Why are some patients with severe neglect able to copy a cube? The significance of verbal intelligence

Cube-copying is often used to assess constructional ability of brain-damage d patients and the influence of unilateral spatial neglect is often pointed out in patients with right hemisphere lesions. However, some patients with severe neglect pel form cube copying satisfactorily. The aim of the presen t study is to identify the factors that affect the performance of cube-copy ing in patients with left unilateral spatial neglect. Constructional perfor mance was investigated in 100 patients with unilateral spatial neglect usin g a task to copy the Necker cube. The relationship of the patients' cube-co pying performance to the severity of their neglect, as well as other factor s (verbal intelligence, age, duration after onset of the disease, education al level, lesion site, piecemeal approach, and side of starting to copy) wa s analyzed. Twenty-two normal subjects also participated in this study as c ontrols. Among many factors adopted for analysis, neglect severity and verb al intelligence were found to be primary factors affecting the cube-copying performance of the patients with unilateral spatial neglect. The effect of neglect severity on cube-copying performance was apparent in the patients whose verbal intelligence was deteriorated, but was not observed in the pat ients with preserved verbal intelligence. Similarly, the effect of verbal i ntelligence on cube-copying performance was apparent in the:patients with s evere neglect, but not in the patients with mild neglect. We conclude that constructional ability in the copying of a cube is determined by verbal int elligence, as well as by the severity of unilateral spatial neglect. (C) 20 00 Elsevier Science Ltd. All rights reserved.