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PubMedDate not supplied

[Antiphospholipid antibody syndrome as a possible cause of paresis in a child].

The Authors report on the case of a 4-year-old boy, admitted to the pediatric department for left hemiplegia. CT scan of the brain was negative on the day of admission but, on the following day, showed 3 small hypodense focal lesions in the posterior branch of the internal capsule, in the knee of the internal capsule and in the posterior parietal region of the cortex. The acute phase almost completely resolved in 10 days. Twenty days after presentation, cerebral angiography showed a thrombosis of an anterior, right perforating vessel, together with the hypoplasia of the horizontal portion of the cerebral anterior artery. The determination of anti-cardiolipin antibodies, even though performed far from the acute phase of the disease, showed a low IgG positivity. Two months after the onset the neurological symptoms completely resolved. In the presence of hypoplasia, narrowing and other lesions of cerebral vessel, it is possible to hypotesize that the occurrence of thrombotic fenomen, ascribable to anti-phaspholipid antibodies, is responsible for the neurological symptoms. The association of thrombosis and anti-phospholipid antibodies suggest that the assessment of anti-phospholipid antibodies should be routinely performed in the presence of thrombotic phenomena.

Antibodies, Antiphospholipid↗
PubMed2006

Diffusion tensor imaging of frontal lobe white matter tracts in schizophrenia.

We acquired diffusion tensor and structural MRI images on 103 patients with schizophrenia and 41 age-matched normal controls. The vector data was used to trace tracts from a region of interest in the anterior limb of the internal capsule to the prefrontal cortex. Patients with schizophrenia had tract paths that were significantly shorter in length from the center of internal capsule to prefrontal white matter. These tracts, the anterior thalamic radiations, are important in frontal-striatal-thalamic pathways. These results are consistent with findings of smaller size of the anterior limb of the internal capsule in patients with schizophrenia, diffusion tensor anisotropy decreases in frontal white matter in schizophrenia and hypothesized disruption of the frontal-striatal-thalamic pathway system.

Journal Article↗
PubMed2005

DTI and MTR abnormalities in schizophrenia: analysis of white matter integrity.

Diffusion tensor imaging (DTI) studies in schizophrenia demonstrate lower anisotropic diffusion within white matter due either to loss of coherence of white matter fiber tracts, to changes in the number and/or density of interconnecting fiber tracts, or to changes in myelination, although methodology as well as localization of such changes differ between studies. The aim of this study is to localize and to specify further DTI abnormalities in schizophrenia by combining DTI with magnetization transfer imaging (MTI), a technique sensitive to myelin and axonal alterations in order to increase specificity of DTI findings. 21 chronic schizophrenics and 26 controls were scanned using Line-Scan-Diffusion-Imaging and T1-weighted techniques with and without a saturation pulse (MT). Diffusion information was used to normalize co-registered maps of fractional anisotropy (FA) and magnetization transfer ratio (MTR) to a study-specific template, using the multi-channel daemon algorithm, designed specifically to deal with multidirectional tensor information. Diffusion anisotropy was decreased in schizophrenia in the following brain regions: the fornix, the corpus callosum, bilaterally in the cingulum bundle, bilaterally in the superior occipito-frontal fasciculus, bilaterally in the internal capsule, in the right inferior occipito-frontal fasciculus and the left arcuate fasciculus. MTR maps demonstrated changes in the corpus callosum, fornix, right internal capsule, and the superior occipito-frontal fasciculus bilaterally; however, no changes were noted in the anterior cingulum bundle, the left internal capsule, the arcuate fasciculus, or inferior occipito-frontal fasciculus. In addition, the right posterior cingulum bundle showed MTR but not FA changes in schizophrenia. These findings suggest that, while some of the diffusion abnormalities in schizophrenia are likely due to abnormal coherence, or organization of the fiber tracts, some of these abnormalities may, in fact, be attributed to or coincide with myelin/axonal disruption.

Adolescent↗
PubMed1992

Subcortical topography and proportions of the pyramidal tract.

