Medial Occipital Cortex Research Articles

Regional Cerebral Glucose Metabolism and its Association with Phenotype and Cognitive Functioning in Patients with Autism.

Introduction:In spite of three decades of neuroimaging, we are unable to find consistent and coherent anatomical or pathophysiological basis for autism as changes are subtle and there are no studies from India.Aim:To study the regional cerebral glucose metabolism in children with autism using positron emission tomography (PET) scan and to study the behavior and cognitive functioning among them.Materials and Methods:Ten subjects (8–19 years) meeting Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria for autism were evaluated on Childhood Autism Rating Scale (CARS), trail making test (TMT) A and B, Wisconsin card sorting test, Raven's progressive matrices, and PET scan. A control group of 15 matched subjects without any brain pathology or neurological disorder was similarly studied.Results:Four out of the ten patients with autism had abnormal PET scan findings, and in contrast, none of the patients in the control group had abnormal PET scan. Of the four patients with abnormality in the PET scan, two patients had findings suggestive of hypometabolism in cerebellum bilaterally; one patient showed bilateral hypometabolism in anterior temporal cortices and cerebellum, and the fourth patient had hypermetabolism in the bilateral frontal cortices and medial occipital cortices. Subjects with autism performed poorly on neuropsychological testing. Patients with abnormal PET scan findings had significantly higher scores on the “body use” domain of CARS indicating more stereotypy.Conclusion:Findings of this study support the view of altered brain functioning in subjects with autism.

Neural mechanisms for integrating consecutive and interleaved natural events.

To understand temporally extended events, the human brain needs to accumulate information continuously across time. Interruptions that require switching of attention to other event sequences disrupt this process. To reveal neural mechanisms supporting integration of event information, we measured brain activity with functional magnetic resonance imaging (fMRI) from 18 participants while they viewed 6.5-minute excerpts from three movies (i) consecutively and (ii) as interleaved segments of approximately 50-s in duration. We measured inter-subject reliability of brain activity by calculating inter-subject correlations (ISC) of fMRI signals and analyzed activation timecourses with a general linear model (GLM). Interleaving decreased the ISC in posterior temporal lobes, medial prefrontal cortex, superior precuneus, medial occipital cortex, and cerebellum. In the GLM analyses, posterior temporal lobes were activated more consistently by instances of speech when the movies were viewed consecutively than as interleaved segments. By contrast, low-level auditory and visual stimulus features and editing boundaries caused similar activity patterns in both conditions. In the medial occipital cortex, decreases in ISC were seen in short bursts throughout the movie clips. By contrast, the other areas showed longer-lasting differences in ISC during isolated scenes depicting socially-relevant and suspenseful content, such as deception or inter-subject conflict. The areas in the posterior temporal lobes also showed sustained activity during continuous actions and were deactivated when actions ended at scene boundaries. Our results suggest that the posterior temporal and dorsomedial prefrontal cortices, as well as the cerebellum and dorsal precuneus, support integration of events into coherent event sequences. Hum Brain Mapp 38:3360-3376, 2017. © 2017 Wiley Periodicals, Inc.

P273 Effect of repetitive transcranial magnetic stimulation on the structural connectome in patients with major depression

