Allocentric visuospatial processing in patients with cerebral gliomas: a neurocognitive assessment.

Visuospatial function is a central neuropsychological domain which has been neglected in brain tumor studies. This study examined visuospatial function in 4 groups of brain tumor patients. The investigation involved 27 adult tumor subjects, 25 of whom had undergone resection and radiotherapy. Ten normal adults acted as controls. The 4 tumor groups were based on neuroanatomic locus - focal lesions were localized to clearly defined visuospatial areas in the left or right posterior parietal cortex or prefrontal cortex. Neuroanatomic and visuospatial assessment parameters were specified: only allocentric ('mental' or 'conceptual') operations were examined. A theoretical framework outlined the role of the posterior parietal and prefrontal cortices in allocentric spatial processing. Six visuospatial tests involving allocentric operations were applied to patients in whom tumors involved these cortical areas. In numerous analyses, the 4 tumor groups showed no significant differences with the control group on the allocentric tests. Between-group comparisons were also not significant. Analyses by gender revealed significant differences on shape rotation and line orientation tests, especially in the right hemisphere and parietal groups. Comparisons between focal radiation subgroups and 'nonradiation' subgroups produced unclear results. The main conclusions are that despite the presence of frontal or parietal tumors, (1) allocentric processing is hardly compromised, and (2) females show lower spatial performance than males due to tumor-related effects on a pre-existing pattern of cerebral lateralization. The study emphasizes the need to address visuospatial function in the neuropsychological study of brain tumor patients, particularly the role of intact spatial processing in this patient group.