Cases reported "Dyslexia, Acquired"

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1/124. Lexical access via letter naming in a profoundly alexic and anomic patient: a treatment study.

    We report the results of a letter naming treatment designed to facilitate letter-by-letter reading in an aphasic patient with no reading ability. Patient M.R.'s anomia for written letters reflected two loci of impairment within visual naming: impaired letter activation from print (a deficit commonly seen in pure alexic patients who read letter by letter) and impaired access to phonology via semantics (documented in a severe multimodality anomia). Remarkably, M.R. retained an excellent ability to pronounce orally spelled words, demonstrating that abstract letter identities could be activated normally via spoken letter names, and also that lexical phonological representations were intact when accessed via spoken letter names. M.R.'s training in oral naming of written letters resulted in significant improvement in her oral naming of trained letters. Importantly, as M.R.'s letter naming improved, she became able to employ letter-by-letter reading as a compensatory strategy for oral word reading. M.R.'s success in letter naming and letter-by-letter reading suggests that other patients with a similar pattern of spared and impaired cognitive abilities may benefit from a similar treatment. Moreover, this study highlights the value of testing the pronunciation of orally spelled words in localizing the source of prelexical reading impairment and in predicting the functional outcome of treatment for impaired letter activation in reading.
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ranking = 1
keywords = visual
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2/124. Articulatory processes and phonologic dyslexia.

    BACKGROUND-OBJECTIVE: Grapheme-to-phoneme conversion (GPC) allows the pronunciation of nonword letter strings and of real words with which the literate reader has no previous experience. Although cross-modal association between visual (orthographic) and auditory (phonemic-input) representations may contribute to GPC, many cases of deep or phonologic alexia result from injury to anterior perisylvian regions. Thus, GPC may rely upon associations between orthographic and articulatory (phonemic-output) representations. METHOD-RESULTS-CONCLUSION: Detailed analysis of a patient with phonologic alexia suggests that defective knowledge of the position and motion of the articulatory apparatus might contribute to impaired transcoding from letters to sounds.
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ranking = 1
keywords = visual
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3/124. Visual paralexias in a Spanish-speaking patient with acquired dyslexia: a consequence of visual and semantic impairments?

    We report the case of a Spanish patient SC who misread 55 per cent of the single words shown to her. SC's reading accuracy was affected by word imageability and frequency. Nonword reading was very poor. The majority of SC's errors to real-word targets bore a close visual similarity to the items that elicited them, but there was no indication of an effect of serial position on the probability that a letter from a target word would be incorporated into the error made to that word. SC made some visual errors in object naming and also showed evidence of a general semantic impairment. We consider the similarity between SC and patient AB reported by Lambon Ralph and Ellis (1997), and suggest that the very high levels of visual errors shown by these two patients may reflect a combination of visual and semantic impairments.
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ranking = 8
keywords = visual
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4/124. Alexia for Braille following bilateral occipital stroke in an early blind woman.

    Recent functional imaging and neurophysiologic studies indicate that the occipital cortex may play a role in Braille reading in congenitally and early blind subjects. We report on a woman blind from birth who sustained bilateral occipital damage following an ischemic stroke. Prior to the stroke, the patient was a proficient Braille reader. Following the stroke, she was no longer able to read Braille yet her somatosensory perception appeared otherwise to be unchanged. This case supports the emerging evidence for the recruitment of striate and prestriate cortex for Braille reading in early blind subjects.
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ranking = 1.4665761004154
keywords = cortex
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5/124. Intact verbal description of letters with diminished awareness of their forms.

    Visual processing and its conscious awareness can be dissociated. To examine the extent of dissociation between ability to read characters or words and to be consciously aware of their forms, reading ability and conscious awareness for characters were examined using a tachistoscope in an alexic patient. A right handed woman with 14 years of education presented with incomplete right hemianopia, alexia with kanji (ideogram) agraphia, anomia, and amnesia. brain MRI disclosed cerebral infarction limited to the left lower bank of the calcarine fissure, lingual and parahippocampal gyri, and an old infarction in the right medial frontal lobe. Tachistoscopic examination disclosed that she could read characters aloud in the right lower hemifield when she was not clearly aware of their forms and only noted their presence vaguely. Although her performance in reading kanji was better in the left than the right field, she could read kana (phonogram) characters and Arabic numerals equally well in both fields. By contrast, she claimed that she saw only a flash of light in 61% of trials and noticed vague forms of stimuli in 36% of trials. She never recognised a form of a letter in the right lower field precisely. She performed judgment tasks better in the left than right lower hemifield where she had to judge whether two kana characters were the same or different. Although dissociation between performance of visual recognition tasks and conscious awareness of the visual experience was found in patients with blindsight or residual vision, reading (verbal identification) of characters without clear awareness of their forms has not been reported in clinical cases. Diminished awareness of forms in our patient may reflect incomplete input to the extrastriate cortex.
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ranking = 2.7332880502077
keywords = visual, cortex
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6/124. brain activation during reading in deep dyslexia: an MEG study.