Introduction Repetitive transcranial magnetic stimulation (rTMS) of the dorsolateral prefrontal cortex (DLPFC) is an FDA-approved treatment for depression. Increasing evidence indicates that depression is accompanied by altered structural connectivity in the white matter. Objective We assess the impact of rTMS treatment for depression on the structural brain connectome. Patients and methods The IRB of Weill Cornell Medical College approved this study. 25 currently treatment-resistant depressed patients (age 21–68) participated in the study. Patients received 10-Hz rTMS over the left DLPFC 5 days/week for 5 weeks. Treatment response was assessed using the 24-item Hamilton Rating Scale for Depression (HAMD-24) at baseline and after the course of TMS. MRIs were acquired within 7 days prior to starting rTMS and within 3 days after the end of treatment. Diffusion tensor images were acquired using a single-shot spin echo imaging sequence. Nodes of the structural brain network were defined as the 96 anatomical brain areas in the Harvard-Oxford atlas. Whole brain deterministic streamline generation was performed using the Euler delta crossings tracking algorithm. A weighted connectivity matrix was generated based on the number of streamlines traversing between pairwise cortical regions. Graph theory metrics were calculated to assess network integration (characteristic path length), distribution (network density), segregation (clustering coefficient, modularity), and nodal influence (nodal degree, betweenness centrality). Results Relative to baseline, no change was observed post rTMS in the global network metrics of density, characteristic path length, and modularity. No group difference was observed between treatment responders and nonresponders on these global network metrics. Fig. 1 shows the distribution of nodes with properties that correlate (p Conclusion A collection of nodes in the frontal pole, frontal medial cortex, subcallosal cingulate, and lateral occipital cortex (LOC) have baseline nodal degree, centrality, and clustering coefficient that are correlated with baseline HAMD-24. The post treatment change in centrality in the LOC and precuneus is correlated with change in HAMD-24, suggesting rTMS selectively modulates the white matter connectivity underlying key areas in the default mode network. Download : Download high-res image (888KB) Download : Download full-size image

Posterior Reversible Encephalopathy Syndrome Triggerred By Alcohol Withdrawal

Posterior reversible encephalopathy syndrome (PRES) is a clinico-radiological entity characterized by headache, altered mental status, epileptic seizures, visual disturbances and typically transient changes in posterior cerebral circulation areas. In this article, we present a case of alcohol withdrawal accompanied by PRES. A 53-year-old male patient presented to the emergency department with visual hallucinations and meaningless speech. History from his relatives revealed that he has been consuming alcohol for about 35 years and the last consumption was 3 days before the admission. On neurological examination, there was limited cooperation and disorientation was evident to person, place and time. The speech was incoherent. No localizing sign was observed. Cranial magnetic resonance imaging (MRI) revealed bilateral hyperintense areas in medial occipital cortices and in subcortical white matter extending partly into parietal region. Treatment for alcohol withdrawal was started. Signs and symptoms regressed on the 7th day of the treatment as well as the lesions on MRI. The clinical presentation, characteristic MRI features together with the reversible nature of the syndrome suggest the diagnosis of PRES. The precise pathophysiological mechanism of PRES still remains unclear. Hypertension, clinical conditions that are associated with impaired cerebral auto-regulation as well as alcohol use which increases the levels of reactive oxygen species and nitric oxide may lead to the disruption of endothelial cells and blood-brain barrier breakdown. Overall, in our case, we think chronic alcoholism and alcohol withdrawal might have caused endothelial dysfunction leading to PRES.

Cross-Sectional and Prospective Associations Between β-Amyloid in the Brain and Chair Rise Performance in Nondementia Older Adults With Spontaneous Memory Complaints.

The objectives of this study were to examine the cross-sectional and prospective associations of muscle functional performance as assessed by a chair rise test and brain amyloid load among nondemented older adults with spontaneous memory complaints. This is a secondary analysis, with an observational design, using data from the MAPT randomized controlled trial. Individuals assessed for brain amyloid load (florbetapir F18 positron emission tomography) and without clinical dementia (N = 269 aged 75.2±4.2 years; 60.2% women) participated in the study. Cortical and regional standard uptake value ratios (SUVRs) were obtained. The main outcome measure was the 5-repetition chair rise performance (maximum speed-higher is better), which was assessed at baseline and at 6, 12, 24, and 36 months. Adjusted multiple linear (cross-sectional) and mixed-effect (overtime) regressions were performed. Any of mean cortical (regions of interest) and each regional SUVRs (anterior cingulate, anterior putamen, caudate, hippocampus, medial orbitofrontal cortex, occipital cortex, parietal cortex, pons, posterior cingulate, posterior putamen, precuneus, semioval center, and temporal cortex) were not associated to chair rise after adjustment for multiplicity. These findings were obtained for both cross-sectional and prospective associations. Brain amyloid was not found to be associated to chair rise performance in nondemented older adults with memory complaints. Potential mechanisms on the links, if any, of amyloid load with physical performance are probably not dependent on muscle function.

