Cortical Control of Vertical Versus Horizontal Saccades in Parkinsonian Syndromes

Examination of saccades has gained overwhelming acceptance as a clinical tool in evaluation of parkinsonian syndromes. While Parkinson's disease patients usually evidence hypometric self-paced saccades, patients with progressive supranuclear palsy characteristically show small and slow saccades, especially in the vertical direction. Although the brainstem structures responsible for the control of saccades have been thoroughly studied, the cortical saccadic circuitry, particularly for vertical saccades is far less known. We sought to compare functional Magnetic Resonance Imaging (fMRI) activation between two parkinsonian syndromes during the execution of vertical and horizontal saccades.