Clinical scales exist to measure the severity of cerebellar ataxia. However, there are no clinical scales that diagnose cerebellar ataxia and differentiate it sensorimotor characteristics from other impairments. The long term goal of this work is to develop a clinical scale that will discriminate ataxic from non-ataxic motor signs. In this multi-site project, our lab is testing whether specific reaching deficits expected in ataxia patients are also observed in patients with cerebral stroke who have paresis, somatosensory loss, and/or spasticity. We hypothesized that dysmetria, but never hypermetria, and kinetic tremor, but never intention tremor, would be present in patients with cerebral stroke but intact cerebellar function. Subjects with ischemic stroke (n=3) and healthy control subjects (n=3) were instructed to reach as quickly and as accurately as possible to a target under various conditions, including eyes open, eyes closed, to a remembered target, and tracking a target. A motion capture system recorded arm movements in three dimensions. We found that stroke subjects often showed decreased endpoint accuracy (dysmetria), abnormal arm oscillations (tremor), slowness, and increased variability, however none demonstrated significant hypermetria or intention tremor, compared to controls. These preliminary findings support our hypothesis that hypermetria and intention tremor may be important features of cerebellar ataxia that would reliably distinguish it. Other labs will test this same hypothesis with different neurological patient populations. In the future, the scale under development here will be helpful to accurately establish the degree to which ataxia is a key component of a child’s movement disorder. "