Feature-Selective Attentional Modulations in Human Frontoparietal Cortex

Control over visual selection has long been framed in terms of a dichotomy between "source" and "site," where top-down feedback signals originating in frontoparietal cortical areas modulate or bias sensory processing in posterior visual areas. This distinction is motivated in part by observations that frontoparietal cortical areas encode task-level variables (e.g., what stimulus is currently relevant or what motor outputs are appropriate), while posterior sensory areas encode continuous or analog feature representations. Here, we present evidence that challenges this distinction. We used fMRI, a roving searchlight analysis, and an inverted encoding model to examine representations of an elementary feature property (orientation) across the entire human cortical sheet while participants attended either the orientation or luminance of a peripheral grating. Orientation-selective representations were present in a multitude of visual, parietal, and prefrontal cortical areas, including portions of the medial occipital cortex, the lateral parietal cortex, and the superior precentral sulcus (thought to contain the human homolog of the macaque frontal eye fields). Additionally, representations in many-but not all-of these regions were stronger when participants were instructed to attend orientation relative to luminance. Collectively, these findings challenge models that posit a strict segregation between sources and sites of attentional control on the basis of representational properties by demonstrating that simple feature values are encoded by cortical regions throughout the visual processing hierarchy, and that representations in many of these areas are modulated by attention. Influential models of visual attention posit a distinction between top-down control and bottom-up sensory processing networks. These models are motivated in part by demonstrations showing that frontoparietal cortical areas associated with top-down control represent abstract or categorical stimulus information, while visual areas encode parametric feature information. Here, we show that multivariate activity in human visual, parietal, and frontal cortical areas encode representations of a simple feature property (orientation). Moreover, representations in several (though not all) of these areas were modulated by feature-based attention in a similar fashion. These results provide an important challenge to models that posit dissociable top-down control and sensory processing networks on the basis of representational properties.

Analysis of haptic information in the cerebral cortex.

Haptic sensing of objects acquires information about a number of properties. This review summarizes current understanding about how these properties are processed in the cerebral cortex of macaques and humans. Nonnoxious somatosensory inputs, after initial processing in primary somatosensory cortex, are partially segregated into different pathways. A ventrally directed pathway carries information about surface texture into parietal opercular cortex and thence to medial occipital cortex. A dorsally directed pathway transmits information regarding the location of features on objects to the intraparietal sulcus and frontal eye fields. Shape processing occurs mainly in the intraparietal sulcus and lateral occipital complex, while orientation processing is distributed across primary somatosensory cortex, the parietal operculum, the anterior intraparietal sulcus, and a parieto-occipital region. For each of these properties, the respective areas outside primary somatosensory cortex also process corresponding visual information and are thus multisensory. Consistent with the distributed neural processing of haptic object properties, tactile spatial acuity depends on interaction between bottom-up tactile inputs and top-down attentional signals in a distributed neural network. Future work should clarify the roles of the various brain regions and how they interact at the network level.

Characteristic distributions of CBF changes in remitted geriatric depression

BackgroundThe cerebral blood flow (CBF) is an absolute measure that superior to the relative measure of neural activity, blood oxygenation-level-dependent (BOLD). The previous studies have reported CBF abnormalities in the adult depressive patients. However, it is not clear whether the abnormal CBF could be improved in the remitted geriatric depression (RGD).MethodsWe enrolled 82 RGD patients and 90 age and education matched healthy controls. All the subjects underwent 3-T MRI with pseudo arterial spin labeling (pASL), and the pASL data were analysis voxel-by-voxel with control the gray matter volume.ResultsCompared with the healthy controls, the RGD patients demonstrated higher relative CBF value in left inferior temporal gyrus and left precuneus; while lower relative CBF value in right medial temporal and occipital cortex, right insula operculum (including parts of frontal, temporal and parietal cortex) and insula, right medial frontal cortex. When compared with the remitted early onset depression (EOD), the remitted late onset depression (LOD) showed lowed relative CBF value in right angular gyrus. While there was no significantly different relative CBF value between the RGD patients accompany with MCI and RGD patients with cognitive normal.ConclusionThe late life depression persists with CBF abnormalities in the remitted state. And it is implicit that hyperperfusion in the left brain cortex and hypoperfusion in the right brain cortex could be the specific form to RGD patients.Disclosure of interestThe authors have not supplied their declaration of competing interest.

