 23 MR studies were normal (eight brain, one thoracic, one lumbar). One brain CT study showed subthalamic hemorrhage, mild perivascular enhancement, left caudate lacunae, and diffuse white matter changes. One other brain CT study showed enhancement of the tentorium in addition to white matter changes. Abnormal MR findings were basal meningeal enhancement (n = 3), lumbar nerve root enhancement (n = 3), granuloma of the suprasellar region (n = 1), diffuse white matter changes (n = 7), and spinal cord atrophy (n = 1). All patients improved after treatment with three antimicrobial drugs for 3-12 months. Seven patients had follow-up imaging; the enhancement disappeared but the white matter and ischemic changes persisted despite almost complete clinical recovery. CONCLUSION: Clinical-radiologic correlation in neurobrucellosis varies from a normal imaging study despite positive clinical findings, to a variety of imaging abnormalities that reflect either an inflammatory process, an immune-mediated process, or a vascular insult.

Adolescent↗
PubMed2004

Neuroimaging in posterior reversible encephalopathy syndrome.

The terms posterior reversible leukoencephalopathy, reversible posterior cerebral edema syndrome, and posterior reversible encephalopathy syndrome (PRES) all refer to a clinicoradiologic entity characterized by headaches, confusion, visual disturbances, seizures, and posterior transient changes on neuroimaging. Clinical findings are not sufficiently specific to readily establish the diagnosis; in contrast, magnetic resonance imaging pattern is often characteristic and represents an essential component of the diagnosis of PRES. Typical lesions predominate in the posterior white matter, with some involvement of the overlying cortex; are hyperintense on T2-weighted images; and are usually hypointense or isointense on diffusion-weighted images, with an increase of the apparent diffusion coefficient, indicating vasogenic edema. The pathogenesis is incompletely understood, although it seems to be related to the breakthrough of autoregulation and endothelial dysfunction. Since its initial description, this syndrome has been subsequently described in an increasing number of medical conditions, including hypertensive encephalopathy, eclampsia, and the use of cytotoxic and immunosuppressive drugs. The diagnosis has important therapeutic and prognostic implications because the reversibility of the clinical and radiologic abnormalities is contingent on the prompt control of blood pressure and/or discontinuing the offending drug. On the contrary, when unrecognized, conversion to irreversible cytotoxic edema may occur.

Brain↗
PubMed2004

[Three-dimensional neuroimaging in diagnosis and surgical treatment for epilepsy].

Development of functional neuroimaging is contributed to diagnosis and treatment in epilepsy patients. The dipole analysis of interictal spikes on EEG or MEG provides 3D-localization of the irritable zone. Interictal and ictal CBF-SPECT reveals the local change in CBF associated to epileptic focus. Three-dimensional stereotactic surface projection (3D-SSP) of SPECT is useful to recognize the seizure generation area. Furthermore, Subtraction ictal SPECT coregistration of MRI (SISCOM), that is fusion image of anatomical and functional brain images, is beneficial to understand the localization of seizure-induced hyperperfusion area. During epilepsy surgery, image-guided system makes less-invasive and accurate surgery possible. Functional image-guided surgery for epilepsy will be available in near future.

Adult↗