Cognitive impairments in cerebellar infarcts.

The effects of the cerebellum on cognitive functions (CF) are poorly known and inadequately studied. Neurological, neuropsychological, and neuroimaging studies were performed on 25 non-random patients (14 female, 11 male, mean age 51.8 +/- 18.0 years) with isolated cerebellar infarcts. Cognitive impairments (CI) were seen in 22 patients (88%). These included impairments of attention, planning, control, abstract thought, memory, and speech disturbances (naming difficulties, irregularity of speech, agrammatism, dysprosodia), visuospatial and quasispatial disturbances, and counting impairments, demonstrating dysfunction of the anterior and posterior associative areas of the cortex. The extent of CI varied: 16 patients (64%) showed impairments only in neuropsychological tests, while six (24%) had clinically apparent impairments. Clinically significant CI developed in lesions of particular areas (posteroinferolateral and posteromedial/median) of the cerebellar cortex associated with the dominant hemisphere of the brain. The existence of clinically significant CI was independent of infarct size: infarcts were smaller (mean 5.65 cm3) in patients with marked impairments than in others (mean 12.8 cm3). The typical signs of cerebellar infarcts (ataxia, vertigo, vomiting) were seen in all patients with clinically insignificant and in only two of six patients with clinically significant CI. The present studies demonstrated the involvement of the cerebellum in the modulation of CF. The extent of CI in cerebellar infarcts depended on infarct location. The topical localizations of cerebellar zones controlling CF and movement are different.