Gray matter correlates of dopaminergic degeneration in Parkinson's disease: A hybrid PET/MR study using (18) F-FP-CIT.

Dopaminergic degeneration is a hallmark of Parkinson's disease (PD), which causes various symptoms affected by corticostriatal circuits. So far, the relationship between cortical changes and dopamine loss in the striatum is unclear. Here, we evaluate the gray matter (GM) changes in accordance with striatal dopaminergic degeneration in PD using hybrid PET/MR. Sixteen patients with idiopathic PD underwent (18) F-FP-CIT PET/MR. To measure dopaminergic degeneration in PD, binding ratio (BR) of dopamine transporter in striatum was evaluated by (18) F-FP-CIT. Voxel-based morphometry (VBM) was used to evaluate GM density. We obtained voxelwise correlation maps of GM density according to the striatal BR. Voxel-by-voxel correlation between BR maps and GM density maps was done to evaluate region-specific correlation of striatal dopaminergic degeneration. There was a trend of positive correlation between striatal BR and GM density in the cerebellum, parahippocampal gyri, and frontal cortex. A trend of negative correlation between striatal BR and GM density in the medial occipital cortex was found. Voxel-by-voxel correlation revealed that the positive correlation was mainly dependent on anterior striatal BR, while posterior striatal BR mostly showed negative correlation with GM density in occipital and temporal cortices. Decreased GM density related to anterior striatal dopaminergic degeneration might demonstrate degeneration of dopaminergic nonmotor circuits. Furthermore, the negative correlation could be related to the motor circuits of posterior striatum. Our integrated PET/MR study suggests that the widespread structural progressive changes in PD could denote the cortical functional correlates of the degeneration of striatal dopaminergic circuits. Hum Brain Mapp 37:1710-1721, 2016. © 2016 Wiley Periodicals, Inc.

Trait self-esteem and neural activities related to self-evaluation and social feedback.

Self-esteem has been associated with neural responses to self-reflection and attitude toward social feedback but in different brain regions. The distinct associations might arise from different tasks or task-related attitudes in the previous studies. The current study aimed to clarify these by investigating the association between self-esteem and neural responses to evaluation of one’s own personality traits and of others’ opinion about one’s own personality traits. We scanned 25 college students using functional MRI during evaluation of oneself or evaluation of social feedback. Trait self-esteem was measured using the Rosenberg self-esteem scale after scanning. Whole-brain regression analyses revealed that trait self-esteem was associated with the bilateral orbitofrontal activity during evaluation of one’s own positive traits but with activities in the medial prefrontal cortex, posterior cingulate, and occipital cortices during evaluation of positive social feedback. Our findings suggest that trait self-esteem modulates the degree of both affective processes in the orbitofrontal cortex during self-reflection and cognitive processes in the medial prefrontal cortex during evaluation of social feedback.

Association of Optic Radiation Integrity with Cortical Thickness in Children with Anisometropic Amblyopia.

Previous studies have indicated regional abnormalities of both gray and white matter in amblyopia. However, alterations of cortical thickness associated with changes in white matter integrity have rarely been reported. In this study, structural magnetic resonance imaging and diffusion tensor imaging (DTI) data were obtained from 15 children with anisometropic amblyopia and 15 age- and gender-matched children with normal sight. Combining DTI and surface-based morphometry, we examined a potential linkage between disrupted white matter integrity and altered cortical thickness. The fractional anisotropy (FA) values in the optic radiations (ORs) of children with anisometropic amblyopia were lower than in controls (P<0.05). The cortical thickness in amblyopic children was lower than controls in the following subregions: lingual cortex, lateral occipitotemporal gyrus, cuneus, occipital lobe, inferior parietal lobe, and temporal lobe (P<0.05, corrected), but was higher in the calcarine gyrus (P<0.05, corrected). Node-by-node correlation analysis of changes in cortical thickness revealed a significant association between a lower FA value in the OR and diminished cortical thickness in the following subregions: medial lingual cortex, lateral occipitotemporal gyrus, lateral, superior, and medial occipital cortex, and lunate cortex. We also found a relationship between changes of cortical thickness and white matter OR integrity in amblyopia. These findings indicate that developmental changes occur simultaneously in the OR and visual cortex in amblyopia, and provide key information on complex damage of brain networks in anisometropic amblyopia. Our results also support the hypothesis that the pathogenesis of anisometropic amblyopia is neurodevelopmental.

