Insular infarction in subdural hematoma: A case series and pathophysiologic review

Subdural hematoma (SDH) is among the most common conditions managed by neurologists and neurosurgeons. As SDH incidence rates increase, a wider spectrum of SDH related complications have become evident. We prospectively identified a series of three patients with similar patterns of ipsilateral insular diffusion weighted imaging (DWI) hyperintensity associated with subdural hematoma. Detailed chart review was performed, and cases are described in relation to anatomy and proposed pathophysiology of venous hypertension and arterial vasospasm. The DWI changes were evident in all cases where clinical deficits following SDH evacuation were out of proportion to computed tomography findings. Therefore SDH-associated insular infarction may be a marker of greater disease severity, and further study of management and outcomes is needed.     

Specificities of arterial spin labeling (ASL) abnormalities in acute seizure

PurposeArterial spin labeling (ASL) is a non-invasive tool measuring cerebral blood flow (CBF) and is useful to assess acute neurological deficit. While acute stroke presents as hypoperfused vascular territory, epileptic activity causes cortical hyperperfusion. Other neurological conditions exhibit hyperperfusion, like migraine or secondary “luxury perfusion” in strokes. Our objectives were to evaluate the usefulness and potential specificities of ASL in acute seizure and correlate it with electroencephalogram.Materials and methodsAmongst a cohort of patients with neurological deficit, addressed for suspicion of stroke, we retrospectively reviewed 25 consecutive patients with seizures who underwent magnetic resonance imaging (MRI) with ASL and electroencephalography (EEG). We compared them with a control group of patients with migraine and stroke secondary re-perfusion, exhibiting ASL hyperperfusion.ResultsLateralized cortical hyperperfusion (high relative CBF) was observed in all patients. Good topographic correlation with EEG was found in 18 patients (72%). Eight (32%) had hyperperfusion of ipsilateral pulvinar, 5 (20%) had hyperperfused contralateral cerebellar hemisphere, 16 (64%) presented diffusion abnormalities and 20 (80%) had underlying epileptogenic lesions. Pulvinar hyperperfusion was not observed in the control group, nor were diffusion abnormalities in migrainous patients. Contralateral cerebellar hyperperfusion was observed in two migrainous patient, without associated pulvinar activation, whereas all patients with cerebellar hyperperfusion in the study group had associated pulvinar activation.ConclusionsElevated CBF can be observed in the epileptogenic zone, ipsilateral pulvinar and contralateral cerebellum (diaschisis) in seizure. These abnormalities seem specific when compared with other causes of hyperperfusion. Arterial spin labeling can be highly effective in the differential diagnosis of strokes.     

White matter lesion severity in male and female patients with Fabry disease

In male patients with Fabry disease (FD), significant age-related cerebral white matter lesions (WMLs) can be found. Although characteristic symptoms including cerebrovascular events are highly prevalent also in females with FD, cerebral structural changes have not been investigated in female FD patients yet. The authors quantified the WML load of 13 male and 14 age-matched female patients with FD and could demonstrate a comparably high frequency and severity of WMLs in both groups.     

Regression of rnoyamoya vessels and hemodynamic changes after successful revascularization in childhood movarnova disease

Successful revascularization improves ischemic symptoms in the pediatric patients with moyamoya disease. However, it is not clear whether the revascularization prevents future intracranial hemorrhage from the residual moyamoya vessels. The purpose of this study is to investigate perioperative morphological and hemodynamic changes in the moyamoya vessels. Four pediatric patients (age < 15 years old) with bilateral moyamoya disease were selected for this study. To quantify the number of moyamoya vessels, T1-weighted transverse images at the level of the basal ganglia and the thalamus were selected and characteristic flow voids in the lentiform nucleus were counted. Resting CBF and cerebrovascular reserve capacity (CRC) were measured pre- and 1 year after surgery using Xenon-CT CBF method with acetazolamide test. The ratio of deep CBF/kortical CBF was calculated as an index of hemodynamic stress distribution. The one-year follow-up studies showed that 1) the number of moyamoya vessels decreased on the operative side, but did not change on the nonoperative sides in all cases; 2) the ratio of deep CBFkortical CBF decreased on the operative sides, but did not change in the non-operative sides; and 3) the CRC increased on both sides. This observation suggests the possibility that revascularization surgery may be effective for preventing the future risk of intracranial hemorrhage.     

