[The mechanism of unilateral spatial neglect]

We investigated a test for unilateral spatial neglect and discussed the mechanism of this symptom. Seventy eight patients with lesions on the right cerebral hemisphere were examined on line bisection, line cancellation, figure copying, clock drawing and location on the map. The statistical analysis revealed (1) there were no correlations between line bisection and clock drawing or between line bisection and location; (2) those with abnormal results on line bisection were apt to indicate normal results on line cancellation and figure copying, while in line cancellation, figure copying, clock drawing and location, normal results on one task meant normal results on the other. These results indicated clock drawing and location might include different factors from other tasks, line bisection was the most sensitive task for unilateral spatial neglect, and abnormality on line cancellation might be similar to that figure copying. Unilateral spatial neglect may be based on several disorders, and it may be assumed to have several aspects. One of these disorders may be defective searching. Unilateral spatial neglect may be more severe when there is sensory disturbance (hemianopsia) with a searching deficit. Other disorders, such as cognitive disturbance, memory disturbance and so on, may also be associated with unilateral spatial neglect, and it is necessary to consider the versatility of this symptom.