A case of Bilateral Perisylvian Syndrome with reading disability (original) (raw)
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Anomalous Cerebral Structure In Dyslexia Revealed With Magnetic Resonance Imaging
Archives of …, 1993
\s=b\ Objective.\p=m-\Todevelop quantitative methods for identifying cerebral anomalies on magnetic resonance images of subjects with language disorders and other learning disabilities. Design.\p=m-\Partially blinded comparison of subjects with dyslexia, unaffected relatives, and a control group balanced for age and socioeconomic status. Criterion standard: clinical diagnosis of dyslexia by physician or learning disabilities specialist on the basis of clinical assessment and family history. Settings.\p=m-\Hospitalpediatric neurology clinic and private reading clinic. Patients and Other Participants.\p=m-\Volunteers: individuals with dyslexia (seven male and two female, aged 15 to 65 years) from professional families; unaffected first-and second\x=req-\ degree relatives (four male and six female, aged 6 to 63 years) available in the geographical area; and controls (five male and seven female, aged 14 to 52 years). Interventions.\p=m-\Gradient echo three-dimensional scan in Seimens 1-Tesla Magnetom; 128 1.25-mm consecutive sagittal images. Main Outcome Measures.\p=m-\(1) Average length of the temporal (T) and parietal (P) banks of the planum temporale; (2) interhemispheric coefficients of asymmetry for T and P banks: Left-Right interhemispheric coefficients of asymmetry= (L-R)/[(L+R)/2]; (3) intrahemispheric coefficients of asym-metry=(T-P)/[(T+P)/2]; and (4) qualitative assessment of gyral variants in the parietotemporal operculum. Results.\p=m-\All groups had left-sided asymmetry for the temporal bank and right-sided asymmetry for the parietal bank. The group with dyslexia had exaggerated asymmetries, owing to a significant shift of right planar tissue from the temporal to parietal bank. They also had a higher incidence of cerebral anomalies bilaterally (subjects with dyslexia, six of nine; relatives, two of 10; and controls, zero of 12). Conclusions.\p=m-\Quantitative assessment of high-resolution magnetic resonance images can reveal functionally relevant variations and anomalies in cerebral structure. Further refinement of these measurement techniques should improve the diagnosis, classification, and treatment of language disorders and other learning disabilities. Early investigators believed that neuroanatomical cor
Cortex, 2010
Studies of dyslexia using diffusion tensor imaging (DTI) have reported fractional anisotropy (FA) differences in left inferior frontal gyrus (LIFG) and left temporo-parietal white matter, suggesting that impaired reading is associated with atypical white matter microstructure in these regions. These anomalies might reflect abnormalities in the left perisylvian language network, long implicated in dyslexia. While DTI investigations frequently report analyses on multiple tensor-derived measures (e.g., FA, orientation, tractography), it is uncommon to integrate analyses to examine the relationships between atypical findings. For the present study, semi-automated techniques were applied to DTI data in an integrated fashion to examine white matter microstructure in 14 children with dyslexia and 17 typically developing readers (ages 7-16 years). Correlations of DTI metrics (FA and fiber orientation) to reading skill (accuracy and speed) and to probabilistic tractography maps of the left perisylvian language tracts were examined. Consistent with previous reports, our findings suggest FA decreases in dyslexia in LIFG and left temporo-parietal white matter. The LIFG FA finding overlaps an area showing differences in fiber orientation in an anterior left perisylvian language pathway. Additionally,a positive correlation of FA to reading speed was found in a posterior circuit previously associated with activation on functional imaging during reading tasks. Overall, integrating results from several complementary semi-automated analyses reveals evidence linking atypical white matter microstructure in dyslexia to atypical fiber orientation in circuits implicated in reading including the left perisylvian language network.