White matter amyloid in Alzheimer's disease brain

Amyloid -protein (A) deposits in the white matter were investigated by the double immunohistochemical staining for A and neuritic, glial or vascular components. Reactive astroglia and neurite abnormality were absent around A deposits in the white matter (w-A) even those with a core. The association of w-A with blood vessels was not consistent. Aggregates of activated microglia were found to be the sole but a consistent accompaniment of A deposits even in the absence of other components such as neuron, synapse, neurite abnormality and reactive astroglia, as observed in the white matter. This suggests that the aggregates of activated microglia most likely represent one of the factors promoting the process of A deposition.     

White matter lesions and hippocampal atrophy in Alzheimer's disease

White matter lesions (WML) and hippocampal atrophy (HA) on MRI commonly co-occur in Alzheimer's disease (AD) and are thought to play a role in the etiology of AD. It is still not known whether WML and HA are independent or related. The authors investigated the relation between WML and HA in 179 patients with probable AD who had a cerebral MRI. A linear relation was found between WML and HA, especially for WML in the frontal and parieto-occipital regions. The results suggest that vascular pathology and typical AD pathology (HA) are related.     

Regional cerebral blood flow in pediatric moyamoya disease: age-dependent decline in specific regions

Thirteen pediatric patients (ages 4–13 years) who underwent surgical treatment were examined regarding their rCBF in the preoperative periods. The postoperative rCBF was measured 39 times in these 13 patients. Thirteen healthy normal subjects (ages from 6 to 21 years) were also examined. The rCBF in the operculum and in the frontal, parietal, and occipital lobes was measured with ¹³³Xe inhalation method and single photon emission computed tomography. In the parietal and occipital lobes, the preoperative rCBF had a negative and significant correlation with their ages, but not in the operculum or frontal lobe. However, subsequent to the surgical treatment, the rCBF increased significantly in the patients 5 years old or less, and then post-operative rCBF values had significant negative correlations with age in each region. Received: 10 September 1997     

Global brain hypoperfusion and oxygenation in amnestic mild cognitive impairment

BackgroundTo determine if global brain hypoperfusion and oxygen hypometabolism occur in patients with amnestic mild cognitive impairment (aMCI).MethodsThirty-two aMCI and 21 normal subjects participated. Total cerebral blood flow (TCBF), cerebral metabolic rate of oxygen (CMRO₂), and brain tissue volume were measured using color-coded duplex ultrasonography (CDUS), near-infrared spectroscopy (NIRS), and MRI. TCBF was normalized by total brain tissue volume (TBV) for group comparisons (nTCBF). Cerebrovascular resistance (CVR) was calculated as mean arterial pressure divided by TCBF.ResultsReductions in nTCBF by 9%, CMRO₂ by 11%, and an increase in CVR by 13% were observed in aMCI relative to normal subjects. No group differences in TBV were observed. nTCBF was correlated with CMRO₂ in normal controls, but not in aMCI.ConclusionsGlobal brain hypoperfusion, oxygen hypometabolism, and neurovascular decoupling observed in aMCI suggest that changes in cerebral hemodynamics occur early at a prodromal stage of Alzheimer's disease, which can be assessed using low-cost and bedside-available CDUS and NIRS technology.     

Differential responses in CBF and CBV to cocaine as measured by fMRI: Implications for pharmacological MRI signals derived oxygen metabolism assessment

Introduction

Cognitive performance-induced brain oxygen metabolism has been successfully measured by functional magnetic resonance imaging (fMRI) in human studies. The measurement of the cerebral metabolic rate of oxygen consumption (CMRO₂) is typically achieved by assuming a fixed coupling of cerebral blood flow (CBF) and cerebral blood volume (CBV) and by performing a separate experiment to assess the vascular response to a hypercapnic challenge. Psychoactive drugs may have directly effect on the cerebral vasculature, potentially confounding the interpretation of pharmacological MRI (phMRI) data. In this study, we tested the assumptions of the standard CMRO₂ calculation following the administration of cocaine, in order to test the validity of this measurement in phMRI studies. The initial transient state and later steady state CBF and CBV responses to a hypercapnic challenge were measured.

