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PubMed2002

Reorganization of speech production at the motor cortex and cerebellum following capsular infarction: a follow-up functional magnetic resonance imaging study.

Based on clinical data, Geschwind assumed left hemisphere dominance of speech production to extend to the cortical representation of articulatory and phonatory functions at the motor cortex. This author suggested, furthermore, that the clinical observation of rapid recovery from articulatory impairments after damage to the left-sided corticobulbar tracts reflects compensatory activation of an alternative pathway involving the contralateral pre-central gyrus and its efferent projections. In order to test this hypothesis, functional magnetic resonance imaging (fMRI) was performed 4 and 35 days after stroke in a 38-year-old man who had experienced sudden speech deterioration ('dysarthric speech') concomitant with weakness of the right upper limb and the right side of the face. Computerized tomography demonstrated an ischaemic infarction within the left internal capsule. The patient fully recovered from dysarthria within 9 days. Activation of the right hemisphere analogues of Broca and Wernicke areas has been assumed to contribute to recovery from aphasia. As a further aspect of the reorganization of speech function, the present case study demonstrates for the first time by means of fMRI a selective 'shift' of the cortical representation of speech motor control to the right Rolandic cortex and the left cerebellum during restitution of articulation in a case of transient dysarthria following infarction of the left internal capsule.

Adult↗
PubMed2004

Focal white matter density changes in schizophrenia: reduced inter-hemispheric connectivity.

Gray matter changes have been demonstrated in several regions in schizophrenia. Particularly, the frontal and temporal cortices and amygdala-hippocampal region have been found decreased in volume and density in magnetic resonance imaging (MRI) studies. These abnormalities may reflect an aberrant neuronal network in schizophrenia, suggesting that white matter fibers connecting these regions may also be affected. However, it is unclear if particular white matter areas are (progressively) affected in schizophrenia and if these are related to the gray matter changes. Focal white matter changes in schizophrenia were studied in whole brain magnetic resonance images acquired from 159 patients with schizophrenia or schizophreniform disorder and 158 healthy comparison subjects using voxel-based morphometry. White matter density changes in the patients with schizophrenia were correlated to gray matter density changes and to illness severity. In the patients with schizophrenia, significant decreases in white matter density were found in the genu and truncus of the corpus callosum in the left and right hemisphere, in the right anterior internal capsule and in the right anterior commissure. No interactions between diagnosis and age were found. Increased illness severity was correlated with low density of the corpus callosum and anterior commissure. Decreased corpus callosum density correlated with decreased density of thalamus, lateral inferior frontal and insular gray matter in patients and controls and with decreased density of medial orbitofrontal and superior temporal gyri in patients. Decreased internal capsule and anterior commissure density correlated with increased caudate, and globus pallidus density in patients and controls. These findings suggest aberrant inter-hemispheric connectivity of anterior cortical and sub-cortical brain regions in schizophrenia, reflecting decreased hemispheric specialisation in schizophrenia.

Adult↗
PubMed1992

[Short-latency somatosensory evoked potentials in patients with hypertensive intracerebral hemorrhage: clinical availability of N20 component].

Short-latency Somatosensory Evoked Potentials (SSEPs) were studied in 14 patients with putaminal hemorrhage and 17 patients with thalamic hemorrhage. After median nerve stimulation SSEPs were recorded from the electrodes placed on C3', C4' (2cm behind C3 or C4 of the internal 10-20 system respectively), and Cv7. (Reference was the linked ears.) Erb's potential was also recorded from the Erb's point using the contralateral one as the reference. The patients were classified into three groups according to central conduction time laterality index (CCT LI). CCT LI = (CCT on the affected side which is defined as the interpeak latency between N13 and N20)--(CCT on the non affected side). Group 1: CCT LI < or = 0.73 (it means within normal limit); Group 2: CCT LI > 0.73 (it means the significant latency delay of the N20 on the affected side); Group 3: CCT LI is not available (because the N20 was abolished on the affected side). We analyzed retrospectively the localization of the hematoma on CT scans, the degree of motor and sensory disturbance of the upper extremity in each group. Of the 14 patients with putaminal hemorrhage, 5 were in group 1; 3 were in group 2; 6 were in group 3. Patients in group 1 had a localized hematoma within the pallido-putamen complex. Patients in group 2 had a hematoma compressing the posterior limb of the internal capsule. Patients in group 3 had a hematoma involving the posterior limb of the internal capsule and had severer motor disturbance than those in group 1 or group 2.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2005

Lesion topography in capsulotomy for refractory anxiety--is the right side the right side?