The pyramidal tract (PT) was dissected in 30 normal human hemispheres according to the method of Klingler. The various dimensions as well as the cerebral landmarks were studied. The pyramidal tract is built up like a fan in the white matter by a thin layer of fibers of 2.8-3.5 mm in thickness. The fibers converge toward the internal capsule to a solid fiber tract with a lateral and apdiameter of 7.8 +/- 1.6 mm and 17.5 +/- 2.1 mm, respectively. This configuration of the PT presents different possibilities of damage during surgery. The evaluation of the three-dimensional course of the PT is possible by using three cerebral landmarks, the precentral gyrus, the entrance into the internal capsule and the posterior limb of the internal capsule. Their topography is described. Additionally the pyramidal tract can be defined medially by the sulcus cinguli and the roof of the lateral ventricle and laterally by the superior sulcus circularis Insulae. The possible displacement of the PT by space occupying lesions and the intra-operative orientation is discussed.

Adult↗
PubMed2004

Magnetic resonance imaging of mean values and anisotropy of electrical conductivity in the human brain.

The conductivity distribution in the human brain is difficult to obtain by conventional impedance tomography methods, in which currents are applied via surface electrodes. In this study, we obtained images of anisotropic conductivity in the human brain using diffusion magnetic resonance imaging (MRI). Diffusion-weighted images of the brain were acquired by a 1.5 T MRI system using an echo planar imaging sequence. Motion-probing gradients (MPGs) were applied with 25 arrayed b-factors up to 5000 s/mm2. The fast and slow diffusion components were estimated by fitting a biexponential attenuation function to the measured signals. The effective conductivities in each direction were calculated from the fast diffusion components. The mean conductivities of the cortex, the corpus callosum, and the internal capsule were 0.10 +/- 0.03 S/m, 0.12 +/- 0.02 S/m, and 0.08 +/- 0.01 S/m, respectively. Tissues with highly anisotropic cellular structures, such as the corpus callosum and the internal capsule, exhibited high anisotropy in conductivity. The anisotropy indices in the cortex, the corpus callosum, and the internal capsule were 0.07 +/- 0.03, 0.60 +/- 0.07, and 0.65 +/- 0.05, respectively.

Anisotropy↗
PubMed1994

[MRI of paraventricular white matter lesions in amyotrophic lateral sclerosis--analysis by diffusion-weighted images].

Magnetic resonance images in some cases of amyotrophic lateral sclerosis (ALS) revealed abnormal signals in both the paraventricular white matter and in the posterior limbs of the internal capsule. We examined T2- and diffusion-weighted MR images of these lesions in 18 cases of ALS. There were symmetrical high-signal areas in the posterior limbs of the internal capsule in all of the cases. The high-signal areas in the internal capsule corresponded to the pyramidal tracts in the anatomical atlas by Talairach. In 5 of the cases of ALS, T2- weighted MR images showed discrete paraventricular white matter lesions as well. The mean age of the ALS patients with paraventricular white matter lesions was higher than that of the ALS patients without such lesions. Proton densities calculated from the conventional MR images were higher in both the capsular and paraventricular lesions. The diffusion coefficients perpendicular to the pyramidal tract in the internal capsula lesions were within the normal range, where as the diffusion coefficients in the paraventricular lesions were increased in all directions. Thus, diffusion anisotropy was lost in the paraventricular lesions. These findings are similar to those observed in the white matter lesions of cerebro-vascular origin. As a result, the pathology of the paraventricular lesions in ALS was confirmed to be different from that of the internal capsular lesions.

Aged↗
PubMed2006

Acute autonomic dysfunction contralateral to acute strokes: a prospective study of 100 consecutive cases.

