Cognitive functions are related to our ability to build an internal representation of the world, the conceptual representation system, based on a large-scale neuronal network. This system is connected with more circumscribed and lateralized operational systems that allow us to translate thoughts into words (spoken, written or gestures), images, numbers or other symbols, to store and retrieve information when necessary and to make decisions or act upon them. Most of these operational abilities are subserved by distributed networks with areas of regional specialization, organized according to their specific processing capacities.
The pattern of cognitive/behavioral impairment observed after ischemic stroke is relatively stereotyped, since it follows the distribution of the vascular territories. However, in the hyperacute stage symptoms are likely to be amplified by additional regions of ischemic penumbra, mass effects and diaschisis (impairment of intact regions that are functionally connected with the damaged area), and, in the chronic stage, functional reorganization and brain plasticity mechanisms make neuroanatomical correlations loose and less predictable.
In hemorrhagic lesions, vasculitis, and cerebral venous thrombosis the pattern of cognitive defects is less stereotyped due to the variability of lesion localization, size and number, or particular pathogenic mechanisms that may cause diffuse impairment.
In this chapter we will present the most common cognitive and neurobehavioral deficits secondary to stroke, according to symptom presentation.
Language disorders, or aphasia, occur following perisylvian lesions (middle cerebral artery territory) of the left hemisphere and have a marked impact on the individual quality of life, autonomy and the ability to return to work or previous activities.