[Crossed Aphasia].

Crossed aphasia (CA) is a rare acquired language disorder caused by a right-sided brain lesion in dextrals. Based on a case report, relevant aspects for the diagnosis of CA and differential diagnoses will be outlined. Relevant hypotheses concerning etiology, epidemiology, phenomenology and pathophysiology will be discussed with reference to the literature. The phenomenon of CA has contributed for decades to the development of hypotheses concerning lateralization of cognitive abilities. © Georg Thieme Verlag KG Stuttgart · New York.