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PubMed1985

Visual disturbances with focal progressive dementing disease.

Symptoms referable to the visual system may be the earliest and most prominent signs of idiopathic dementing disease (Alzheimer's type) despite the lack of objective signs in the eyes or visual system. Three such patients are described. The first patient, who had ultimately proven Alzheimer's disease, initially complained of poor vision and spatial disorientation. Her course was characterized by progressive topographic agnosia during a ten-year period. The second patient first sought ophthalmic consultation for blurring of vision that subsequently progressed during a six-year period to alexia without agraphia and spatial disorientation. The third patient, who had presumed Alzheimer's disease, initially complained of reading difficulties that prompted several ophthalmic consultations. Her problem was initially one of increasing visual agnosia which, together with other perceptive disturbances, gradually deepened during a period of several years.

Aged↗

PubMed2002

Disruption of posterior brain systems for reading in children with developmental dyslexia.

BACKGROUND: Converging evidence indicates a functional disruption in the neural systems for reading in adults with dyslexia. We examined brain activation patterns in dyslexic and nonimpaired children during pseudoword and real-word reading tasks that required phonologic analysis (i.e., tapped the problems experienced by dyslexic children in sounding out words). METHODS: We used functional magnetic resonance imaging (fMRI) to study 144 right-handed children, 70 dyslexic readers, and 74 nonimpaired readers as they read pseudowords and real words. RESULTS: Children with dyslexia demonstrated a disruption in neural systems for reading involving posterior brain regions, including parietotemporal sites and sites in the occipitotemporal area. Reading skill was positively correlated with the magnitude of activation in the left occipitotemporal region. Activation in the left and right inferior frontal gyri was greater in older compared with younger dyslexic children. CONCLUSIONS: These findings provide neurobiological evidence of an underlying disruption in the neural systems for reading in children with dyslexia and indicate that it is evident at a young age. The locus of the disruption places childhood dyslexia within the same neurobiological framework as dyslexia, and acquired alexia, occurring in adults.

Adolescent↗

PubMed2006

Right unilateral jargonagraphia as a symptom of callosal disconnection.

We report the case of a right-handed patient who exhibited right unilateral jargonagraphia after a traumatic callosal hemorrhage. The lesions involved the entire corpus callosum, except for the lower part of the genu and the splenium. The patient's right unilateral jargonagraphia was characterized by neologisms and perseveration in kanji and kana, and was more prominent in kana than kanji. The jargonagraphia was similar to that observed in crossed aphasia, except that agraphia occurred only with the right hand. The patient also showed right unilateral tactile anomia and right tactile alexia, along with right-ear extinction on a dichotic listening test for verbal stimuli, which suggested that language function was lateralized to the right hemisphere. Since this patient had learned to write with his right hand, kinesthetic images of characters were thought to be formed and stored dominantly in the left hemisphere. We suggest that the callosal lesions disturbed the interhemispheric transfer of information for the dual-route procedures for writing in the right hemisphere, allowing the kinesthetic images of characters stored in the left hemisphere to be processed freely, resulting in the right unilateral jargonagraphia. At least two factors seem to explain that kana was more defective than kanji. First, writing in kana, which is assumed to be processed mainly via a sub-word phoneme to grapheme conversion route, might depend more strongly on lateralized linguistic processing than writing in kanji. Second, kanji, which represent meaning as well as phonology, with much more complicated graphic patterns than kana, are assumed to be processed in both hemispheres.

Accidents, Traffic↗

PubMed1998

Associative visual agnosia resulting from a disconnection between intact visual memory and semantic systems.

We report the case of a patient (RC) who developed a severe visual agnosia, associated to alexia without agraphia, color anomia and amnesia, following an ischemic stroke in the territory supplied by the left posterior cerebral artery. Based on his proficient performance on tests evaluating analysis of elementary visual features, formation of viewer-centered and object-centered representations of visual stimuli and discrimination between drawings representing real and unreal objects, we concluded that the critical locus of deficit was a disconnection between the normally functioning visual memory store and the semantic system. RC's disturbance in visual processing of human faces paralleled his recognition disorder of other classes of objects. The possible contribution of neurobiological factors in determining RC's agnosic deficit is discussed.

Aged↗

PubMed2001

Door but not four and 4 a category specific transcoding deficit in a pure acalculic patient.

We report a left parietal damaged, acalculic, non aphasic patient who showed a specific deficit in reading Arabic and spelled-out numerals. Word reading was flawless, while he showed a severe impairment in reading meaningless strings of phonemes (phonological alexia). He also showed a dissociation between the preserved ability to retrieve knowledge about general facts and the impairment in retrieving cardinal, personal and non-personal numerical facts. These findings point to a separate organization in the brain of the numerical domain.

