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  • Updated 06.10.2024
  • Released 05.04.2001
  • Expires For CME 06.10.2027

Alexia without agraphia

Introduction

Overview

Alexia without agraphia (also known as “pure alexia” or “word blindness”) is an acquired disorder in which patients become unable to read but are still able to write. The deficit has been attributed to either a disconnection syndrome or a word form agnosia. This article reviews the clinical features, causes, and pathophysiologic arguments of this condition.

Key points

• Alexia without agraphia is believed to represent either a disconnection between language cortex and visual cortex or a word form visual agnosia.

• It occurs from lesions in the left occipitotemporal region and splenium of the corpus callosum.

• It is often accompanied by a right homonymous hemianopia.

• The differential diagnosis includes developmental dyslexia, visual disorders, aphasia, hemispatial neglect, and eye movement abnormalities.

Historical note and terminology

Alexia without agraphia (also called “pure alexia” and “word blindness”) refers to an impairment in reading with preservation of the ability to write. In its most severe form, it involves a complete inability to read. In its milder form, the patient can read but only by recognizing one letter at a time.

In 1892, Déjérine first described this entity in a man with associated incomplete right homonymous hemianopia from a lesion of the left fusiform and lingual gyri. He deduced that the left angular gyrus stored the visual representation of words needed for reading and writing and that disconnecting the visual inputs of both hemispheres from the left angular gyrus could disrupt reading but leave writing intact (33; 16). These conclusions were affirmed in 1965 by Geschwind, who introduced the concept of “cerebral disconnection” (42).

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