Thalamic stroke

Abstract

Thalamus has been labeled as the "Grand Central Station" of the brain because virtually all incoming information travels through it before reaching the cerebral cortex and all areas of the cortex project to the thalamus. Compared to the uncommon non-vascular insults like Korsakoff's syndrome due to the thiamine deficiency, vascular insultsconstitute the commonest source of injury to the thalamus. Thalamus is predominantly supplied by multiple small vessels originating from the posterior cerebral and communicating arteries, with significant variations and overlap. The stroke syndromes are not specific to individual nuclei because most vascular lesions are fairly large that result in a great deal of overlap of symptoms due to infarction or hemorrhage from a particular artery. The structure-function relationship is too complex and the information about the functional anatomy of thalamus has been largely derived from patients evaluated after thalamotomy and insertion of thalamic stimulation devices. Recent advances in functional imaging with magnetic resonance imaging and sophisticated use of diaschisis for analyzing the corticothalamic connectivity have significantly improved our understanding. In general, injury to the left side may be associated with language deficits in language, verbal intellect and verbal memory while a right-sided injury results in visuospatial deficits and impaired nonverbal intellect. Bilateral injury is associated with severe memory impairment. Other deficits due to the thalamic injuries include confusion, delirium, visual hallucinations, peduncular hallucinosis and cognitive deficits. We discuss functional areas of thalamus, their vascular supply and clcinical presentations due to various acute ischemic and hemorrhagic lesions. © 2011 Nova Science Publishers, Inc. All rights reserved.