Methods

CBF and CBV responses were directly measured by fMRI using continuous arterial spin-labeling (ASL) and contrast-enhanced fMRI, respectively. The coupling between changes in CBF and CBV during a hypercapnic challenge was examined under normal conditions and following the administration of cocaine.

Results

A decoupling of changes in CBF and CBV was observed during the transient state immediately following the administration of cocaine, and an altered coupling of CBF and CBV was found during the steady state after cocaine injection.

Discussion

These data suggest caution in interpreting CMRO₂ measurements from phMRI studies and may also lead to an improved understanding of the complex neuronal and vascular mechanisms of drug action.     

White matter tracts lesions and decline of verbal fluency after deep brain stimulation in Parkinson's disease

Decline of verbal fluency (VF) performance is one of the most systematically reported neuropsychological adverse effects after subthalamic nucleus deep brain stimulation (STN‐DBS). It has been suggested that this worsening of VF may be related to a microlesion due to the electrode trajectories. We describe the disruption of surrounding white matter tracts following electrode implantation in Parkinson's disease (PD) patients with STN‐DBS and assess whether damage of fiber pathways is associated with VF impairment after surgery. We retrospectively analyzed 48 PD patients undergoing bilateral STN DBS. The lesion mask along the electrode trajectory transformed into the MNI 152 coordinate system, was compared with white matter tract atlas in Tractotron software, which provides a probability and proportion of fibers disconnection. Combining tract‐ and atlas‐based analysis reveals that the trajectory of the electrodes intersected successively with the frontal aslant tract, anterior segment of arcuate tract, the long segment of arcuate tract, the inferior longitudinal fasciculus, the superior longitudinal fasciculus, the anterior thalamic radiation, and the fronto striatal tract. We found no association between the proportion fiber disconnection and the severity of VF impairment 6 months after surgery. Our findings demonstrated that microstructural injury associated with electrode trajectories involved white matter bundles implicated in VF networks.     

Cerebral blood flow correlated with carotid blood flow in neurologically normal elderly with severe white matter lesions

Previous studies of white matter signal hyperintensity (WMSH) on T ₂-weighted MRI (magnetic resonance imaging) have shown it to he related to decreased cerebral blood flow (CBF). However, there have been few studies on the relationship of WMSH and the internal carotid blood flow (CaBF). Doppler ultrasound sonography is widely used for evaluation of CaBF. We analyzed the relationship between CBF, CaBF, and WMSH. The subjects had not suffered cerebral ischemic episodes although they had some risk factors for stroke. They received MRI and were classified into three groups, i.e. mild, moderate, and severe WMSH. The % stenosis of the internal carotid artery (ICA) was measured with angiography. Doppler sonography was used to measure the mean bilateral CaBF. The oxygen-15 steady-state technique and PET (positron emission tomography) were used to measure CBF. There were significant correlations between the % stenosis of ICA and the ipsilateral CaBF and between the % stenosis of ICA and hemispheric CBF. There was a significant relationship between CBF and CaBF in the severe WMSH group, remaining significant after partialling out of the effects of the % stenosis. This indicated that an atherosclerotic change of the cerebral artery occurred in a way that carotid vascular resistence and cerebrovascular resistence were 'proportional'.     

