Persisting childish behavior after bilateral thalamic infarcts.

We report a case with bilateral paramedian thalamic infarcts. The patient showed a dramatic personality change characterized by childish behavior and euphoria; which remained unchanged for 2 years after the onset. 'Vorbeireden' characterized by approximate answers was also observed. Anterograde amnesia had quite improved after 2 years, while retrograde amnesia for 1 year prior to the stroke onset and vertical gaze palsy remained unchanged. An MRI scan demonstrated bilateral medial thalamic and right midbrain infarcts without other lesions in the brain. A position emission tomography study showed that cerebral metabolic rate for glucose was markedly decreased in both thalami and in the cerebellum, and only slightly decreased in the parietal and occipital cortical regions. Cerebral metabolic rates of glucose in the frontal and temporal cortices were within normal range. The paramedian thalamic lesions per se may be responsible for the patient's personality change, 'Vorbeireden', and amnesia.