OBJECTIVE: A previous report on bilateral capsulotomy in obsessive-compulsive disorder showed common topographic features of lesions in the right-sided internal capsule in all patients responding to the treatment. The aims of the present study were to test if the same region was involved in anxiety patients responding to surgery and to examine whether lesion area and site correlated with adverse events and effect on target symptoms. METHOD: Eleven anxiety patients who had undergone bilateral thermocapsulotomy were examined after 8-23 years. A quantitative MRI evaluation of the lesions within the internal capsule was conducted in three axial planes. RESULTS: None of the eight responders had lesions that corresponded to the earlier reported right-sided anatomical denominator. Four patients out of 11 were rated as having significant clinical symptoms indicating frontal lobe dysfunction. The total sum of the lesion area determined in each of the three anatomical levels did not correlate with the degree of anxiety reduction. However, the lesion area appeared to be related to a rating of executive dysfunctioning, apathy and disinhibition.

Adult↗
PubMed2006

Clinical correlates of cerebral water diffusion in Wilson disease.

OBJECTIVE: To investigate the course of diffusion changes in Wilson disease (WD) and to evaluate their clinical and radiologic correlates. METHODS: MRI with fluid-attenuated inversion recovery (FLAIR) and diffusion weighted images (DWI) were performed in 13 symptomatic patients with WD who had typical neurologic manifestations of the disease (sWD patients) and in 5 presymptomatic patients (psWD patients). Follow-up clinical and MRI data were obtained in 12/13 patients with sWD. Ten subjects without neurologic disease and with normal cerebral MRI were used as controls. Apparent diffusion coefficient (ADC) was measured in areas where hyperintense lesions were detected on FLAIR images and in the normal-appearing white matter. RESULTS: Hyperintense lesions were detected in all symptomatic patients on FLAIR MR images but only in 11 of 13 patients with sWD on DWI. These lesions were absent in patients with psWD. The mean ADC was found increased in the putamen, pallidum, internal capsule, mesencephalon, and within the white matter in the symptomatic group in comparison to controls. This was not observed in patients with psWD, who even had a decreased ADC in the putamen. A significant correlation was found between the increase in diffusion and the modified Rankin Scale in presence of symptoms. Moreover, the variation of the clinical scale was significantly correlated with the variation of diffusion in the putamen of symptomatic patients. CONCLUSION: A decrease in diffusion in the putamen can be detected before the occurrence of neurologic manifestations in WD. In contrast, a large increase in diffusion is detected after the occurrence of symptoms within the putamen, pallidum, internal capsule, and subcortical white matter parallel to the signal changes as seen on fluid-attenuated inversion recovery and diffusion weighted images.

Adolescent↗
PubMed1996

Evolution of the neuroimaging changes in fucosidosis type II.

We report on clinical and neuroradiological findings in two patients with fucosidosis type II; a 7-year-old Jordanian boy and a 3 1/2-year-old Anglo-Canadian girl. This rare, autosomal recessive disorder is caused by deficiency of lysosomal alpha-fucosidase and is manifested clinically by progressive mental and motor deterioration, coarse facies, growth retardation, recurrent infections, dysostosis multiplex, angiokeratoma corporis diffusum, visceromegaly and seizures. Cranial CT and magnetic resonance imaging showed density and signal abnormalities in the thalamus, globus pallidus and internal capsules bilaterally, as well as progressive CT density alterations in supratentorial white matter including the internal medullary laminae of the thalami and the internal capsules.

Brain↗
PubMed2002

A novel role for p75NTR in subplate growth cone complexity and visual thalamocortical innervation.