Microstructure of temporo-parietal white matter as a basis for reading ability: evidence from DTI
European Psychiatry, 2002
A growing body of evidence suggests that dyslexia is a neurological disorder. A genetic basis for dyslexia has also been suggested (e.g., . Postmortem studies of dyslexic brains have discovered a consistent pattern of pathological changes (cortical microlesions and glial scars) throughout the left perisylvian cortices, along with reduced left-right asymmetry Stanford, California 94305 ‡ Scientific Learning Corporation of the planum temporale (Galaburda et al., 1985; Humphreys et al., 1990). Functional magnetic resonance im-Berkeley, California 94704 aging (fMRI) and positron emission tomography (PET) studies have found atypical activation patterns in the temporo-parietal cortex of adult dyslexics during read-Summary ing tasks, particularly on tasks involving the recoding of written symbols into their phonological counterparts Diffusion tensor magnetic resonance imaging (MRI) (Rumsey et al., 1992, 1997; Paulesu et al., 1996; Shaywitz was used to study the microstructural integrity of et al., 1998). Studies using magnetoencephalography white matter in adults with poor or normal reading (MEG) have also found differences in the time course of ability. Subjects with reading difficulty exhibited decortical processing in poor readers compared to normal creased diffusion anisotropy bilaterally in tempororeaders (Salmelin et al., 1996; Nagarajan et al., 1999). parietal white matter. Axons in these regions were
Common Brain Structure Findings Across Children with Varied Reading Disability Profiles
Scientific Reports
Data Consortium † Dyslexia is a developmental disorder in reading that exhibits varied patterns of expression across children. Here we examined the degree to which different kinds of reading disabilities (defined as profiles or patterns of reading problems) contribute to brain morphology results in Jacobian determinant images that represent local brain shape and volume. A matched-pair brain morphometry approach was used to control for confounding from brain size and research site effects in this retrospective multi-site study of 134 children from eight different research sites. Parietal operculum, corona radiata, and internal capsule differences between cases and controls were consistently observed across children with evidence of classic dyslexia, specific comprehension deficit, and language learning disability. Thus, there can be common brain morphology findings across children with quite varied reading disability profiles that we hypothesize compound the developmental difficulties of children with unique reading disability profiles and reasons for their reading disability.
Temporal lobe surface area measurements on MRI in normal and dyslexic readers
Neuropsychologia, 1993
In a neuroanatomical study of dyslexia, measurements were made of the superior surface of the temporal lobe (SSTL) on MRI scans in a sample of 17 dyslexics and 21 non-dyslexic subjects. Both anterior and posterior halves of the SSTL area showed significant leftward asymmetry in nondyslexics, but showed symmetry in dyslexics. The total SSTL area showed greater leftward asymmetry in non-dyslexics than in dyslexics. The dyslexics also revealed a significant correlation (r=0.69, P=O.O05) between Woodcock-Johnson Passage Comprehension scores and posterior SSTL asymmetry, such that those with higher scores had more leftward asymmetry. This suggests that among dyslexics the direction of SSTL asymmetry may serve as a risk Factor and/or a marker for the severity of reading comprehension problems.
Magnetic Resonance Imaging Findings for Dyslexia: A Review
Journal of Biomedical Nanotechnology, 2014
Developmental dyslexia is a brain disorder that is associated with a disability to read, which affects both the behavior and the learning abilities of children. Recent advances in MRI techniques have enabled imaging of different brain structures and correlating the results to clinical findings. The goal of this paper is to cover these imaging studies in order to provide a better understanding of dyslexia and its associated brain abnormalities. In addition, this survey covers the noninvasive MRI-based diagnostics methods that can offer early detection of dyslexia. We focus on three MRI techniques: structural MRI, functional MRI, and diffusion tensor imaging. Structural MRI reveals dyslexia-associated volumetric and shape-based abnormalities in different brain structures (e.g., reduced grey matter volumes, decreased cerebral white matter gyrifications, increased corpus callosum size, and abnormal asymmetry of the cerebellum and planum temporale structures). Functional MRI reports abnormal activation patterns in dyslexia during reading operations (e.g., aggregated studies observed under-activations in the left hemisphere fusiform and supramarginal gyri and over-activation in the left cerebellum in dyslexic subjects compared with controls). Finally, diffusion tensor imaging reveals abnormal orientations in areas within the white matter micro-structures of dyslexic brains (e.g., aggregated studies reported a reduction of the fraction anisotropy values in bilateral areas within the white matter). Herein, we will discuss all of these MRI findings focusing on various aspects of implemented methodologies, testing databases, as well as the reported findings. Finally, the paper addresses the correlation between the MRI findings in the literature, various aspects of research challenges, and future trends in this active research field.
