Incomplete split-brain syndrome in a patient with chronic Marchiafava-Bignami disease.

A 40-year-old male patient is presented who survived Marchiafava-Bignami disease and recovered sufficiently to be assessed neurologically and neuropsychologically in some detail. Besides dementia, lack of initiative, and psychomotor retardation here ascribed to extracallosal damage, he showed a number of symptoms of hemispheric disconnection such as left-sided apraxia, poor bimanual coordination in specific laboratory tests, and deficits in the interhemispheric transfer of somaesthetic information. Other commissural functions, such as interhemispheric transfer of tactile, visual and auditory information as well as bilateral coordination in previously overlearned tasks, were nearly intact. The observed dysarthria could be meaningfully discussed in relationship to postcallosotomy mutism. It is concluded, that the partial interhemispheric disconnection syndrome in Marchiafava-Bignami disease lacks functional compensation which is different from the usual course in partial commissural section.