Assessing Mental Imagery to Evaluate Topographical Disorientation: Group Study and Preliminary Normative Data.

There is currently no specific neuropsychological test assessing spatial orientation abilities, despite the fact that navigational deficits are heavily incapacitating in daily life. This lack of a specific test is probably due to theoretical vagueness of concepts in this field and important interindividual differences in spatial cognition. Here we propose a new standardized test assessing a fundamental component of spatial orientation-namely, mental imagery: Adequate mental visualization of the environment is indeed a necessary step in finding one's way. Two conditions of mental imagery were proposed to a group of 58 patients with a right cerebral lesion and to a control group (N = 117). The 1st condition assessed global, categorical imagery; the 2nd evaluated precise, metric imagery. We evaluated performance of the 2 groups in the 2 conditions and the impact of sociodemographic variables (age, gender, education). Results show that the right-lesioned patients presented difficulties in mental imagery, especially in the metric condition. Moreover, the data indicate a global impact of age and a milder effect of education on mental imagery abilities. Although sample sizes are sometimes small, preliminary normative data are given; already in the present form, they are usable and informative in assessing mental imagery, and more generally, spatial orientation, in a clinical practice.

Assessment of Topographical Disorientation: First Application of New Tests and Case Report.

A right posterior cerebral lesion can lead to an inability to orient and can consequently interfere with daily-life autonomy. Despite the wide literature about navigation abilities, it is still difficult to assess topographical disorientation (TD) because of the interindividual specificity of spatial knowledge and the diversity of symptoms. We describe here a set of new tests evaluating spatial cognition in a patient with TD presenting difficulties in navigating inside the hospital and in his hometown more than 3 years after his diffuse ischemic right Sylvian stroke. These tests assess mental imagery (global and specifically spatial imagery), perspective change, and the ability to recall spatial relations in familiar environments. The evaluation revealed difficulties with all the tests (but not in global mental imagery) in this patient when compared with matched controls. Hence, these new tests seem specific and affected by a right hemispheric lesion. The observed deficits can explain, at least partially, the spatial orientation difficulties experienced by this patient in the hospital and familiar environments. In conclusion, these tests could be appropriate tools for the assessment of visuospatial and spatial processes.