Cerebellar allocentric and action-intentional spatial neglect.

Contralesional hemispatial neglect most often results from lesions in the right posterior temporoparietal cortex. Less commonly, contralesional and ipsilesional neglect are caused by lesions in the frontal lobe. Although unilateral left cerebellar lesions have been reported to cause body-centered (egocentric) ipsilesional neglect, they have not been reported to cause left-side object-centered (allocentric) neglect together with a leftward action-intentional bias. We describe a patient who had these signs of neglect 7 months after a left cerebellar hemorrhage. This 61-year-old right-handed woman reported emotional lability and difficulty walking, frequently bumping into things on her left side. Neurologic examination revealed ocular dysmetria and left-side limb ataxia. Neuropsychological tests showed evidence of neglect. On a clock-drawing test, the patient accurately drew a circle but her number placement deviated to the left side. She showed the same leftward deviation when she tried to draw a circle composed of small triangles. Although her line bisection was normal, on an allocentric task of open-triangle cancellation she was most likely to neglect triangles with a left-side opening. Her performance on this task indicated left allocentric neglect. Her leftward deviation on the clock and figure drawing tasks seems to be a form of an action-intentional grasp, which may have been induced by right frontal dysfunction superimposed on a deficit of global attention.