Allocentric and Egocentric Spatial Impairments in a Case of Topographical Disorientation

We describe a patient with a topographical disorientation after a stroke of the right mediotemporooccipital lobe including the parahippocampal cortex (PHC). Clinical observations and neuropsychological testing reveal an impairment of allocentric spatial representations as well as impairments of visuospatial learning and memory. These findings are in accordance with the well-known function of the PHC in topographical disorientation. As a new finding, results from oculomotor tasks show additional impairments of the egocentric spatial coordinate frame suggesting that in topographical disorientation due to a lesion of the right mediotemporooccipital lobe not only allocentric but also egocentric visuospatial functions are disturbed.