13. Parieto-occipital mapping-demonstrative cases

Abstract

In this presentation, I will give an overview of how we can map different eloquent regions of parietal and occipital lobes. I will start with the anatomy with different cytoarchitecture and thus different functions of distinctive regions of these lobes. I will then present several neurophysiologic techniques that can be used for functional mapping, such as somatosensory evoked potentials (SSEPs) for intraoperative mapping and monitoring somatosensory cortex, visual evoked potentials (VEPs) for mapping striate cortex, direct electrical cortical stimulation for positive and negative cortical mapping. I will present specific tasks to be used during awake craniotomies for mapping of parietal functions. I will also present a case of visual mapping using VEPs and electrical stimulation in a case of intractable lesional epilepsy (from a parieto-occipital stroke). I will conclude with a case of mapping the sensorimotor cortex using exclusively median SSEPs recorded via a multicontact subdural grid electrode and in the absence of visual cortical inspection, in a patient with intractable lesional epilepsy from an extensive neurodevelopmental lesion in the pericentral regions.