Complex painful reflex syndrome is sometimes described in the chronic phase of stroke. Acute autonomic dysfunction (AAD), which is occasionally present in cases of acute stroke, has not been studied prospectively. The aim of the study was to investigate AAD on the hemibody contralateral to the lesion in the acute phase of stroke. One hundred consecutive patients (median age +/- interquartile range, 74 +/- 21; range 19-93; 51 women: 80 +/- 17 and 49 men: 70 +/- 17 years) in the acute phase of stroke were studied prospectively. Changes in skin temperature or coloration, diaphoresis, pain, or edema were noted in the first 3 days post-stroke. Associations between AAD and topography (cortical pre- and/or post-central, insular, corona radiata, basal ganglia, internal capsule, thalamus, and brainstem), age, gender, ischemic or hemorrhagic etiology, or the presence of sensorimotor deficits or ataxia were examined using the chi-squared or Fisher's exact test and logistic regression analysis. AAD was found in 71% of the patients and showed a significant positive association with the presence of a lesion in the post-central cortex (P = 0.037), internal capsule (P = 0.005), basal ganglia (P = 0.002), or insula (P = 0.011) and a negative association with the presence of a lesion in the brainstem (P = 0.004). Multivariate logistic regression analysis including all studied topographic variables showed that only brainstem lesions were significantly associated with a decreased risk of developing AAD (odds ratio = 0.08, 95% confidence interval: 0.01-0.69, P = 0.022). AAD was not associated with age, gender, the ischemic or hemorrhagic nature of the lesion, the side of lesion, hypertonic or hypotonic paresis, or hyperreflexia or hyporeflexia. AAD was found in association with sensory deficits (P = 0.001) and contralateral hyperkinesia (P = 0.004). Acute AAD is significantly more likely to occur in the presence of hemispheric lesions involving sensory pathways from the cortex to the internal capsule and insula and is significantly less prevalent in the presence of brainstem lesions.

Acute Disease↗
PubMedDate not supplied

A novel microporous polyurethane vascular graft: in vivo evaluation of the UTA prosthesis implanted as infra-renal aortic substitute in dogs.

A novel microporous polyurethane blood conduit developed at the University of Texas at Arlington was implanted as an infra-renal substitute in dogs. The prosthesis was fabricated by precipitating a solution of the polymer with dry nitrogen onto a rotating mandrel. The grafts were sterilized either by gamma radiation (series I) or ethylene oxide (series II); they were implanted for the following prescheduled periods: 4, 24, 48 hours, and 1 week (short-term) and 2, 4 weeks, 3 and 6 months (medium-term). The thrombohematological characteristics of each animal were evaluated prior to implantation and confirmed that the index of blood coagulability was normal. In the short-term group, five out of eight grafts were patent and three were partially occluded; four grafts in the medium-term group were patent; one was partially occluded; and three were thrombosed at retrieval. One week after implantation, the prostheses were surrounded by an external capsule, which was present mainly at the two anastomoses. The external capsule covered the entire graft at 3 months. No kinking of the grafts was observed and the presence of a mild yellow stain related to bilirubin uptake was detected at 2 weeks, 1, 3, and 6 months. Histological studies have revealed the formation of a thin internal capsule at both anastomoses, 2 weeks postimplantation, which was not anchored to the graft wall. In the medium-term group, the thrombosed grafts failed to develop an internal capsule, whereas the patent graft exhibited a thick internal capsule made of neocollagenous tissue over the entire graft. This new microporous polyurethane prosthesis did not perform satisfactorily as an infra-renal substitute in dogs and its in vivo stability requires further assessment. Thus, the concept of a polyurethane with closed pores does not achieve what was anticipated.

Animals↗
PubMed2000

Conserved developmental algorithms during thalamocortical circuit formation in mammals and reptiles.

The general patterns of early thalamocortical development follow a similar sequence in all mammals. Thalamocortical projections descend through the ventral thalamus, advance in the internal capsule amongst cells which already possess dorsal thalamic projections, then reach the cerebral cortex by associating with subplate cells and their early corticofugal projections. Initially, the thalamic projections pause in the internal capsule and subplate layer. The interactions of the thalamocortical projections with the early generated, largely transient cells of the subplate, marginal zone, internal capsule and ventral thalamus are believed to play a crucial role in the organized deployment of thalamic projections and establishing a functional cortical architecture. Selective fasciculation, contact guidance and release of neurotrophic factors are thought to play roles in the development of thalamocortical projections. These ideas are obtaining support from recent work on reeler and other strains of mice. The evolutionary origin of these largely transient cells and the overlying logic of early developmental steps are not understood. The behaviour of the thalamocortical and corticothalamic projections at the corticostriatal junction is particularly puzzling. The comparison of early forebrain development in mammals and reptiles is beginning to reveal highly conserved cellular and molecular interactions during early thalamocortical development and to reveal homologies between telencephalic subdivisions.