V1 surface size predicts GABA concentration in medial occipital cortex

A number of recent studies have established a link between behavior and the anatomy of the primary visual cortex (V1). However, one often-raised criticism has been that these studies provide little insight into the mechanisms of the observed relationships. As inhibitory neural interactions have been postulated as an important mechanism for those behaviors related to V1 anatomy, we measured the concentration of inhibitory gamma-amino butyric acid (GABA) in the medial occipital cortex where V1 is located using magnetic resonance spectroscopy (MRS) and estimated the surface area of V1 using fMRI retinotopic mapping. We found a significant positive relationship between GABA concentration and V1 surface area. This relationship was present irrespective of whether the MRS voxel had a fixed size across participants or was proportionally sized to each individual's V1 surface area. Hence, individuals with a larger V1 had a higher GABA concentration in the medial occipital cortex. By tying together V1 size and GABA concentration, our findings point towards individual differences in the level of neural inhibition that might partially mediate the relationships between behavior and V1 neuroanatomy. In addition, they illustrate how stable microscopic properties of neural activity and function are reflected in macro-measures of V1 structure.

Abnormal GABAergic function and face processing in schizophrenia: A pharmacologic-fMRI study

The involvement of the gamma-aminobutyric acid (GABA) system in schizophrenia is suggested by postmortem studies and the common use of GABA receptor-potentiating agents in treatment. In a recent study, we used a benzodiazepine challenge to demonstrate abnormal GABAergic function during processing of negative visual stimuli in schizophrenia. This study extended this investigation by mapping GABAergic mechanisms associated with face processing and social appraisal in schizophrenia using a benzodiazepine challenge. Fourteen stable, medicated schizophrenia/schizoaffective patients (SZ) and 13 healthy controls (HC) underwent functional MRI using the blood oxygenation level-dependent (BOLD) technique while they performed the Socio-emotional Preference Task (SePT) on emotional face stimuli (“Do you like this face?”). Participants received single-blinded intravenous saline and lorazepam (LRZ) in two separate sessions separated by 1–3weeks. Both SZ and HC recruited medial prefrontal cortex/anterior cingulate during the SePT, relative to gender identification. A significant drug by group interaction was observed in the medial occipital cortex, such that SZ showed increased BOLD signal to LRZ challenge, while HC showed an expected decrease of signal; the interaction did not vary by task. The altered BOLD response to LRZ challenge in SZ was significantly correlated with increased negative affect across multiple measures. The altered response to LRZ challenge suggests that abnormal face processing and negative affect in SZ are associated with altered GABAergic function in the visual cortex, underscoring the role of impaired visual processing in socio-emotional deficits in schizophrenia.

Where smart brains are different: A quantitative meta-analysis of functional and structural brain imaging studies on intelligence

Individual differences in general intelligence have been associated with differences in brain structure and function. The currently most popular theory of the neural bases of intelligence – the Parieto-Frontal Integration Theory of Intelligence (P-FIT) – describes a network of frontal and parietal brain regions as the main neural basis of intelligence. Here, we put the theory to an empirical test by conducting voxel-based quantitative meta-analyses of 12 structural and 16 functional human brain imaging studies, testing for statistically significant spatial convergence across studies. We focused our analyses on studies reporting associations between individual differences in intelligence (as assessed by established tests of psychometric intelligence) and either (a) brain activation during a cognitive task (functional meta-analysis) or (b) amount of grey matter as assessed by voxel-based morphometry (structural meta-analysis). The functional meta-analysis resulted in eight clusters distributed across both hemispheres, located in lateral frontal, medial frontal, parietal, and temporal cortices. The structural meta-analysis of VBM studies resulted in 12 clusters distributed in lateral and medial frontal, temporal, and occipital cortices, as well as in subcortical structures. Results of the functional and structural meta-analyses did not show any overlap — although both independently showed good match with the P-FIT. Based on the meta-analyses, we present an updated model for the brain bases of intelligence that extends previous models in also considering the posterior cingulate cortex and subcortical structures as relevant for intelligence, and in differentiating between positive and negative associations of intelligence and brain activation. From a critical review of original studies and methods, we derive important suggestions for future research on brain correlates of intelligence.

