Role of visuospatial cognition assessment in the diagnosis and research of atypical parkinsonian disorders

Visuospatial abilities play a pivotal role in our daily living. Indeed, our survival depends, to a great extent, on our ability to navigate sensory space. This means our ability to use spatial maps dependent on visual, tactile, and auditory information to form and guide motor programs. Visuospatial abilities are complex brain operations requiring integration of occipital, parietal, and frontal lobe function, as well as the contribution of subcortical structures. Consequently, it is not surprising that visuospatial skills are often impaired in diseases with movement disorders—an impairment that depends both on the type and on the stage of the disease in question. Investigating visuospatial skills is helpful not only for differentiating among various diseases with movement disorders, but also for analyzing the source of patients’ everyday life impairment, as this can, in turn, generate useful pointers for the development of remedial strategies. Also, in the detailed analysis of visuospatial performance in patients with movement disorders,particular care must be taken to separate motor from cognitive components. In the devising of neuropsychological tools that can help us to gain a new insight into cortical and subcortical contributions to these activities, this represents a constant challenge. The aim of this chapter is to review the contribution of visuospatial assessment in the differential diagnosis of movement disorders. After presenting a classification of visuospatial skills, we discuss the evidence of visuospatial dysfunction in Parkinson’s disease (PD) and in the various atypical parkinsonian disorders. We then advance our own proposal for visuospatial assessment in this group of patients.