Discrepancy between dysmetric centrifugal movements and normometric centripetal movements in psychogenic ataxia

A method to unravel an aberrant motor behaviour in psychogenic ataxia is re ported. The kinematic features of fast reaching movements in the vertical p lane are described in a patient presenting a psychogenic ataxia. The proced ure compared centrifugal and centripetal movements. Path ratios were comput ed for each phase, as well as the ratios of the paths for centrifugal and c entripetal directions. Trajectories of centrifugal phases were erratic but centripetal movements were very regular, whereas both centripetal and centr ifugal movements were irregular in patients presenting an organic cerebella r syndrome. A similar incongruity between movements in opposite directions is also shown for a second patient exhibiting psychogenic ataxia. Discrepan cies between the centrifugal phase and the centripetal phase of multi-joint reaching movements support the diagnosis of a psychogenic movement disorde r. Copyright (C) 2001 S. Karger AG, Basel.