Development of selective verbal memory impairment secondary to a left thalamic infarct: a longitudinal case study.

A 68 year old man suffered an acute dysphasic episode with persistent memory disturbance while taking part as a control in a longitudinal magnetic resonance imaging (MRI) study. A small new left thalamic infarct involving the mamillo-thalamic tract could be demonstrated on volumetric MRI, coinciding with the development of a selective verbal memory impairment. This suggests that lateralisation of cognitive processing of visual and verbal material exists at the thalamic as well as the cortical level. High resolution volumetric MRI may be helpful in demonstrating small subcortical infarcts that may not be seen using computed tomography or conventional MRI.