No abstract

We administered a large battery of neuropsychological tests to an heterogeneous cohort of genetically defined spinocerebellar ataxia (SCA) patients in order to assess their cognitive profile and to compare cognitive impairment among different SCA genotypes, particularly between SCA with the classical pattern of olivo-ponto-cerebellar atrophy (SCA1 and SCA2) and those with a relatively "pure" olivo-cerebellar atrophy (SCA6 and SCA8). Our data revealed a neuropsychological picture characterized by fronto-parietal involvement with mnestic, linguistic, visuospatial, attentional, executive, and mood changes, in agreement with the cerebellar cognitive affective syndrome definition. We found a homogeneous neuropsychological profile among SCA subgroups with a prominent role of frontal dysfunction--particularly, attention, memory, and executive functions. We analyzed the possible interactions between neuropsychological pattern and clinical, demographical, and genetic variables. We found the presence of a cognitive impairment at the early stages of the disease, without visuospatial alterations, which appeared later. Age and education represented the most important demographic factors to predict the neuropsychological performance in SCA and in controls, but their effect in patients had definitely more impact. In our sample education could represent a protective factor and a marker of an enriched environment or a better developmental cognitive differentiation. We demonstrated that in our patients there was a distinct subgroup of high functional subjects and that triplet repeats modulated the effect of aging on cognition and progression of motor disability.

Cerebellar agenesis is a rare disorder. We present the neurological and neuropsychological features of a patient with partial cerebellar agenesis (TZ), together with SPECT perfusion and fMRI activation during a finger tapping task. TZ shows only mild cerebellar signs, while neuropsychological testing discloses severe deficits in many domains, in accordance with the theorized role of the cerebellum in cognition. FMRI and SPECT demonstrate an activation and a symmetrical perfusion of the cerebellar remnants, that can be related to the residual cerebellar motor function. The left frontal and parieto-temporal cortex hypoperfusion can explain the severe cognitive impairment and could be linked to the abnormal cerebellar development.

Our results replicate previous fMRI results demonstrating reproducible motor-related brain activations and extend the field to a complex cognitive task, thus providing evidence of the safety for routine clinical use of 1-T equipment.