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Query: UMLS:C0004134 (ataxia)
 15,886 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The underlying mechanism of visual agnosia and optic aphasia has not been fully elucidated, although a number of hypotheses have been proposed. Besides, the difference between these two conditions has been a matter of debate. We report here the result of neuropsychological evaluation in a case of associative visual agnosia evolving to optic aphasia. A 64-year-old right-handed patient was found to be disoriented and confused after undergoing the operation of gastrectomy. CT scan revealed a large infarction in the territory of left posterior cerebral artery. Since 3 weeks after onset, neuropsychological investigations were carried out during 5 months. He was alert and co-operative. Right homonymous hemianopia with macular sparing was noted, but his visual acuity was normal. There was neither a global deterioration of intellectual capacities nor aphasia. Most striking finding was his difficulty in identifying common objects and colours along with a profound alexia. Prosopagnosia was absent. Visual naming both for objects and line drawings was severely impaired. He was unable to describe or demonstrate the use of the objects which could not be named. Pointing to objects named by the examiner was also severely impaired. Although tactile naming was also impaired, both of auditory naming for environmental sounds and naming objects in response to verbal descriptions were preserved. While he was not able to copy the objects skillfully, matching of identical objects and matching objects to line drawings were normal. Clumsiness of coping was thought to be due to his constructional apraxia and visuomotor ataxia. Therefore, his deficit in visual domain was considered to be associative visual agnosia.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Visual agnosia evolving to optic aphasia--a case study]. 130 17

We report here a case of multiple sclerosis (MS) showing pure alexia. The patient was a 28 year-old, right-handed male student of medicine. He had been healthy prior to college, but when he tried to read the newspaper one morning in January of 1983, he suddenly became aware that he could not. He could speak fluently and had no disturbances of auditory comprehension. No signs of abnormality were noted in his writing ability. Thereafter, the patient occasionally experienced difficulty in reading, together with right homonymous hemianopsia. These symptoms, however, usually vanished following sleep. In April, 1984, the patient experienced headache and ataxia when walking, followed by repeated remission and exacerbation of the symptoms. Corticosteroid therapy produced complete disappearance of the headache and ataxia. In September of 1985, he was hospitalized at our department due to the clouding of consciousness accompanied by convulsions. Neurologically, no abnormalities of the ocular fundus were noted and Babinski's sign was negative, but left hemiplegia was observed. Neuropsychologically, his intelligence was normal and he had no difficulty in writing, but paralexia was noted. There were no disorders of spontaneous speech or auditory comprehension. Examination by CT scan and magnetic resonance imaging revealed a number of lesions in the white substance of the cerebrum, including the left occipital lobe. The abnormal signs seen radiographically vanished when cortical hormones were administered. It has been thought that the symptoms of multiple sclerosis are due mainly to disorders of the white substance, and that MS seldom produces symptoms of aphasia, due to the fact that the lesions in this disease are generally small.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[A case of multiple sclerosis with pure alexia]. 260 43

Alexia without agraphia is readily recognized in its pure (without other neurologic findings) but rare form. However, this deficit is more common when associated with other behavioral disturbances that result from trauma or cerebral infarction to the posterior cerebral hemispheres. Two cases presented with alexia without agraphia following infarction within the posterior cerebral artery territory. Because of initial confusion and disorientation the patients were diagnosed as demented and unsuitable for rehabilitation. Both subjects had a visual field deficit and color agnosia. Prosopagnosia, simultanagnosia, and ataxia of visual-motor control were also present. The second case was unusual because of pure word blindness associated with a right occipital lobe lesion. Only a few such cases have been reported in the literature worldwide. This paper demonstrates that careful delineation of cognitive deficits permits greater understanding of functional disorders with improved rehabilitation outcome.
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PMID:Alexia without agraphia and associated disorders: importance of recognition in the rehabilitation setting. 356 19

The behavioral and anatomic correlates of pure alexia were analyzed in 16 patients. Right homonymous hemianopia failed to appear in three patients, who had right achromatopsia instead. Color anomia and unilateral optic ataxia were seen in six patients. Memory defects were found in two patients. Visual agnosia was noted in two. No patient had visual disorientation. The crucial anatomic correlate of alexia was a lesion of the paraventricular white matter of the left occipital lobe, capable of compromising both interhemispheric and intrahemispheric visual pathways. The lesion associated with color anomia was in the mesial occipitotemporal junction of the left hemisphere.
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PMID:The anatomic basis of pure alexia. 668 30