In cortical development, subplate axons pioneer the pathway from neocortex to the internal capsule, leading to the proposal that they are required for subsequent area-specific innervation of cortex by thalamic axons. A role for p75 neutrophin receptor (NTR) in area-specific thalamic innervation of cortex is suggested by the observation that p75NTR expression is restricted to subplate neurons in a low-rostral to high-caudal gradient throughout the period of thalamocortical innervation. In vitro, neurotrophin 3 binding to p75NTR increases neurite length and filopodial formation of immunopurified subplate neurons, suggesting a role for p75NTR in subplate growth cone morphology and function in vivo. Consistent with this idea, subplate growth cones have markedly fewer filopodia in mice lacking p75NTR than in wild type mice. Despite this gross morphologic defect, many subplate axons in knock-out mice pioneer the projection to the internal capsule as they do in wild-type mice. However a few subplate axons in the knock-out mice make ectopic projections rostral in the intermediate zone and frontal cortex. Concomitant with the altered morphology of subplate growth cones, mice lacking p75NTR have diminished innervation of visual cortex from the lateral geniculate nucleus, with markedly reduced or absent connections in 48% of knock-out mice. Thalamic projections to auditory and somatosensory cortex are normal, consistent with the gradient of p75NTR expression. Our present results are unusual in that they argue that p75NTR functions in a novel way in subplate neurons, that is, in growth cone morphology and function rather than in axon extension or neuronal survival.

Aging↗
PubMed2001

MRI findings in neuro-behçet's disease.

AIM: To evaluate the pattern and site of involvement in neuro-Behçet's disease (NBD). MATERIALS AND METHODS: Twenty-one patients with NBD were evaluated. Using 1.5T magnetic resonance imaging (MRI), T1-weighted axial and sagittal images, gadolinium enhanced axial and coronal images and T2-weighted axial images were obtained. RESULTS: The brainstem, basal ganglia, cerebral white matter, internal capsule, thalamus and spinal cord were involved in eighteen, nine, nine, seven, six and two patients, respectively. In nine patients with cerebral white matter involvement, four had subcortical involvement and three had periventricular involvement, in addition to two patients with focal deep white matter lesions. Among the brainstem lesions, pons involvement was seen in fourteen patients, all had ventrally located lesions, and nine had tegmental involvement. Midbrain involvement was seen in fourteen patients; the cerebral peduncle was involved in 11 of these. Five patients had brainstem atrophy: two cases were demonstrated at initial MRI, the other three cases were seen on follow-up MRI. Pyramidal signs, the most common neurological signs, were demonstrated in fourteen patients. Follow-up MRI was obtained 10 days to 20 months after the initial MRI in eight cases; all showed changes in size, shape and site of involvement. After gadolinium enhancement, thirteen patients demonstrated mottled non-confluent enhancement in the brainstem (eight patients), posterior limb of the internal capsule (three patients), pachymeninges (two patients) and spinal cord (two patients). CONCLUSION: NBD manifests a reversible course, but chronic NBD may result in brainstem atrophy. Characteristic involvement along the corticospinal tract is well correlated with neurological signs.

Adult↗
PubMed1986

[A new treatment of hypertensive intracerebral hematoma--a follow-up study on 46 patients with hematoma treated by CT guided stereotactic method].

During the last 2 years, 46 cases of hypertensive intracerebral hemorrhage in the basal ganglia were treated by CT guided stereotactic aspiration and their outcome was evaluated in terms of the rate of hematoma removal, the change of consciousness level and the recovery of motor and sensory functions. They are aged from 45 to 79 years old, the average 56, and aspirated 1 to 24 days after the onset, two third of them being within 1 week. The whole procedure was done in the CT room under direct CT guidance and by one trial. In putaminal type hemorrhage, the removed hematoma volumes ranged from 9 to 48 ml, average being 23.7 ml, in thalamic type from 5 to 29 ml, average being 15.5 ml. The average rate of removal was 81.1% in 30 cases within 1 week. In most cases, preoperative consciousness was not severely disturbed, in putaminal type, 19 were alert or confused, 4 somnolent, 5 stuperous and in thalamic type, 6, 6, 3 respectively and 2 were semicomatous, one of them had herniation sign. In putaminal type all but 2 cases recovered to alert or confused state, the first one had postoperative bleeding and the other was already apallic preoperatively. In thalamic type, we lost 3 cases, 2 by gastrointestinal bleeding and 1 DIC, by rehemorrhage 2 months after the operation. All but one who was semicomatous preoperatively recovered to alertness. In motor function, some cases of the putaminal bleeding with intact internal capsule remained hemiplegic. On the other hand, most of the cases with partial destruction of the internal capsule on CT recovered well in both types of hematoma.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed2005

Diffuse axonal injury in mild traumatic brain injury: a diffusion tensor imaging study.

