Anterior callosal haemorrhage. A partial interhemispheric disconnection syndrome.

The interhemispheric disconnection syndrome secondary to a callosal haemorrhage is exceedingly uncommon. In the present study, 3 patients with haemorrhages restricted to the corpus callosum are presented. All 3 developed a partial anterior interhemispheric disconnection syndrome: unilateral tactile anomia, unilateral agraphia, unilateral apraxia, difficulty in copying drawings, dyscalculia as well as abnormalities of somaesthetic transfer and the 'alien hand' sign. The study of these cases allowed a close examination of the association between deficits in the transfer of specific neuropsychological information and the precise topography of callosal damage. Variability in the lateralization of cognitive functions, and possible mechanisms underlying the production of callosal haemorrhages after the rupture of saccular aneurysms are also discussed.