    Magnetoencephalographic (MEG) changes in cortical activity were studied in a chronic Finnish-speaking deep dyslexic patient during single-word and sentence reading. It has been hypothesized that in deep dyslexia, written word recognition and its lexical-semantic analysis are subserved by the intact right hemisphere. However, in our patient, as well as in most nonimpaired readers, lexical-semantic processing as measured by sentence-final semantic-incongruency detection was related to the left superior-temporal cortex activation. Activations around this same cortical area could be identified in single-word reading as well. Another factor relevant to deep dyslexic reading, the morphological complexity of the presented words, was also studied. The effect of morphology was observed only during the preparation for oral output. By performing repeated recordings 1 year apart, we were able to document significant variability in both the spontaneous activity and the evoked responses in the lesioned left hemisphere even though at the behavioural level, the patient's performance was stable. The observed variability emphasizes the importance of estimating consistency of brain activity both within and between measurements in brain-damaged individuals.
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ranking = 0.73328805020772
keywords = cortex
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7/124. Neuropsychological evidence for case-specific reading: multi-letter units in visual word recognition.

    We describe a patient (GK) who shows symptoms associated with Balint's syndrome and attentional dyslexia. GK was able to read words, but not nonwords. He also made many misidentification and mislocation errors when reporting letters in words, suggesting that his word-naming ability did not depend upon preserved position-coded, letter identification. We show that GK was able to read lower-case words better than upper-case words, but upper-case abbreviations better than lower-case abbreviations. Spacing the letters in abbreviations disrupted identification, as did mixing the case of letters within words. These data cannot be explained in terms of letter-based reading or preserved holistic word recognition. We propose that GK was sensitive to the visual familiarity of adjacent letter forms.
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ranking = 5
keywords = visual
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8/124. Alexia with left homonymous hemianopia without agraphia. A case report with autopsy findings.

    Unusual findings at autopsy prompted this case report of a patient with the syndrome of alexia without agraphia. The expected disconnection of the left angular gyrus from both visual cortices was not found at postmortem examination. Multiple cerebral metastases were identified, but none were present in the presumed pathways connecting the left occipital lobe and the left angular gyrus.
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ranking = 1
keywords = visual
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9/124. Left hemiparalexia.

    Three patients with left splenial lesions made paralexic errors restricted to the left end of words. Errors appeared more frequently when a correct response was highly dependent on the initial letter of the stimulus. One patient had full visual fields with hemialexia affecting the left visual field. The other two patients had complete right hemianopia. We attribute left-sided reading errors in the hemianopic patients to a retinotopically restricted disconnection pattern that selectively disrupts transfer of information originating from the peripheral left visual field. Functional resistance of the more numerous transcallosal projections representing visual field adjacent to the vertical meridian may account for such a pattern. The emergence of positional reading errors from retinotopically restricted left hemifield disconnection suggests that callosal information transfer during normal reading may primarily involve elemental sensory rather than lexical/semantic information.
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ranking = 4
keywords = visual
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10/124. Tactile agnosia and tactile aphasia: symptomatological and anatomical differences.

    Two patients with tactile naming disorders are reported. Case 1 (right hand tactile agnosia due to bilateral cerebral infarction) differentiated tactile qualities of objects normally, but could neither name nor categorize the objects. Case 2 (bilateral tactile aphasia after operation of an epidural left parietal haematoma) had as severe a tactile naming disturbance as Case 1, but could categorize objects normally, demonstrating that tactile recognition was preserved. Case 1 may be the first case of tactile agnosia clearly differentiated from tactile aphasia. CT scans of Case 1 revealed lesions in the left angular gyrus, and in the right parietal, temporal, and occipital lobes. Case 2 had lesions in the left angular gyrus and of posterior callosal radiations. Our findings suggest that tactile agnosia appears when the somatosensory association cortex is disconnected by a subcortical lesion of the angular gyrus from the semantic memory store located in the inferior temporal lobe, while tactile aphasia represents a tactual-verbal disconnection.
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ranking = 0.73328805020772
keywords = cortex
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