Visual event-related potentials in patients with spinocerebellar degeneration

Background. Cognitive disorders have been known to exist in patients with spinocerebellar degeneration. The aims of this study were to evaluate Visual event-related potentials (ERPs) in spinocerebellar degeneration and to determine the correlations between ERP findings and quantitative MRI parameters. Methods. The subjects consisted of sporadic olivo-ponto-cerebellar atrophy (OPCA; six cases), striatonigral degeneration (SND; five cases), sporadic late cortical cerebellar atrophy (LCCA; three cases) and familial cortical cerebellar atrophy (familial CCA; three cases). Visual ERPs were recorded using oddball and S1-S2 paradigms. We measured several quantitative MRI ratios, regarding midsagittal MRI view of the posterior fossa. Results. Well-formed P300 peaks were recognized in all patients with LCCA, SND and familial CCA. Among six patients with OPCA, three patients presented with prominent extrapyramidal motor deficits, besides cerebellar ataxia showed poorly formed P300. The other three patients showed normal P300. P300 amplitude and MRI ratios of the ventral pens and lower vermis areas showed significant correlation in patients with OPCA and SND. Conclusion. Our observation of normal P300 in cases of severe cerebellar atrophy indicates that cerebellum itself has little involvement in P300 generation. Correlation between ERP and MRI ratios suggests that ERP responses tend to decline with progression of illness or with pathological severity.