Algorithms↗
PubMed2004

Diffusion tensor imaging as potential biomarker of white matter injury in diffuse axonal injury.

BACKGROUND AND PURPOSE: Multiple biomarkers are used to quantify the severity of traumatic brain injury (TBI) and to predict outcome. Few are satisfactory. CT and conventional MR imaging underestimate injury and correlate poorly with outcome. New MR imaging techniques, including diffusion tensor imaging (DTI), can provide information about brain ultrastructure by quantifying isotropic and anisotropic water diffusion. Our objective was to determine if changes in anisotropic diffusion in TBI correlate with acute Glasgow coma scale (GCS) and/or Rankin scores at discharge. METHODS: Twenty patients (15 male, five Female; mean age, 31 years) were evaluated. Apparent diffusion coefficients (ADCs) and fractional anisotropy (FA) values were measured at multiple locations and correlated with clinical scores. Results were compared with those of 15 healthy control subjects. RESULTS: ADC values were significantly reduced within the splenium (Delta18%, P =.001). FA values were significantly reduced in the internal capsule (Delta14%; P <.001) and splenium (Delta16%; P =.002). FA values were significantly correlated with GCS (r = 0.65-0.74; P <.001) and Rankin (r = 0.68-0.71; P <.001) scores for the internal capsule and splenium. The correlation between FA and clinical markers was better than for the corresponding ADC values. No correlation was found between ADC of the internal capsule and GCS/Rankin scores. CONCLUSION: DTI reveals changes in the white matter that are correlated with both acute GCS and Rankin scores at discharge. DTI may be a valuable biomarker for the severity of tissue injury and a predictor for outcome.

Adult↗
PubMed1990

Auditory ear extinction in lacunar syndromes.

A dichotic listening test was administered to 28 patients with lacunar syndromes in order to contribute to the investigation of the subcortical route of interhemispheric auditory pathways. Topographic study showed that lesions in the external capsule or in the anterior limb of the internal capsule in both hemispheres produced left ear extinction. The possibility that some of the auditory fibres travel through the external capsule, as well as the anterior limb of the internal capsule, before crossing the contralateral cerebral lobe is suggested.

Adult↗
PubMed1990

The organization of corticopontine fibres in man.

Patients with lesions located in the frontal and temporal lobes, in the parieto-temporo-occipital border zone, and in the anterior limb of the internal capsule, did not present ataxia or other cerebellar signs. On the other hand, patients with the ataxic hemiparesis (AH) syndrome had lesions located in the posterior limb of the internal capsule, in the corona radiata and in the central region of the cerebral cortex. These findings in man do not confirm the existence of large frontal (Arnold's bundle) and temporal (Türck's bundle) projections to the pontine nuclei and indicate that the main bulk of corticopontine fibres originates from the central region of the cerebral hemisphere and courses in the posterior limb of the internal capsule. In man, the anatomical organization of corticopontine fibres is therefore similar to that recently demonstrated in animals.

Cerebellar Ataxia↗
PubMed1991

Albumin outflow into deep cervical lymph from different regions of rabbit brain.

