[Dyslexia: actual status of our neurological and neuropsychological knowledge]

Developmental dyslexia is a neurological syndrome of unknown origin. Historical, conceptual, etiological, epidemiological aspects of developmental dyslexia are reviewed in a neuropsychological perspective. This article also reviews the known neuroanatomic, neuropathologic, and diagnostic basis of developmental dyslexia. Dislexic typology, with specific deficits in language, the visual domain or both, is discussed. Developmental dyslexia may be associated with several neuropsychological deficits. Its screening must be cognitively complete and according to accepted diagnostic criteria; a disorder manifested by difficulty in learning to read despite conventional instruction, adequate intelligence, and sociocultural opportunity.