Reproducibility of phase rotation stimulated echo acquisition mode at 3T in schizophrenia: Emphasis on glutamine.

To determine the reproducibility and reliability of glutamine (Gln), measured with a very short echo time phase rotation stimulated echo acquisition mode (VTE-PR STEAM) sequence at 3T, in subjects with schizophrenia. Seven subjects with schizophrenia were scanned twice with VTE-PR STEAM in a Siemens 3T TIM Trio scanner with a 32-channel head coil. Spectroscopic data were collected from two voxels in gray matter, one in the dorsal anterior cingulate and the other in the medial occipital cortex. Reproducibility was assessed using coefficients of variation (CVs) and reliability with standard error of measurement and intraclass correlations (ICCs). Phantoms containing increasing concentrations of Gln in a physiologic solution of other neurometabolites with overlapping resonances were scanned to assess the validity of spectral Gln measurement. Very good reliability and reproducibility for Gln in both regions of interest were supported by CVs of ≤10.0% and ICCs of ≥0.6, respectively. Phantom studies documented a robust correspondence between known Gln concentrations and VTE-PR STEAM measurements of this metabolite (R(2) = 0.988). The VTE-PR STEAM approach at 3T permits the longitudinal assessment of Gln and other (1) H MR spectroscopy neurometabolites in a clinically plausible setting.

Dynamic magnetic source imaging of absence seizure initialization and propagation: A magnetoencephalography study

The present study aims to determine the initialization and propagation of typical absence seizures using magnetoencephalography (MEG). Fourteen drug-naïve children with childhood absence epilepsy (CAE) were studied using a 275-Channel MEG system. The spectral signatures of epileptic activity were assessed using Morlet continuous wavelet transform. Magnetic sources were volumetrically localized using dynamic magnetic source imaging (dMSI) with a slide window at a millisecond temporal resolution. The initial portion of ictal activity was predominantly located to the left frontal and posterior cortices. The frontal sources were in the left medial prefrontal cortex (MPFC), the pre-supplementary motor area (pre-SMA), the primary motor cortex, and the lateral prefrontal cortex. The posterior cortical sources were predominantly localized to the left precuneus (pC) and the medial occipital cortices (MOC). The ictal activity after the initialization showed involvement of the MPFC and pC of all patients (14/14) and recursive propagation between the frontal (MPFC) and posterior cortices (pC and MOC) via either the medial portion of the brain (9/14) or the thalamus (5/14), respectively. The left frontal and posterior (pC and MOC) cortices play a key role in the initialization of epileptic activity in absence seizures. The thalamus plays a key role in the propagation of absence seizures between the frontal and posterior cortical sources. Considering the MPFC and pC are the nodes of the default mode network (DMN), our results support involvement of the DMN in absence seizures.

Assessment of brain damage and plasticity in the visual system due to early occipital lesion: Comparison of FDG‐PET with diffusion MRI tractography

To determine the relation between glucose metabolic changes of the primary visual cortex, structural abnormalities of the corresponding visual tracts, and visual symptoms in children with Sturge-Weber syndrome (SWS). In 10 children with unilateral SWS (ages 1.5-5.5 years), a region-of-interest analysis was applied in the bilateral medial occipital cortex on positron emission tomography (PET) and used to track diffusion-weighted imaging (DWI) streamlines corresponding to the central visual pathway. Normalized streamline volumes of individual SWS patients were compared with values from age-matched control groups as well as correlated with normalized glucose uptakes and visual field deficit. Lower glucose uptake and lower corresponding streamline volumes were detected in the affected occipital lobe in 9/10 patients, as compared to the contralateral side. Seven of these 9 patients had visual field deficit and normal or decreased streamline volumes on the unaffected side. The two other children had no visual symptoms and showed high contralateral visual streamline volumes. There was a positive correlation between the normalized ratios on DWI and PET, indicating that lower glucose metabolism was associated with lower streamline volume in the affected hemisphere (R = 0.70, P = 0.024). We demonstrated that 18F-flurodeoxyglucose (FDG)-PET combined with DWI tractography can detect both brain damage on the side of the lesion and contralateral plasticity in children with early occipital lesions.