Morphological Alteration of Temporal Lobe Gray Matter in Dyslexia: An MRI Study
Journal of Child Psychology and Psychiatry, 2000
Functional imaging studies of developmental dyslexia have reported reduced task-related neural activity in the temporal and inferior parietal cortices. To examine the possible contribution of subtle anatomic deviations to these reductions, volumes were measured for the major lobes of the brain, the subcortical nuclei, cerebellum, and lateral ventricles on magnetic resonance imaging (MRI) scans from 16 right-handed dyslexic men, ages 18 to 40, and 14 matched controls, most of whom had previously undergone PET imaging. A specific decrease in tissue volume was localized to the temporal lobes and was particularly prominent on the left ( p n01). An analysis of tissue composition revealed that this reduction was primarily attributable to decreased gray matter within the left temporal lobe (p n002). Further segmentation of the temporal lobe showed that this reduction was not confined to the superior temporal gyrus, the primary location of primary auditory cortex. Reductions of temporal lobe gray matter may reflect a regional decrease in neuronal number or neuropil, which in turn may result in reading impairment.
Brain structures associated with reading and their abnormalities in dyslexia: a whole-brain analysis
Developmental dyslexia (DD) is a highly prevalent neurodevelopmental disorder, which is devastating for individuals in modern societies in which fluent reading skill is mandatory for leading a normal life. Research on the neural origins of DD has continued for half a century, yielding, however, inconsistent results. It has also lacked a thorough characterization of the association between abnormal neuroanatomy and skills vital for reading. The current study was set out to determine abnormalities of grey and white matter volumes in adults with DD and associations between brain structures and reading and related skills. To this end, we conducted a whole-brain voxel based morphometry following current guidelines on state-of-the-art analysis approaches and rigorous neuropsychological testing. We found decreased volumes of grey matter in DD, comprising a left-hemispheric network including superior temporal and inferior frontal gyri, insula, the limbic system, and basal ganglia, and white...
Journal of Neurology, 2014
Congenital bilateral perisylvian syndrome (CBPS) presents with heterogeneous clinical manifestations such as pseudobulbar palsy, language disorder, variable cognitive deficits, epilepsy, and perisylvian abnormalities (most frequently polymicrogyria) on imaging studies. We investigated the relationship between seizures and extent of gray matter (GM) and white matter (WM) abnormalities using voxel-based morphometry (VBM) of brain magnetic resonance imaging (MRI) as well the association between seizures, structural abnormalities and cognitive ability. In this cross-sectional study, we evaluated 51 healthy volunteers and 18 patients with CBPS with epilepsy (seizure group, n = 7) and without (non-seizure group, n = 11). We used VBM (SPM8/DARTEL) to investigate areas with excess and atrophy of both gray and white matter, comparing groups of patients with controls. Intellectual ability of patients was assessed by the WISC-III or WAIS-III. Both groups with CBPS and the control group were homogeneous with respect to gender (p = 0.07) and age (p = 0.065). Besides perisylvian polymicrogyria, the seizure group exhibited areas with GM and WM reduction including temporal, frontal, parietal and occipital lobes. In contrast, we identified fewer areas with GM and WM reduction in the non-seizure group. The seizure group presented worse intellectual performance (performance IQ and global IQ) than the non-seizure group. The seizure group presented with a more widespread pattern of cortical and sub-cortical abnormalities, as well as worse cognition. Our results suggest that patients with CBPS and epilepsy appear to have widespread neuronal damage that goes beyond the areas with MRI-visible perisylvian polymicrogyria.