Astasia-abasia is the name that has sometimes been given to a disorder of gait characterized by impaired balance (disequilibrium), wide base, shortened stride, start/turn hesitation, and freezing. The term has no standardized definition and hence may mean different things to different observers. It has also been used to describe a disorder characterized by inability to stand or walk despite normal leg strength when lying or sitting, believed to be psychogenic (although gait apraxia may have similar features). Modern clinical classifications of gait disorders subsume astasia-abasia under the categories of subcortical disequilibrium and frontal disequilibrium (i.e., gait disorders with prominent disequilibrium or impaired postural control). A transient inability to sit or stand despite normal limb strength may be seen after an acute thalamic lesion (thalamic astasia).
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