Aged↗

PubMed1979

Visual agnosia: the dual deficit of perception and recognition.

This case of visual agnosia is of special interest because of its causation by trauma, of the unusually long follow-up (10 1/2 years), and the evidence for dual deficits of recognition and perception. Although most of the findings were characteristic of associative visual agnosia with preserved perceptual function, the poor copying, contrasted to better spontaneous drawing, suggested apperceptive agnosia as well. Prosopagnosia, alexia without agraphia, Balint's syndrome, visual static agnosia and simultanagnosia were also observed. The patient had persisting amnestic syndrome, but no dementia or aphasia. The responses to visual stimulation were perseverations, form confusions and confabulations. Visual evoked potentials were severely, bilaterally abnormal and computerized tomographic localization showed bilateral lesions also. The stages of recognition are analysed through this case of visual verbal disconnection and the importance of memory in perception is highlighted.

Adult↗

PubMed1982

Calculation disturbances in adults with focal hemispheric damage.

It has been suggested that hemisphere-damaged patients with calculation disorders can be subdivided into 3 groups: agraphia or alexia for numbers, spatial dyscalculia and anarithmetia. The purpose of the present study was to evaluate the role played by visuospatial disorders and by anarithmetia in subjects with impaired calculation abilities. Seventy-six patients with focal hemispheric lesions and 26 normal controls with demonstrated ability to read and write numbers were given a written calculation task, the Token Test, the Crosses Test, a test of Constructional Apraxia and Raven's Progressive Matrices. In the calculation task, a quantitative score represented the number of digits that were correct numerically and put in correct position. A qualitative score with emphasis on visuospatial factors was obtained by scoring each problem with the criteria used in Benton's Visual Retention Test. Analysis of the results showed that both left and right hemisphere-damaged patients performed significantly worse than controls and that patients with left posterior lesions were particularly impaired even after correction of the acalculia scores by the results of the other neuropsychological tests. These results suggest that even though different factors may contribute to calculation disorders (impairment of intelligence, visuoconstructive difficulties and above all aphasia), left posterior lesions are particularly prone to produce an impairment in calculating abilities which is partially independent from the above disorders.

Aphasia↗

PubMed1986

Ideogram reading in normal and dyslexic children.

This study was concerned with the ideogram reading performances of groups of reading disabled and normal children. While adults with acquired alexia have associated defects in ideogram reading, all of the dyslexic children performed at normal adult levels. It was found that ideogram reading in control children is rather slow to develop, with only 7 and 8 year old subjects performing like normal adults; this is in contrast to other reading-related cognitive tasks in which normal performance develops earlier.

Adolescent↗

PubMed1993

Simultanagnosia as the initial sign of degenerative dementia.

In a study of 10 patients with degenerative brain disease that manifested as simultanagnosia, our aims were (1) to elucidate their clinical, neuropsychologic, and radiologic findings to determine whether these patients might represent a group distinguishable from those with typical Alzheimer's disease and (2) to help clinicians recognize this entity. All patients were initially examined by ophthalmologists because of visual difficulties, and the simultanagnosia remained undiagnosed until nonophthalmologic complaints developed. Optic ataxia developed in six patients, and all patients had mildly impaired eye movements. All 10 patients could identify colors appropriately. Nine patients had language deficits (anomia, decreased auditory comprehension, alexia, and agraphia) but were fluent and had relative preservation of sentence repetition, and four performed in the normal range on a test of associative fluency. Two patients scored in the normal range on memory tests, all had preserved insight, and nine had no family history of degenerative dementia. The mean age at onset of the disorder was 60 years (range, 50 to 69). Neuroimaging disclosed prominent bilateral occipitoparietal atrophy in nine patients and generalized atrophy in one. With this unusual but consistent clinical, neuropsychologic, and anatomic profile, these patients are clinically distinguishable from those with typical Alzheimer's disease, but until a specific cause has been found, we cannot be certain that they constitute a specific biologic entity. Clinicians should consider this diagnosis in relatively young patients who have slowly progressive nonocular visual complaints.

Aged↗

PubMed1999

Impaired face and word recognition without object agnosia.

A leading account of high-level visual recognition proposes that the recognition of faces, objects, and words is mediated by two processing capacities. Words are assumed to require the capacity to represent numerous parts, whereas faces are processed wholistically. and hence require the representation of complex units. Object recognition requires the capacity to represent both numerous and complex parts. As object recognition depends upon the same processing capacities underlying face and word recognition, this account predicts that patients with severe alexia and prosopagnosia should be deficient in tests of object recognition. We report a patient who is unable to recognize words or faces, yet performs relatively well on tests of object recognition. The two-capacity theory cannot accommodate this pattern of performance without additional assumptions.

