Alexia and related reading disorders

Seeing is not believing

An 84-year-old woman with a history of dry age-related macular degeneration presented with an acute inability to read, but intact writing ability (pure alexia or alexia without agraphia). She denied any difficulty speaking, paresthesias, or hemiparesis. Her visual acuity was 20/20 in each eye. Macular examination, optical coherence tomography, and fluorescein angiography demonstrated the previously diagnosed macular drusen and geographic atrophy of the retinal pigment epithelium consistent with the dry form of age-related macular degeneration both eyes. Automated perimetry revealed a right homonymous hemianopsia. Neuroimaging confirmed a left occipital ischemic infarction with involvement of the splenium of the corpus callosum producing the classic disconnection syndrome of alexia without agraphia.

Alexia With and Without Agraphia: An Assessment of Two Classical Syndromes

Background:

Current cognitive models propose that multiple processes are involved in reading and writing.

Objective:

Our goal was to use linguistic analyses to clarify the cognitive dysfunction behind two classic alexic syndromes.

Methods:

We report four experiments on two patients, one with alexia without agraphia following occipitotemporal lesions, and one with alexia with agraphia from a left angular gyral lesion.

Results:

The patient with occipital lesions had trouble discriminating real letters from foils and his reading varied with word-length but not with linguistic variables such as part of speech, word frequency or imageability. He read pseudo-words and words with regular spelling better, indicating preserved use of grapheme-to-phoneme pronunciation rules. His writing showed errors that reflected reliance on ‘phoneme-to-grapheme’ spelling rules. In contrast, the patient with a left angular gyral lesion showed better recognition of letters, words and their meanings. His reading was better for words with high imageability but displayed semantic errors and an inability to use ‘grapheme-to-phoneme’ rules, features consistent with deep dyslexia. His agraphia showed impaired access to both an internal lexicon and ‘phoneme-to-grapheme’ rules.

Conclusion:

Some cases of pure alexia may be a perceptual word-form agnosia, with loss of internal representations of letters and words, while the angular gyral syndrome of alexia with agraphia is a linguistic deep dyslexia. The presence or absence of agraphia does not always distinguish between the two; rather, writing can mirror the reading deficits, being more obvious and profound in the case of an angular gyral syndrome.

Thalamic alexia with agraphia

Alexia with agraphia is defined as an acquired impairment affecting reading and writing ability. It can be associated with aphasia, but can also occur as an isolated entity. This impairment has classically been associated with a left angular gyrus lesion In the present study, we describe a case involving a patient who developed alexia with agraphia and other cognitive deficits after a thalamic hemorrhage. In addition, we discuss potential mechanisms of this cortical dysfunction syndrome caused by subcortical injury. We examined a patient who presented with alexia with agraphia and other cognitive deficits due to a hemorrhage in the left thalamus. Neuropsychological evaluation showed attention, executive function, arithmetic and memory impairments. In addition, language tests revealed severe alexia with agraphia in the absence of aphasia. Imaging studies disclosed an old thalamic hemorrhage involving the anterior, dorsomedial and pulvinar nuclei. Tractography revealed asymmetric thalamocortical radiations in the parietal region (left Collapse

Key Words

• agraphia with alexia
• diaschisis phenomenon
• thalamic lesion
• tract disconnection.

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Affiliation(s)

Fábio Henrique de Gobbi Porto Behavioral and Cognitive Neurology Unit, Department of Neurology and Cognitive Disorders Reference Center (CEREDIC)
Maria Isabel d'Ávila Freitas Behavioral and Cognitive Neurology Unit, Department of Neurology and Cognitive Disorders Reference Center (CEREDIC)
Maira Okada de Oliveira Behavioral and Cognitive Neurology Unit, Department of Neurology and Cognitive Disorders Reference Center (CEREDIC)
Leandro Tavares Lucato Department of Radiology, Clinical Hospital of University of São Paulo, São Paulo
Marco Orsini Neurology Department, Fluminense Federal University and Masters Program in Science Rehabilitation, UNISUAM, Rio de Janeiro
Sara Lúcia Silveira de Menezes Masters Program in Science Rehabilitation, UNISUAM, Rio de Janeiro
Regina Miksian Magaldi Memory and Aging Unit, Geriatric Service, Department of Clinical Medicine and Cognitive Disorders Reference Center, University of São Paulo School of Medicine, São Paulo SP, Brazil
Cláudia Sellitto Porto Behavioral and Cognitive Neurology Unit, Department of Neurology and Cognitive Disorders Reference Center (CEREDIC)
Sonia Maria Dozzi Brucki Behavioral and Cognitive Neurology Unit, Department of Neurology and Cognitive Disorders Reference Center (CEREDIC)
Ricardo Nitrini Behavioral and Cognitive Neurology Unit, Department of Neurology and Cognitive Disorders Reference Center (CEREDIC)

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Patterns of reading performance in acute stroke: A descriptive analysis

One of the main sources of information regarding the underlying processes involved in both normal and impaired reading has been the study of reading deficits that occur as a result of brain damage. However, patterns of reading deficits found acutely after brain injury have been little explored. The observed patterns of performance in chronic stroke patients might reflect reorganization of the cognitive processes underlying reading or development of compensatory strategies that are not normally used to read. Method: 112 acute left hemisphere stroke patients were administered a task of oral reading of words and pseudowords within 1–2 days of hospital admission; performance was examined for error rate and type, and compared to that on tasks involving visual lexical decision, visual/auditory comprehension, and naming. Results: Several distinct patterns of performance were identified. Although similarities were found between the patterns of reading performance observed acutely and the classical acquired dyslexias generally identified more chronically, some notable differences were observed. Of interest was the finding that no patient produced any pure semantic errors in reading, despite finding such errors in comprehension and naming.