[Case of defective route finding following right anterior thalamic infarction]

Defective route finding is a symptom in which an indivisual demonstrates inhibility to find the way in the familiar places. This symptom arises from lesions at the right parieto-occipital region and the right posterior part of the splenium of the corpus callosum. We present a case of defective route finding resulting from the right anterior thalamic infarction. A 63-year-old right-handed man abruptly presented with difficulty in route finding on his way home. Neither spatial neglect nor agnosia was observed with pictures of his house and surrounding streets. Although there was an attention disturbance, his activities of daily living were spared. Brain MRI revealed a fresh infarction at the right anterior nucleus of the thalamus. Single photon emission computed tomography using 123I-methyltyrosine showed hypoperfusion at the right parieto-occipital region as well as the right thalamus. Neuropsychological tests showed visuospatial memory disturbance. To our knowledge, this is the first report of defective route finding caused by the right anterior thalamic infarction. The right anterior thalamic nucleus might be involved in the visuospatial recognition circuit.