Agnosia↗

PubMed1998

Paradoxically greater interhemispheric transfer deficits in partial than complete callosal agenesis.

Symptoms of interhemispheric disconnection are typically much less severe in callosal agenesis than after surgical section of the corpus callosum. Sperry [Sperry, R. W., Plasticity of neural maturation. Developmental Biology, 1968, 2 (Suppl.), 306-327.] has attributed this difference to two interconnected factors: (1) the callosal section is usually performed after the brain has lost the maximal degree of functional plasticity associated with the early stages of development and (2) the removal of an already formed structure is more disruptive for functional brain organization than the failure of the same structure to develop. It has been suggested that functional compensation is less efficient if callosal agenesis is partial rather than complete [Dennis, M., Impaired sensory and motor differentiation with corpus callosum agenesis: A lack of callosal inhibition during ontogeny? Neuropsychologia, 1976, 14, 455-469.]. This suggestion is supported by the present findings of partial left-hand anomia, partial left-field alexia and poor tactile cross-localization in a subject with a congenital absence of the posterior part of the corpus callosum due to an arteriovenous malformation. In agreement with many previous studies, similar, though more severe, symptoms of interhemispheric disconnection were found in a subject with a complete section of the corpus callosum, but not in a subject with complete callosal agenesis. Praxic control of the left hand on verbal commands was severely deficient in the callosotomy subject, but it was normal in the subject with callosal hypogenesis. The lesser degree of compensation in partial compared to complete callosal agenesis may be explained by a reduced pressure to develop extracallosal means of interhemispheric communication, contingent on the partial existence of callosal connections, as well as by the later occurrence in development of the causes of callosal hypogenesis compared to those of total callosal agenesis.

Agenesis of Corpus Callosum↗

PubMed2006

[Neuropsychological and magnetic resonance imaging findings in five patients after carbon monoxide poisoning].

INTRODUCTION: Carbon monoxide (CO) poisoning has been shown to result in cognitive impairments. These disorders have rarely been reported. The present study aimed to evaluate these disturbances in five patients with a neuroanatomical study. METHODS: There were two men and three women with an average of 25 years old. Patients were explored several months after acute CO poisoning. Neuropsychological testing was administered to assess memory, intellectual, executive, visual-spatial and constructional functions, language, praxis and gnosis. Cerebral magnetic resonance imaging (MRI) was performed in all patients using axial, sagittal and coronal slides with T1 and T2 weighted and flair images. None of the subjects had hyperbaric oxygen. They received 7, 5 mg bromocriptine per day. RESULTS: All patients presented cognitive disorders including marked impairment in long term memory with a severe defect in recall performance in comparison to recognition memory. Visual memory was more affected than the verbal one. There were also moderate disturbances in intellectual, executive, visual-spatial and constructional functions. One patient presented alexia agraphia, severe visual disturbances, constructional and dressing apraxia. Four patients had depression and one psychic akinesia. Cerebral MRI studies revealed that all patients had bilateral pallidal necrosis, bilateral hippocampal and moderate cortical atrophy. Fornix atrophy was found in 2 patients and corpus mammillary atrophy in 3 patients. Others lesions were also found: bilateral cerebellar in two cases and cortical in three cases. Treatment with bromocriptine was effective in three cases. There was no improvement in the patients treated 14 months and 5 years following CO poisoning. CONCLUSION: Neuropsychological impairments in CO poisoned subjects include memory, intellectual, executive, and visuospatial defects. In addition to pallidal necrosis, which is a typical feature of CO poisoning, hippocampal and cortical atrophy are often present. Bromocriptine can improve the cognitive disorders.

Adolescent↗

PubMed2001

Visual language and handwriting movement: functional magnetic resonance imaging at 3 tesla during generation of ideographic characters.

A functional magnetic resonance imaging experiment at 3 tesla was performed to investigate the collaborative mechanism between visuospatial processing and motor execution in performing visual language generation tasks. Japanese Kanji, ideographic characters, were utilized to design tasks. The bilateral border portions between the inferior parietal lobule and the occipital lobe were involved during a Kanji puzzle task, which required subjects to combine several parts into a Kanji. The higher motor areas, such as the premotor areas and the pre-supplementary motor areas, were also activated bilaterally during the puzzle task. The parieto-occipital activation may be related to analysis of configuration or segmentation/integration of Kanji figures. Activation in the higher motor areas may be induced by cognitive components related to motor function to perform the visuospatial language task, such as intense reference for displayed characters and finding a proper character for puzzle solution. A collaborative mechanism in these areas may explain the effectiveness of tactile reading in letter recognition by patients with pure alexia or kinesthetic facilitation by Kanji users when recalling difficult Kanji.

