Clinical and dual-tasking aspects in frequent and infrequent fallers with progressive supranuclear palsy.

Progressive supranuclear palsy (PSP) is a rare neurodegenerative disease with no sufficient therapeutic options to date. Falls are the most devastating feature. The causes of these falls are not well understood. To test the impact of PSP-associated motor and cognitive features on falls, 26 PSP patients were prospectively recruited and divided into frequent fallers (> one fall/month, 18 patients) and infrequent fallers (<or= one fall/month, 8 patients). Further parameters were assessed by clinical investigation and biomechanical gait and balance analysis with and without dual-task paradigms. Physical activity was measured through an ambulatory device. Frequent fallers scored higher on the total PSP rating scale and the subscales "history," "mental," "bulbar," "supranuclear ocular motor," and "gait/midline exam" but not on disease duration, the subscale "limb exam," the UPDRS motor score and the sway analysis. Frequent fallers also showed an increased probability of an altered walking pattern with shortened step lengths and increased cadence under a dual-task situation. It is concluded that the occurrence of falls in PSP seems strongly associated with the deterioration of bulbar function, but not relevantly with typical parkinsonian features like rigidity and bradykinesia. The decreased ability to deal with distraction of attention under a dual-task situation points to a relevant impact of cortical and subcortical dysfunction on the frequency of falls.