Dynamics and pathways of 125I-labeled albumin (RISA) outflow from brain to deep cervical lymph have been studied in anesthetized rabbits between 4 and 25 h after microinjection of 1 microliter RISA into the internal capsule or midbrain. Lymph from the jugular lymph trunks was collected for periods of 2-11 h. RISA was cleared from brain with half-times of disappearance from internal capsule and midbrain of 18.2 and 11.9 h, respectively. RISA was distributed in high concentration to subarachnoid arteries that supplied the tissue injection site; this was consistent with RISA drainage from brain via perivascular spaces. Outflow through lymph rose to a maximum value 15-20 h after tracer injection. Mean recovery of RISA from lymph over the 25-h collection period accounted for 22% of total loss from internal capsule and 18% from midbrain. This result compares with mean recoveries from caudate nucleus and cerebrospinal fluid of 47% and 30%, respectively [M.W.B. Bradbury, H.F. Cserr, and R.J. Westrop, Am. J. Physiol. 240 (Renal Fluid Electrolyte Physiol. 9): F329-F336, 1981]. These are minimal estimates of total outflow to lymph because of the 15- to 20-h delay in RISA passage from brain to lymph.

Animals↗
PubMed1994

[Brain development during the first year of life: quantitative assessment with ADC imaging].

Brain development during the first year of life was assessed quantitatively using apparent diffusion coefficient (ADC) images constructed from diffusion-weighted MR image data. The imaging plane was coronal at the section of the pons. The cerebral peduncle, internal capsule, corona radiata, superior longitudinal fasciculus and thalamus were selected for evaluation of their ADC values. A diffusion sensitive gradient was added in the anteroposterior direction. Thus the orientation of nerve fibers in the cerebral peduncle, internal capsule and corona radiata was perpendicular to it, and that in the superior longitudinal fasciculus was parallel to it. In neonates, the cerebral peduncle and internal capsule, having been moderately myelinated at birth, showed the slowest diffusion. The corona radiata and superior longitudinal fasciculus, having been unmyelinated at birth, showed the fastest diffusion. The thalamus had intermediate diffusion. These neonatal diffusions tended to be promptly restricted within the first five months, followed by additional slight restriction thereafter. ADC values in the first year were significantly reduced in all regions compared with those in the neonatal period, particularly in the corona radiata and thalamus. This study showed that ADC analysis can estimate normal brain development in detail and might be useful for investigating various neonatal brain diseases.

Brain↗
PubMed1998

Microstructural development of human newborn cerebral white matter assessed in vivo by diffusion tensor magnetic resonance imaging.

Alterations of the architecture of cerebral white matter in the developing human brain can affect cortical development and result in functional disabilities. A line scan diffusion-weighted magnetic resonance imaging (MRI) sequence with diffusion tensor analysis was applied to measure the apparent diffusion coefficient, to calculate relative anisotropy, and to delineate three-dimensional fiber architecture in cerebral white matter in preterm (n = 17) and full-term infants (n = 7). To assess effects of prematurity on cerebral white matter development, early gestation preterm infants (n = 10) were studied a second time at term. In the central white matter the mean apparent diffusion coefficient at 28 wk was high, 1.8 microm2/ms, and decreased toward term to 1.2 microm2/ms. In the posterior limb of the internal capsule, the mean apparent diffusion coefficients at both times were similar (1.2 versus 1.1 microm2/ms). Relative anisotropy was higher the closer birth was to term with greater absolute values in the internal capsule than in the central white matter. Preterm infants at term showed higher mean diffusion coefficients in the central white matter (1.4 +/- 0.24 versus 1.15 +/- 0.09 microm2/ms, p = 0.016) and lower relative anisotropy in both areas compared with full-term infants (white matter, 10.9 +/- 0.6 versus 22.9 +/- 3.0%, p = 0.001; internal capsule, 24.0 +/- 4.44 versus 33.1 +/- 0.6% p = 0.006). Nonmyelinated fibers in the corpus callosum were visible by diffusion tensor MRI as early as 28 wk; full-term and preterm infants at term showed marked differences in white matter fiber organization. The data indicate that quantitative assessment of water diffusion by diffusion tensor MRI provides insight into microstructural development in cerebral white matter in living infants.

Anisotropy↗
PubMed1994

Axons of early generated neurons in cingulate cortex pioneer the corpus callosum.

