Chapter 2 - Sensory abnormalites

Summary

The primary function of the sensory cortex is to discriminate sensation: appreciation and recognition of spatial relations, appreciation of similarity and differences of external objects, precise localization of the point touched, and identification of objects (stereognosis). Although less carefully examined than motor or speech abnormalities, somatosensory abnormality is present in at least half of stroke patients. The sensory abnormality is characterized by the presence of paresthesias and a selective loss of lemniscal sensation. Pontine tegmental strokes affecting the sensory tracts are often accompanied by sensory symptoms. Concomitant involvement of the adjacent pyramidal tract results in a sensory-motor stroke, and additional involvement of the cerebellothalamic fibers at the ventrolateral nucleus may produce a hypesthetic ataxic hemiparesis syndrome. Although motor symptoms are usually dominant in patients with subcortical strokes, small or even relatively large lesions primarily affecting the thalamocortical sensory radiation can result in pure or predominant sensory symptoms.