Cognitive dysfunction following thalamic stroke: a study of 16 cases and review of the literature.

The thalamus is a relay center for afferent sensory pathways that regulates and transmits peripheral stimulation to various representative areas of the cortex. Aphasia, neglect and anosognosia were also reported to occur after thalamic lesions, in the absence of cortical pathology. However, considerable controversy exists as to the pathogenetic mechanisms, and incidence of cognitive abnormalities following thalamic lesions. We present a series of sixteen consecutive stroke patients with thalamic stroke (n=12) or hemorrhage (n=4), admitted to a university based neurology department. Dysphasia was observed in seven of eight patients with left thalamic strokes (five in the territory of the tuberothalamic artery, two inferior-lateral thalamic lesions and one in the area supplied by the anterior choroidal artery). Neglect and anosognosia appeared in five of eight patients with right side thalamic insults (two each in the territories of the tuberothalamic and thalamogeniculate arteries and one in the area supplied by the posterior choroidal artery). These findings reconfirm those found in previous studies and suggest that the thalamus is part of an integral neuronal network concerned with cognitive functions.