Impairments in premorbid knowledge recall in patients with hemispheric and intraventricular brain damage.

A total of 104 patients with hemispheric arteriovenous malformations (AVM; in the frontal, parietal, and temporal lobes), along with 21 patients with craniopharyngiomas and 21 patients with aresorptive hydrocephalus, were studied. Impairments of the recall of knowledge acquired before disease onset were found in 12 patients with hemispheric AVM. All had suffered severe intraventricular hemorrhage. Similar memory defects were noted in three patients with craniopharyngiomas and 12 with hydrocephalus. These patients had lesions of the mediobasal (periventricular) parts of the brain (frontal and parietal lobes), predominantly of the right hemisphere, as well as the diencephalic regions. The syndrome of selective retrograde amnesia in lesions of these structures was characterized by impairment of the recall of dates and, less frequently, details of event content and autobiography. It is emphasized that processes of recall of the sequence and selectivity of traces during actualization of "old" knowledge played the greater role in the mechanism of development of these impairments. The possible roles of the right and left hemispheres, as well as the diencephalic area, in the information encoding and decoding are discussed.