The internal capsule and corpus callosum are the two major efferent axonal pathways of the mammalian neocortex. Previous studies have shown that the first cortical axons to grow through the internal capsule, the pathway from cortex to its subcortical targets, are extended by subplate neurons, which are the earliest generated neurons in the neocortex. Here, we characterize the origin of the first axons to project through the other major efferent pathway of the cortex, the midline corpus callosum, which connects the two cortical hemispheres. Using anterograde Dil tracing, we show that cortical axons first cross the midline through the nascent corpus callosum at E17. Retrograde Dil labeling from medial cortex at E18 reveals that these axons originate from a discrete group of neurons in medial (presumptive cingulate) cortex. These early callosal cells have complex morphologies with highly branched dendrites and later appear to take on a pyramidal form characteristic of callosal neurons in deep layers of cingulate cortex. 3H-thymidine birthdating demonstrates that these cells are predominantly generated on E14, making them among the earliest generated neurons in this cortical region. Injections of retrograde tracers in one cortical hemisphere at late embryonic or early postnatal ages result in substantial numbers of neurons labeled in the ipsilateral subplate, but only a few neurons labeled in the contralateral subplate. Thus, subplate neurons do not pioneer or ever project in significant numbers through the corpus callosum. We conclude that the two major efferent pathways from cortex, the corpus callosum and the internal capsule, are pioneered by developmentally and spatially distinct populations of early generated cortical neurons.

Aging↗
PubMed2002

Changes in brain water diffusion during the 1st year of life.

PURPOSE: To evaluate the normal water diffusion changes that occur during the 1st year of life. MATERIALS AND METHODS: Diffusion-weighted imaging was performed in 40 subjects (age range, birth to 1 year) in whom both magnetic resonance imaging and neurologic assessment results were normal at the time of imaging and, where available, at follow-up. Apparent diffusion coefficient (ADC) was calculated in four areas of white matter (anterior and posterior subcortical and internal capsule) and four of gray matter (cortex, thalamus, head of the caudate nucleus, and lentiform nucleus). Linear regression was used to examine the effect of age on ADC, and analysis of variance was used to compare ADC within different brain regions. RESULTS: ADC decreased with age in all regions (P <.01). Data best fit with a logarithmic decline (r(2) = 0.20-0.63). ADC was significantly higher in white (113 x 10(-5) mm(2)/sec) than in gray matter (102 x 10(-5) mm(2)/sec; P <.001). Significant differences were seen among three white matter regions (subcortical, 188 x 10(-5) mm(2)/sec at birth; anterior limb of internal capsule, 130 x 10(-5) mm(2)/sec; posterior limb of internal capsule, 109 x 10(-5) mm(2)/sec) and three gray matter regions (cortex, 134 x 10(-5) mm(2)/sec at birth; head of caudate nucleus, 134 x 10(-5) mm(2)/sec at birth; and thalamus and lentiform nucleus, 120 x 10(-5) mm(2)/sec; P <.01). CONCLUSION: Results suggest that in neonates and infants, water diffusion is highly dependent on both subject age and brain location.

Age Factors↗
PubMed1986

Bilateral internuclear ophthalmoplegia with absence of convergent eye movements. Clinicopathologic correlation.

A case of bilateral internuclear ophthalmoplegia of long duration with autopsy confirmation is reported. The main features of the syndrome included paresis of ocular adduction upon attempted lateral gaze, horizontal nystagmus in the abducting eye, and an absence of converging eye movements. Examination of Weil-stained sections revealed multiple plaques of demyelination. The medial longitudinal fasciculus was demyelinated bilaterally in the upper pons-caudal midbrain. The oculomotor, trochlear, and abducens nuclei appeared relatively well preserved. The internal capsule was severely damaged. Large cyst-like structures were centered in the anterior limb bilaterally and extended caudally to the level of the genu. Plaques of demyelination were present bilaterally in the posterior limb. The left side of the internal capsule was more severely affected than the right. It is thought that convergence in this case may have been eliminated by interruption of fibers from the frontal eye fields and/or other cortical areas in their descent through the internal capsule.

Carcinoma, Small Cell↗