Adult↗

PubMed1986

Learning of disabled children and their environment.

It has been pointed out that cases of reading disability are rare in Japan due to the specificity of the language structure. Fifty children with learning disabilities were examined both neurologically and psychologically, and they were classified into three groups; the first group had alexia and agraphia (2 cases), 30 cases showing signs of minimal brain dysfunction with choreiform movements of the eyeballs comprised the second group and 18 cases with a history of asphyxia at birth and/or severe jaundice and clumsiness without choreiform movements of the eyeballs formed the third group. The children belonging to the second and third groups showed that the characteristic features of reading disability are related to their circumstances. The results showed that suitable dynamic guidance including their environment was necessary for them.

Adolescent↗

PubMed2001

Transient posterior encephalopathy induced by chemotherapy in children.

The cases of three children, 16, 12, and 12 years of age, who suffered sudden confusional state and cortical blindness lasting 12 to 30 minutes while under treatment with high-dose methotrexate, cyclophosphamide, and dactinomycin for a lower limb osteosarcoma are reported. Transient neuropsychologic deficits arose after the acute phase of treatment: left hemispatial neglect and constructive apraxia (Patient 1); constructive apraxia (Patient 2); and constructive apraxia and alexia without aphasia (Patient 3). The three patients recovered completely from all their deficits within the time frame of 3 hours to 2 weeks. Arterial hypertension and hypomagnesemia were found during the acute phase in all patients. In Patients 2 and 3, magnetic resonance imaging revealed increased parieto-occipital T(2) signal involving gray and white matter. In Patients 1 and 2, HmPAO-SPECT revealed parieto-occipital hypoperfusion that resolved a few days later. The alterations detected by neuroimaging were concurrent with the appearance and disappearance of the clinical symptoms. Such transient acute episodes have been named occipital-parietal encephalopathy. On the basis of our clinical, laboratory, and neuroimaging findings, an explanation for the origin of this syndrome, a migrainelike mechanism, triggered by chemotherapy-induced hypomagnesemia, is proposed.

Acute Disease↗

PubMed1999

Selective disorders of reading?

Over the past few decades, refined cognitive architectures with highly specific components have been proposed to explain apparently selective disorders of reading, resulting from brain disease or injury, in previously literate adults. Recent analysis of the more general linguistic and cognitive abilities supported by neural systems damaged in the various forms of alexia favours a rather different view of reading and the kinds of models sufficient to account for its acquisition, skilled performance and disruption.

Adult↗

PubMed2003

The myth of the visual word form area.

Recent functional imaging studies have referred to a posterior region of the left midfusiform gyrus as the "visual word form area" (VWFA). We review the evidence for this claim and argue that neither the neuropsychological nor neuroimaging data are consistent with a cortical region specialized for visual word form representations. Specifically, there are no reported cases of pure alexia who have deficits limited to visual word form processing and damage limited to the left midfusiform. In addition, we present functional imaging data to demonstrate that the so-called VWFA is activated by normal subjects during tasks that do not engage visual word form processing such as naming colors, naming pictures, reading Braille, repeating auditory words, and making manual action responses to pictures of meaningless objects. If the midfusiform region has a single function that underlies all these tasks, then it does not correspond to visual word form processing. On the other hand, if the region participates in several functions as defined by its interactions with other cortical areas, then identifying the neural system sustaining visual word form representations requires identification of the set of regions involved. We conclude that there is no evidence that visual word form representations are subtended by a single patch of neuronal cortex and it is misleading to label the left midfusiform region as the visual word form area.

Cognition↗

PubMed2003

Neurofeedback training for a patient with thalamic and cortical infarctions.

One year after a left posterior and thalamic stroke, a 52-year-old male participant was treated with 14 weeks of theta reduction neurofeedback training. Imaging studies revealed left temporal, parietal, occipital, and bilateral thalamic infarctions along the distribution of the posterior cerebral artery. Neuropsychological testing demonstrated severe verbal memory, naming, visual tracking, and fine motor deficits. Additionally, alexia without agraphia was present. A pretraining quantitative electroencephalograph (QEEG) found alpha attenuation, lack of alpha reactivity to eye opening, and excessive theta activity from the left posterior head region. Neurofeedback training to inhibit 4-8 Hz theta activity was conducted for 42 sessions from left hemisphere sites. Over the course of the training, significant reductions in theta amplitude occurred from the training sites as assessed from the post-session baseline periods. Posttraining, a relative normalization of the QEEG was observed from the left posterior head region.

Biofeedback, Psychology↗