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

Published online by Cambridge University Press:  02 December 2014

Claire A. Sheldon ,
George L. Malcolm  and
Jason J.S. Barton
Claire A. Sheldon
Affiliation:
Department of Medicine (Neurology), Ophthalmology and Visual Science, and Psychology, University of British Columbia, Vancouver, BC, Canada
George L. Malcolm
Affiliation:
Department of Medicine (Neurology), Ophthalmology and Visual Science, and Psychology, University of British Columbia, Vancouver, BC, Canada
Jason J.S. Barton*
Affiliation:
Department of Medicine (Neurology), Ophthalmology and Visual Science, and Psychology, University of British Columbia, Vancouver, BC, Canada
*
Neuro-ophthalmology Section D, VGH Eye Care Center, 2550 Willow Street, Vancouver, BC, Canada, V5Z 3N9.
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Abstract

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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.

Résumé:

RÉSUMÉ:Contexte:

Selon les modèles cognitifs actuels, plusieurs processus sont impliqués dans la lecture et l'écriture.

Objectif:

Notre but était d'utiliser l'analyse linguistique pour clarifier la dysfonction cognitive sous-jacente à deux syndromes alexiques classiques.

Méthodes:

Nous rapportons quatre expériences effectuées chez deux patients, dont l'un présentait une alexie sans agraphie suite à des lésions occipitotemporales et l'autre une alexie avec agraphie suite à une lésion gyrale angulaire gauche.

Résultats:

Le patient porteur de lésions occipitales avait de la difficulté à distinguer de vraies lettres de simulacres de lettres et la lecture variait selon la longueur des mots, indépendamment de variables linguistiques comme la partie du discours, la fréquence des mots ou l'imageabilité. Il lisait des pseudo mots et il lisait mieux les mots dont l'épellation était régulière, ce qui indique que l'utilisation des règles de prononciation de graphème à phonème était préservée. À l'écriture on notait des erreurs qui témoignaient qu'il se fiait aux règles d'épellation de phonème à graphème. Par contre, le patient porteur l'une lésion gyrale angulaire gauche avait une meilleure reconnaissance des lettres et des mots ainsi que de leur signification. Sa lecture des mots dont l'imageabilité est élevée était meilleure, mais il faisait des erreurs de sémantique et était incapable d'utiliser les règles de graphème à phonème, témoignant d'une dylexie profonde. Son agraphie témoignait d'une altération de l'accès à un lexique interne et aux règles de phonème à graphème.

Conclusion:

Certains cas d'alexie pure peuvent être une agnosie de perception de la forme des mots avec perte de la représentation interne des lettres et des mots alors que le syndrome gyral angulaire d'alexie avec agraphie est une dyslexie profonde linguistique. La présence ou l'absence d'agraphie ne permet pas toujours de faire la distinction entre les deux. L'écriture peut refléter les déficits de lecture qui sont plus évidents et plus sévères chez les patients atteints du syndrome gyral angulaire.

Type
Research Article
Information
Canadian Journal of Neurological Sciences , Volume 35 , Issue 5 , November 2008 , pp. 616 - 624
Copyright
Copyright © The Canadian Journal of Neurological 2008

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