White matter abnormalities in Parkinson's disease patients with glucocerebrosidase gene mutations

Glucocerebrosidase gene mutations represent a genetic risk factor for the development of Parkinson's disease. This study investigated brain alterations in Parkinson's disease patients carrying heterozygous glucocerebrosidase gene mutations using structural and diffusion tensor magnetic resonance imaging. Among 360 Parkinson's disease patients screened for glucocerebrosidase gene mutations, 19 heterozygous mutation carriers (5.3%) were identified. Of these, 15 patients underwent a neuropsychological evaluation and a magnetic resonance imaging scan. Sixteen age‐ and sex‐matched healthy controls and 14 idiopathic Parkinson's disease patients without glucocerebrosidase gene mutations were also studied. Tract‐based spatial statistics was used to perform a white matter voxel‐wise analysis of diffusion tensor magnetic resonance imaging metrics. Mean fractional anisotropy values were obtained from white matter tracts of interest. Voxel‐based morphometry was used to assess gray‐matter atrophy. Cognitive deficits were found in 9 mutation carrier patients (60%). Compared with controls, Parkinson's disease patients carrying glucocerebrosidase gene mutations showed decreased fractional anisotropy in the olfactory tracts, corpus callosum, and anterior limb of the internal capsule bilaterally, as well as in the right anterior external capsule, and left cingulum, parahippocampal tract, parietal portion of the superior longitudinal fasciculus, and occipital white matter. Mutation carrier patients also had decreased fractional anisotropy of the majority of white matter tracts compared with Parkinson's disease patients with no mutations. No white matter abnormalities were found in Parkinson's disease patients without glucocerebrosidase gene mutations. No gray matter difference was found between patients and controls. In Parkinson's disease patients, verbal fluency scores correlated with white matter abnormalities. Parkinson's disease patients carrying glucocerebrosidase gene mutations experience a distributed pattern of white matter abnormalities involving the interhemispheric, frontal corticocortical, and parahippocampal tracts. White matter pathology in these patients may have an impact on the clinical manifestations of the disease, including cognitive impairment. © 2013 Movement Disorder Society     

Visual hallucinations, white matter lesions and disease severity in Parkinson's disease

OBJECTIVES: To determine if visual hallucinations in patients with Parkinson's disease are associated with an increased prevalence of white matter lesions. PATIENTS AND METHODS: Fifteen patients with (group 1) and 15 patients without (group 2) a history of visual hallucinations were studied. Both groups were matched for age. Magnetic resonance imaging was performed in all patients using standard T2 weighted Fast-Spin-Echo sequences. Assessment of cerebral white matter changes was performed using a modification of established criteria, with semiquantitative evaluation of periventricular and deep white matter changes. RESULTS: There was no significant group difference with regard to the total amount of white matter changes, nor was a group difference found between the amount or extent of periventricular hyperintensities or deep white matter lesions. Group 1 was significantly (P = 0.001) more disabled as evaluated by Hoehn/Yahr stage controlling for age and duration of disease. Mean increases in Hoehn/Yahr stage were not significantly greater in group 1 compared with group 2 at a 2-year follow-up examination (0.6 vs. 0.3, P = 0.166). CONCLUSION: Our data suggest that visual hallucinations are an indicator of a more aggressive course of the disease, but are not associated with a higher prevalence of global or occipital white matter lesions.     

Acute cocaine administation: effects on local cerebral blood flow and metabolic demand in the rat

Local cerebral blood flow and glucose utilisation were measured in both saline (n = 10) and cocaine (10mg/kg; n = 10) treated rats using [¹⁴C]iodoantipyrine and [¹⁴C]2-deoxyglucose quantitative autoradiography respectively. In control animals, the ratio of flow to metabolism was 1.40 (r = 0.92) for the 40 brain regions examined. Cocaine treatment altered neither the correlation (r = 0.83) nor the ratio (1.49). Thus, the fundamental relationship between CBF and metabolism remains intact following acute cocaine exposure.     

Haemodilution with dextran 40 and hydroxyethyl starch and its effect on cerebral microcirculation

Summary The effect of haemodilution with Ringer's solution, hydroxyethyl starch (HAES) 200/0.5 10% and dextran 40 on cerebral blood flow (CBF) was measured in ten cats by means of the hydrogen clearance technique. As expected from theoretical considerations the haemodilution effect was short and not significant with Ringer's solution, but was 25% with HAES and 35% with dextrane 40. The corresponding rise in CBF was significant in both the latter but not with Ringer's solution. CBF was similarly highly correlated with diminution of haematocrit (Hct). The different effects of the substances on CBF could all be explained by their different effects on the Hct. Data analysis, together with recent literature, suggests that the dominating factor determining CBF was the O₂-transport capacity, which in these experiments was in close relation to Hct. The results support the assumption that the increase of CBF by haemodilution is caused by a regulatory mechanism and not by a change of rheological parameters.     