OBJECT: Diffuse axonal injury (DAI) is a major complication of traumatic brain injury (TBI) that leads to functional and psychological deficits. Although DAI is frequently underdiagnosed by conventional imaging modalities, it can be demonstrated using diffusion tensor imaging. The aim of this study was to assess the presence and extent of DAI in patients with mild TBI. METHODS: Forty-six patients with mild TBI and 29 healthy volunteers underwent a magnetic resonance (MR) imaging protocol including: dual-spin echo, fluid-attenuated inversion recovery, T2-weighted gradient echo, and diffusion tensor imaging sequences. In 20 of the patients, MR imaging was performed at a mean of 4.05 days after injury. In the remaining 26, MR imaging was performed at a mean of 5.7 years after injury. In each case, mean diffusivity and fractional anisotropy were measured using both whole-brain histograms and regions of interest analysis. No differences in any of the histogram-derived measures were found between patients and control volunteers. Compared with controls, a significant reduction of fractional anisotropy was observed in patients' corpus callosum, internal capsule, and centrum semiovale, and there were significant increases of mean diffusivity in the corpus callosum and internal capsule. Neither histogram-derived nor regional diffusion tensor imaging metrics differed between the two groups. CONCLUSIONS: Although mean diffusivity and fractional anisotropy abnormalities in these patients with TBI were too subtle to be detected with the whole-brain histogram analysis, they are present in brain areas that are frequent sites of DAI. Because diffusion tensor imaging changes are present at both early and late time points following injury, they may represent an early indicator and a prognostic measure of subsequent brain damage.

Adolescent↗
PubMed1993

[A case of chronic thinner intoxication developing hyperkinésie volitionnelle three years after stopping thinner abuse].

We reported a 25-year-old male with chronic thinner intoxication. He had been sniffing thinner from the age of 15 to 20. Since the age of 20, he developed gait disturbance, weakness of lower extremities, and scanning speech. At the age of 23, three years after he stopped sniffing thinner, he had hyperkinésie volitionnelle (HV) of bilateral upper extremities. MRI study revealed diffuse high intensity areas in the cerebral white matter, thinning of the corpus callosum, and cerebellar and brainstem atrophy on T1 weighted images. On T2 weighted images, low intensity areas in the thalamus, the striatum, the anterior limb of the internal capsule, the tegmentum of midbrain, high intensity areas in middle cerebellar peduncle, the posterior limb of the internal capsule, the lateral part of the cerebral peduncle, and the cerebral white matter were noted. HV almost disappeared with 2.5 mg of clonazepam daily administered. The disappearance of HV by ischemic compression of his arm suggested that input from the periphery might be relevant to the etiology of HV. The time interval between exposure to thinner and the recognition of HV in our case was in agreement with that between the occurrence of cerebrovascular disease and the recognition of HV in the previous reports. We postulated that HV in this case was the manifestation of the denervation hypersensitivity in the dentatorubroolivary system.

Adult↗
PubMed2003

The parieto-collicular pathway: anatomical location and contribution to saccade generation.