経静脈的および経動脈的に血行再建術をおこなった心臓粘液腫による脳塞栓症の1例

A 48-year-old woman with no previous neurological diseases was transferred to our hospital because of sudden-onset unconsciousness. On arrival, she showed consciousness disturbance (E1V1M3 on the Glasgow Coma Scale), tetraplegia, right conjugate deviation and bilateral pathological reflexes. These symptoms resulted in a NIH stroke scale score of 32. Brain diffusion-weighted MR imaging (DWI) showed multiple hyper-intense lesions, and MR angiography revealed occlusions of the basilar artery (BA) and superior branch of the right middle cerebral artery (MCA). Transthoracic echocardiography disclosed a 51 × 24 mm myxoma in the left atrium. These findings led to diagnosis of acute ischemic stroke due to embolization from cardiac myxoma. Thrombolytic therapy with intravenous tissue plasminogen activator (IV tPA) was started 120 min after onset because there were no contraindications for this treatment. However, the symptoms did not resolve, and thus endovascular therapy was performed immediately after IV tPA. Angiography of the left vertebral artery initially showed BA occlusion, but a repeated angiogram resulted in spontaneous recanalization of the BA. However, the left posterior cerebral artery remained occluded by a residual embolus. Subsequently, occlusion found in the superior branch of the right MCA was treated by intra-arterial local thrombolysis using urokinase and thrombectomy with a foreign body retrieval device, but the MCA remained occluded. DWI after endovascular therapy showed new hyper-intense lesions in the bilateral medial thalamus and left occipital cortex. Clinically, neurological status did not improve, with a score of 5 on the modified Rankin Scale. IV tPA can be used for stroke due to cardiac myxoma, but development of brain aneurysms and metastases caused by myxoma is a concern. Given the difficulty of predicting an embolus composite from a thrombus or tumor particle, aspiration thrombectomy may be safer and more effective for stroke due to cardiac myxoma to avoid delayed formation of brain aneurysms and metastases.

Low single dose gabapentin does not affect prefrontal and occipital gamma-aminobutyric acid concentrations

The γ-aminobutyric acid (GABA) system has been proposed as a target for novel antidepressant and anxiolytic treatments. Emerging evidence suggests that gabapentin (GBP), an anticonvulsant drug that significantly increases brain GABA levels, is effective in the treatment of anxiety disorders. The current study was designed to measure prefrontal and occipital GABA levels in medication-free healthy subjects after taking 0mg, 150mg and 300mg GBP. Subjects were scanned on a 3T scanner using a transmit-receive head coil that provided a relatively homogenous radiofrequency field to obtain spectroscopy measurement in the medial prefrontal (MPFC) and occipital cortex (OCC). There was no dose-dependent effect of GBP on GABA levels in the OCC or MPFC. There was also no effect on Glx, choline or N-acetyl-aspartate concentrations. The previously reported finding of increased GABA levels after GBP treatment is not evident for healthy subjects at the dose of 150 and 300mg. As a result, if subjects are scanned on a 3T scanner, low dose GPB is not useful as an experimental challenge agent on the GABA system.

Acute inferior homonymous quandrantanopia in a 71-year-old woman

A 71-year-old woman presented with acute inferior homonymous quadrantanopia initially mimicking acute ischemic stroke. As clinical signs and symptoms progressed to akinetic mutism with myoclonus the diagnosis of the Heidenhain variant of Creutzfeldt–Jakob disease was made. Brain MRI 4days after symptom onset revealed ribbon-like high signal intensity in the medial occipital cortex.