Tag neuropathalogy [18 articles]

Abstract

Background and Purpose--Cortical reorganization of motor systems has been found in recovered stroke patients. Reorganization in nonrecovered hemiplegic stroke patients early after stroke, however, is less well described. We used positron emission tomography to study the functional reorganization of motor and sensory systems in hemiplegic stroke patients before motor recovery. Methods--Regional cerebral blood flow (rCBF) was measured in 6 hemiplegic stroke patients with a single, subcortical infarct and 3 normal subjects with the [15O]H2O injection technique. Brain activation was achieved ...

Abstract

BACKGROUND AND PURPOSE: Recovery from hemiparesis due to corticospinal tract infarction is well documented, but the mechanism of recovery is unknown. Functional MRI (fMRI) provides a means of identifying focal brain activity related to movement of a paretic hand. Although prior studies have suggested that supplementary motor regions in the ipsilesional and contralesional hemisphere play a role in recovery, little is known about the time course of cortical activation in these regions as recovery proceeds. METHODS: Eight patients with first-ever corticospinal ...

Abstract

BACKGROUND AND PURPOSE: The aim of the present study was to examine movement-related potentials (MRPs) in patients in the "chronic" stage after cortical stroke with recovered hemiparesis compared with healthy control subjects. METHODS: Right index finger MRPs were derived from 12 patients > or =1 year after infarction in the territory of the left middle cerebral artery as well as from 12 control subjects. MRP components were compared between groups. RESULTS: In the patient group, the component directly preceding movement onset ...

Abstract

1. Intracortical microstimulation (ICMS) techniques were used to derive detailed maps of distal forelimb movement representations in primary motor cortex (area 4) of adult squirrel monkeys before and a few months after a focal ischemic infarct. 2. Infarcts caused a marked but transient deficit in use of the contralateral hand, as evidenced by increased use of the ipsilateral hand, and reduced performance on a task requiring skilled digit use. 3. Infarcts resulted in a widespread reduction in the areal extent of ...

Abstract

Programmed cell death (PCD) is involved in the removal of superfluous and damaged cells in most organ systems. The induction phase of PCD or apoptosis is characterized by an extreme heterogeneity of potential PCD-triggering signal transduction pathways. During the subsequent effector phase, the numerous PCD-inducing stimuli converge into a few stereotypical pathways and cells pass a point of no return, thus becoming irreversibly committed to death. It is only during the successive degradation phase that vital structures and functions are destroyed, ...

Abstract

Although free radicals have been suggested to contribute to ischemic brain damage for more than 10 years, it is not until quite recently that convincing evidence has been presented for their involvement in both sustained and transient ischemia. The hypothesis is examined against current knowledge of free radical chemistry, as it applies to biological systems, and of cellular iron metabolism. It is emphasized that those advents have changed our outlook on free radical-induced tissue damage. First, it has been realized that ...

Abstract

Background Stroke is the third leading cause of death and the leading cause of long-term disability in the United States. Although a host of genetic, biochemical, physiological, anatomic, and histological factors have been implicated, to varying degrees, in the pathogenesis of stroke, biophysical factors are believed to play a significant role in the development, diagnosis, and therapy of stroke. The purpose of this review article is to identify, describe, and illustrate these causes and biophysical and hemodynamic mechanisms predisposing a person ...

Abstract

The aim of this study was to evaluate the relationships of morphological and CBF patterns with both the severity and the evolution of the motor deficit in the late phase of stroke and, in particular, to identify morphological and/or functional brain alterations associated with a persistent severe motor deficit or a poor, delayed motor recovery. We analysed CT/MRI and single photon emission tomography (SPET) findings from 37 patients studied in the chronic phase of stroke (mean duration +/- SD = 3.6 ...

Abstract

Fifteen patients with acute cerebral hemispheric infarcts have been studied with positron emission tomography and the oxygen-15 steady-state inhalation technique. Thirteen follow-up studies were also performed. The values of cerebral oxygen metabolism (CMRO2), cerebral blood flow (CBF), and oxygen extraction ration (OER) have been calculated for the infarcted regions, their borders, the symmetrical regions in contralateral cerebral hemispheres, and the cerebellar hemispheres. This study demonstrates that in the completed stroke there are thresholds for regional CMRO2 and regional CBF below which ...