The monkey lateral intraparietal area (LIP), involved in reflexive shifts of visual attention, has two main oculomotor outputs: towards frontal oculomotor areas and towards the superior colliculus. Recent studies suggest that these two outputs do not carry similar information. Direct LIP-collicular neurons would convey visual signals providing the oculomotor system with on-line visuo-spatial information. Parietal visuo-spatial information regarding internal stimuli would access the brainstem oculomotor circuitry through a parieto-frontal network. Consequently, an interruption of parieto-tectal neurons should affect reflexive saccades towards unpredictable targets and have little or no effect on saccades towards predictable or memorised stimuli. In order to test this hypothesis in humans, we have determined in rhesus monkeys the location of LIP-tectal fibres in the region of the internal capsule, and found that these neurons travel in the most posterior region of the posterior limb of the internal capsule. We have then tested, in seven patients with a small lesion involving this region, several oculomotor paradigms designed to determine the influence of spatial predictability on saccade accuracy and the ability to withhold reflexive saccades. In all patients, saccade accuracy was affected in unpredictable conditions but was normal when target location could be predicted or memorised. Reflexive saccade inhibition was affected only in the three patients in whom the capsular lesion had the most anterior extent. These results therefore support in humans the hypothesis that parieto-tectal neurons (i) transmit an on-line signal that is used by the oculomotor system for reflexive saccade triggering, (ii) are not crucial for the computation of internally guided saccades and (iii) are not crucial for reflexive saccade inhibition.

Adult↗
PubMed2000

Organization of radial and non-radial glia in the developing rat thalamus.

The organization of glia and its relationship with migrating neurons were studied in the rat developing thalamus with immunocytochemistry by using light, confocal, and electron microscopy. Carbocyanine labeling in cultured slice of the embryonic diencephalon was also used. At embryonic day (E) 14, vimentin immunoreactivity was observed in radial fascicles spanning the neuroepithelium and extending from the ventricular zone to the lateral surface of the diencephalic vesicle. Vimentin-immunopositive fibers orthogonal to the radial ones were also detected at subsequent developmental stages. At E16, radial and non-radial processes were clearly associated with migrating neurons identified by the neuronal markers calretinin and gamma-aminobutyric acid. Non-radial glial fibers were no longer evident by E19. Radial fibers were gradually replaced by immature astrocytes at the end of embryonic development. In the perinatal period, vimentin immunoreactivity labeled immature astrocytes and then gradually decreased; vimentin-immunopositive cells were only found in the internal capsule by the second postnatal week. Glial fibrillary acidic protein immunoreactivity appeared at birth in astrocytes of the internal capsule, but was not evident in most of the adult thalamic nuclei. Confocal and immunoelectron microscopy allowed direct examination of the relationships between neurons and glial processes in the embryonic thalamus, showing the coupling of neuronal membranes with both radial and non-radial glia during migration. Peculiar ultrastructural features of radial glia processes were observed. The occurrence of non-radial migration was confirmed by carbocyanine-labeled neuroblasts in E15 cultured slices. The data provide evidence that migrating thalamic cells follow both radial and non-radial glial pathways toward their destination.

Age Factors↗
PubMed1999

Utilization of impedance measurements in pallidotomy using a monopolar electrode.

OBJECT: This study was performed to evaluate the reliability and utility of using monopolar impedance monitoring for estimation of the location of the thermocouple electrode during a pallidotomy procedure. METHODS: In 26 patients, impedance profiles were measured at 2-mm intervals and anatomical boundaries were marked on postoperative MRI studies in 19 patients. The pattern of change in impedance as the electrode was towards the target coordinates in the globus pallidus was studied empirically in relation to MRI-defined anatomy and by electrical stimulations. The pattern of impedance change was of greater reliability than absolute impedance values. A drop in impedance was noted in 10 cases where the electrode entered the putamen or globus pallidus upon exiting the internal capsule, and in 9 of these this drop was measured before or at the distal boundary of the internal capsule. A variable pattern in the region of the base of the globus pallidus was observed, with 10 of 19 cases demonstrating a decrease and 8 cases an increase, consistent with the proximity of a CSF cistern in the former and the ansa lenticularis and optic tract in the latter. Simulations showed that the monopolar electrode was more sensitive to the approach of a boundary than the bipolar electrode. CONCLUSION: Our measurements and simulations suggest that a monopolar electrode could predict a nearby region of high or low impedance before penetrating it and a trend of decreasing impedance as the distal edge of the globus pallidus is approached.

Computer Simulation↗
PubMed1992

Magnesium and calcium contents in CNS tissues of amyotrophic lateral sclerosis patients from the Kii peninsula, Japan.

