Walsh & Hoyt: Pure Alexia (Word Blindness, Alexia Without Agraphia)

The key feature of pure alexia is a dramatic dissociation between the ability to read and normal writing performance: such patients can write fluently and spontaneously, but having done so cannot read what they have just written. The severity of this defect can vary. At the severe end, patients with global alexia cannot read numbers, letters, and other abstract symbols, such as musical notation for pitch, road signs, and map symbols, let alone words. At the mild end, patients have slow reading with occasional errors, diagnosable only by comparison with controls of similar educational level. These patients decipher words one letter at a time (letter-by-letter reading, or spelling dyslexia). The characteristic sign is the word-length effect, in that the time needed to read a word increases with the number of letters in the word. Signs and symptoms. Covert reading. Anatomy, pathology, and mechanisms of pure alexia,