More Falls in Cerebellar Ataxia When Standing on a Slow Up-Moving Tilt of the Support Surface.
We investigated how subjects with cerebellar ataxia (CA) adapt their postural stability and alignment to a slow and small tilt of the support surface allowing for online postural corrections. Eight subjects with CA and eight age- and gender-matched healthy control subjects participated in the study. Subjects stood eyes closed for 1 min after which the support surface was tilted 5° toes-up at a ramp velocity of 1°/s. The toes-up position was held for 2.5 min after which the surface rotated back down to level with identical tilt characteristics. As reflected by the large number of falls, subjects with CA had marked difficulty adapting their posture to the up-moving incline in contrast to control subjects. Subjects with CA who lost their balance had faster trunk velocity and excessive backward trunk reorientation beginning within the first second after onset of the tilting surface. In contrast, the down-moving tilt to level did not result in instability in CA subjects. These results suggest that instability and falls associated with CA derive from an inability to maintain trunk orientation to vertical while standing on a slow-moving or unstable surface. This study underscores the importance of the cerebellum in the online sensory control of the upper body orientation during small amplitude and slow velocity movements of the support surface.
['Paquette|Caroline|C|', 'Franzén|Erika|E|', 'Horak|Fay B|FB|']
D000058:Accidental Falls D000368:Aged D001696:Biomechanical Phenomena D002524:Cerebellar Ataxia D005260:Female D006801:Humans D007866:Leg D008297:Male D008875:Middle Aged D004856:Postural Balance D011187:Posture D060726:Torso
Accidental fall Motor activities Movement disorders Postural balance Torso