Posterior callosal infarction. Clinicopathological correlations.

Clinicoanatomical observations on a patient with partial interhemispheric disconnection associated with complete ischaemic destruction of the splenium and of the posterior part of the body of the corpus callosum are presented. Neuropathological examination of the areas containing degenerated white matter indicated that the lesions affected the transcallosal fibres that link the cortex of the occipital lobes and the superior parietal lobules (SPL). The white matter situated in the temporal lobes was intact. This suggests that in man, and contrary to what has been described in the monkey, the callosal pathway followed by the temporal fibres is rostral to the one followed by the parietal or at least by the SPL fibres. The most prominent disconnection syndrome elements were left tactile anomia (in spite of a rather good tactile-motor integration between the hemispheres), left visual anomia, agraphia of the left hand and 'diagnostic' apraxia. The fact that the anterior part of the corpus callosum was intact accounts for the preservation of interhemispheric transfer of somatic sensory information and for the absence of left extinction during the dichotic listening test. An attempt is made to give a more detailed explanation of the results obtained during the different tests.