The purpose of the examination of cortical sensation is mainly to see if there is evidence for a lesion involving the nondominant (usually the right) parietal cortex.

Cortical sensation does not need to be assessed routinely. Examination of cortical sensation may be helpful, however, in situations in which there is a question of whether a patient’s symptoms are due to a right hemisphere (cortical) process as opposed to a spinal cord or peripheral process. The finding of cortical sensory abnormalities in these situations, in the absence of significant gross loss to the primary sensory modalities, would be further evidence of a hemispheric (cortical) localization.

Cortical sensation refers to sensation that requires some processing by the cortex to discriminate one stimulus from another. The cortical sensory modalities (described in sections below) include graphesthesia, stereognosis, and the ability to perceive the presence of bilateral simultaneous sensory stimuli. These cortical sensory functions are in contrast to the primary sensory modalities (such as pinprick and vibration) for which there are specific peripheral receptors and that don’t require much further cortical integration.