To further elucidate the involvement of metals as a factor in the pathogenesis of amyotrophic lateral sclerosis (ALS) on the Kii peninsula of Japan, a well-known high incidence area of ALS with low calcium and magnesium contents in soil and drinking water, we determined concentrations of these metals in samples of central nervous system tissue taken from postmortem ALS cases. Calcium content was determined by neutron activation analysis and magnesium by inductively coupled argon plasma emission spectrometry. From 5 ALS cases and 5 neurologically normal controls, we examined tissues from the precentral gyrus, including the motor cortex, internal capsule, crus cerebri and spinal cord, and from 22 other areas. The average calcium content in precentral gyrus, internal capsule, crus cerebri and spinal cord in ALS cases was higher than that in the controls, and the mean value of all 26 areas in the ALS cases was also higher than that of the controls. The average magnesium content of each region as well as the mean value of the 26 regions in the ALS cases was significantly lower than that in the controls. The Ca/Mg ratio of the 26 ALS regions was significantly higher than that of controls. This study strengthens our hypothesis that an abnormal metal metabolism plays a responsible role in the Ca-hydroxyapatite formation observed in central nervous system tissue of ALS cases, leading to motor neuron death and degeneration of the pyramidal tracts.

Adult↗
PubMed1990

[Two cases of brain infarction associated with hypertriglyceridemia].

We reported two cases of brain infarction. They were cousins. Case 1 was a 12-year-old girl, who complained of aphasia, dyscalculia, right-left disorientation and right homonymous hemianopsia. CT showed low density areas in left superior and middle temporal gyri. Case 2 was a 15-year-old boy, who had left hemiplegia and hypesthesia to pain, temperature and touch on the left side of the body. CT showed low density areas from the genu of the internal capsule to the corona radiata, and from the posterior portion of putamen to the posterior limb of the internal capsule on the right side. Both cases had hypertriglyceridemia which might be associated with the etiology of infarction.

Adolescent↗
PubMed1983

Brain stimulation reward in the lateral hypothalamic medial forebrain bundle: mapping of boundaries and homogeneity.

The boundaries and relative fiber concentration of the brain stimulation reward (BSR) sustaining system coursing through the lateral hypothalamic medial forebrain bundle (MFB) were mapped using a dorso-ventral moveable electrode. High response rates for BSR were found in a region extending dorso-ventrally from the zona incerta (ZI) to the base of the brain and medio-laterally from the fornix to the medial tip of the internal capsule (IC). Self-stimulation associated with perifornical area and self-stimulation associated with the tip of the internal capsule were mixed with aversion and forced movements, respectively. Current intensity threshold variations suggest: (i) that the reward system has a well-defined dorsal boundary ventral to the ZI, and (ii) that the core of the MFB contains a relatively higher concentration of reward relevant fibers than do its lateral, medial, dorsal and ventral components. No evidence was seen of independent mid-lateral and far-lateral MFB systems, though independent BSR sites in the dorsomedial and ventromedial hypothalamus were seen.

Animals↗
PubMed2000

Doxapram accentuates white matter injury in neonatal rats following bilateral carotid artery occlusion.

The effect of the respiratory stimulant, doxapram, on white matter damage was investigated in neonatal rats under cerebral ischemia. Five-day-old rats underwent bilateral carotid artery occlusion with or without 50 mg/kg i.p. of doxapram. Their brains were neuropathologically examined 48 h later. Doxapram induced about a 20% decrease of PCO(2) for 90 min, but did not cause any neuropathological abnormalities. Bilateral carotid artery occlusion resulted in mild cerebrocortical lesions in 67% of pups, and white matter lesions in the internal capsule in 44%. Doxapram, in addition to bilateral carotid artery occlusion, produced more severe white matter injury in the internal capsule (injury score; 0.67+/-0.87 vs. 1.70+/-0.48, P<0.05) and in the subcortical white matter (0.33+/-0. 67 vs. 1.10+/-0.54, P<0.05). These results demonstrated that the use of doxapram under an ischemic condition accentuates white matter damage in neonatal rats.

Animals↗