Utilization behavior after right thalamic infarction.

We report a patient who showed exaggerated responses to external cues (utilization behavior), motor impersistence, and a right-hand-predominant instinctive grasp reaction after right thalamic infarction. High-resolution computed tomography with stereotaxic lesion localization revealed almost complete destruction of the ventroanterior nucleus and intralaminar nuclei of the right thalamus; the dorsomedial nucleus was only partially involved. Single photon emission computed tomography revealed hypoperfusion in the right thalamus and over the entire right cerebral cortex with some prominence in the frontal area. From these observations, we believe that the utilization behavior in our case was caused by the disturbance in maintaining cortical tone of the right hemisphere as well as by the dysfunction of the right frontal lobe, both secondary to the damage to the right ventroanterior nucleus and intralaminar nuclei.