White matter lesions - age-adjusted values for cognitively healthy and demented subjects

OBJECTIVES: To develop age-adjusted norms for white matter lesions (WML) and to differentiate dementia from mild cognitive impairment and normal aging. MATERIALS AND METHODS: 240 patients underwent a comprehensive clinical, neuropsychological and MRI examination. A scale was developed quantify WML in anatomically defined regions by rating size and frequency. FLAIR sequences were used to determine a global and a frontal score. The scores were correlated with the psychometric test results and the final clinical diagnosis: cognitively normal (CN), mild cognitive impairment (MCI), Alzheimer's Disease (AD), vascular dementia (VD). Age-adjusted curves for WML scores were calculated by means of a non-parametic smoothing method. RESULTS: WML scores of the whole cerebrum and the frontal lobe were significantly increased in vascular dementia as compared to CN, MCI and AD. Individual WML scores correlated significantly with age and neuropsychological test results. For the age range 55-72, the WML scores of VD were significantly different from those of CN, MCI and AD. CONCLUSIONS: Age-corrected WML load was significantly higher in vascular dementia as compared to MCI, AD and cognitively normals over a wide age range.     

Cerebellar and lobar blood flow in schizophrenia: A perfusion weighted imaging study

It is still not clear whether brain hemodynamics plays a role in the functional and structural alterations in schizophrenia, since prior imaging studies showed conflicting findings. In this study we non-invasively explored cerebral and cerebellar lobe perfusion in the largest population of participants with schizophrenia thus far studied with perfusion-weighted imaging (PWI). Forty-seven participants affected by schizophrenia and 29 normal controls were recruited. PWI images were acquired following the intravenous injection of a paramagnetic contrast agent. Regional cerebral blood volume (CBV), blood flow (rCBF), and mean transit time (MTT) were obtained with the block-Circulant Singular Value Decomposition (cSVD) for frontal, temporal, parietal, occipital, and cerebellar lobes, bilaterally. Perfusion parameters were separately obtained for both gray and white matter in each lobe. Subjects with schizophrenia showed no significant differences in perfusion parameters when compared with controls. Interestingly, inverse correlations between age at onset and occipital, frontal and cerebellar MTT and between length of illness and frontal CBV were found. Preserved cerebral and cerebellar perfusion in our chronic population may in part be due to the effects of antipsychotic treatment which may have normalized blood volume and flow. Hypoperfusion in relation to chronicity, particularly in the frontal lobe, has been observed in accordance with earlier studies using positron emission tomography.     

White matter tract alterations in Parkinson's disease patients with punding

ObjectiveTo assess brain white matter tract alterations in patients with Parkinson's disease and punding (PD-punding) compared with controls and PD cases without any impulsive-compulsive behaviour.MethodsForty-nine PD patients (21 PD-punding and 28 PD with no impulsive-compulsive behaviours) and 28 controls were consecutively recruited. Clinical, cognitive and psychopathological evaluations were performed. Diffusion tensor MRI metrics of the main white matter tracts were assessed using a tractography approach.ResultsCompared with controls, both PD groups showed white matter microstructural alterations of the left pedunculopontine tract and splenium of the corpus callosum. PD-punding patients showed a further damage to the right pedunculopontine tract and uncinate fasciculus, genu of the corpus callosum, and left parahippocampal tract relative to controls. When adjusting for depression and/or apathy severity, a greater damage of the genu of the corpus callosum and the left pedunculopontine tract was found in PD-punding compared with patients with no impulsive-compulsive behaviours.ConclusionsPD-punding is associated with a disconnection between midbrain, limbic and white matter tracts projecting to the frontal cortices. These alterations are at least partially independent of their psychopathological changes. Diffusion tensor MRI is a powerful tool for understanding the neural substrates underlying punding in PD.