Interest in progressive focal cerebral syndromes associated with classical degenerative diseases has increased in recent years. Descriptions of posterior cortical atrophy with progressive visual agnosia are relatively rare. We present 5 patients (2 women) ranging in age between 57 and 72 years old. In all cases symptoms began and progressed with no known etiology. All cases were sporadic. The main clinical signs are difficulty in recognizing objects, colors, persons or places; topographical disorientation and visual memory alterations; alexia, simultagnosia, loss of ocular fixing and optic ataxia. Some patients presented other disturbances of praxis or memory and 2 progressed to global dementia. Language function was preserved and behavioral disturbances did not develop. The amplitude of the P100 visual evoked potential was low but latency was normal in 4 patients and prolonged in 1. Brain images showed atrophy and hypoperfusion in the parieto-occipital area. The neuropathology status of these patients is unknown.
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PMID:[Posterior cortical atrophy with progressive visual agnosia]. 775 9

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.
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PMID:Simultanagnosia as the initial sign of degenerative dementia. 841 61

A 65-year-old woman with progressive visuospatial dysfunction for 2 years complained of later-onset associated memory impairment. MRI revealed diffuse cerebrocortical atrophy, which was especially severe in both parieto-occipital regions but spared the calcarine and pericalcarine cortices. Examination 5 years after onset revealed left visual hemi-neglect, oculomotor apraxia, optic ataxia, simultanagnosia, verbal alexia, lexical and spatial agraphia, and anterograde amnesia. This patient's disorder is considered in the context of previous reports on the array of cognitive disturbances associated with posterior cortical atrophy (pCA). Special emphasis is made on her reading and writing disturbances, because their prevalence and range of individual variability have not been established in pCA. This array of neuropsychological manifestations may help to distinguish among different clinical and etiological types of pCA, and to elucidate the pathophysiology of a syndrome that has been associated with conditions as diverse as Alzheimer's disease, subcortical gliosis, and prion diseases. The parameters described in our case may thus help to address these issues in clinico-pathological studies with large numbers of patients with pCA.
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PMID:Alexia and agraphia in posterior cortical atrophy. 911 97

Patients with posterior cortical atrophy may have dorsal visual system (occipital-parietal) dysfunction (optic ataxia, visuospatial disorientation, and simultanagnosia), ventral visual system (occipital-temporal) dysfunction (pure alexia, prosopagnosia, visual anomia, and agnosia), or both. We report a professional musician with ventral system dysfunction whose first symptom was alexia for music. Subsequently, she developed pure alexia for words but had preserved sorting of words. These observations suggest that the ventral visual system is important in music and word reading. However, sorting of words may be mediated by the dorsal visual system.
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PMID:Progressive ventral posterior cortical degeneration presenting as alexia for music and words. 952 Dec 52

Early alexia and higher visual impairments characterize Posterior cortical atrophy (PCA), a progressive dementing syndrome most often caused by Alzheimer disease. Posterior cortical atrophy is rare, and the nature of the visual impairments in PCA are unclear. The authors observed two patients who had an insidiously progressive reading difficulty characterized by letter-by-letter reading and otherwise intact cognitive functions. Over time, these patients developed "ventral simultanagnosia" with preserved detection of multiple stimuli but inability to interpret whole scenes. Subsequently, they progressed to Balint syndrome with "dorsal simultanagnosia," optic ataxia, and oculomotor apraxia. Structural imaging was normal, but functional imaging revealed posterior cortical dysfunction. On a letter reading task, both patients had a word superiority effect, and on a whole word reading task, they could not read most words with missing or crosshatched letters. An inability to assess whole scenes progressed to an inability to detect more than one stimulus in an array. These findings suggest an evolution of PCA with progressive difficulty in visual integration beginning with letters, progressing to whole scenes, and culminating in Balint syndrome. These changes may reflect an extension of the pathophysiology of PCA from the extrastriate visual cortex to its occipitotemporal and occipitoparietal connections.
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PMID:The evolution of alexia and simultanagnosia in posterior cortical atrophy. 965 88

Lesions of extrastriate cortex cause selective defects in visual function. Damage to portions of the "ventral stream" in medial and inferior occipitotemporal cortex lead to impaired perception of color or various specific visual object recognition defects, such as prospagnosia, the inability to recognize familiar faces, and alexia, the inability to read. The latter must be distinguished from a variety of other reading defects related to primary visual, attentional, linguistic, or ocular motor impairments. Damage to the "dorsal stream" in lateral occipito-temporo-parietal regions impairs visuospatial capabilities, leading to akinetopsia (impaired motion perception) or Balint's syndrome, a loosely bound triad of simultanagnosia, optic ataxia, and ocular motor apraxia. Topographagnosia can occur with ventral or dorsoal lesions for different reasons. Considerable evidence has accumulated showing that residual vision or even "blindsight," which is visual perception in the absence of awareness, can persist after lesion of striate cortex in some patients.
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PMID:Deficits in cortical visual function. 1137 May 68


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