Marchiafava-Bignami disease, syndrome of interhemispheric disconnection, and right-handed agraphia in a left-hander.

We present an original case of Marchiafava-Bignami disease in a 47-year-old left-handed alcoholic man. Computed tomography and magnetic resonance imaging demonstrated the typical lesion, a necrosis of the middle portion of the corpus callosum. Diagnosis may thus be established in the living. In our case, the course was not fatal, which, to our knowledge, has only been described in four other cases in the literature. Clinically, our patient demonstrated an interhemispheric disconnection syndrome. The striking feature is that some of the symptoms were on the side opposite of the one that has previously been described in the literature, eg, right-handed agraphia, while others were on the usual side, eg, left-handed anomia. We discuss cerebral dominance for speech and handedness in left-handers and come to the conclusion that our patient's clinical features can only be explained by right hemispheric dominance for handedness and bilateral hemispheric representation of speech.