We report a 61-year-old right-handed man developing disturbance of memory after a discrete thalamic infarction. Neuropsychological assessment revealed deficits in memory with retrograde and anterograde components, especially for verbal material. Brain MRI showed a left anterior thalamic infarction with normal angiographic findings. Despite the small lesion in the thalamus, he showed prolonged memory disturbance and a Brain SPECT image revealed decreased uptake in the ipsilateral fronto-temporo-parietal cortex and contralateral cerebellum. This diaschisis, a phenomenon caused by disconnection of the neural pathway helped us to evaluate the functional state of the patient and this imaging technique was valuable for obtaining to get more information for the evaluation of the neurological state and neuronal connections. In conclusion our findings correspond well with the understanding of amnesia as a disconnection syndrome because of the evidence of diaschisis on the Brain SPECT image.
Amnesia/*etiology ; Brain/*radionuclide imaging ; Case Report ; Cerebellum/radionuclide imaging ; Cerebral Infarction/*complications/radionuclide imaging ; Human ; Male ; Middle Age ; Thalamic Diseases/*complications/radionuclide imaging ; *Tomography, Emission-Computed, Single-Photon

The six patients included in this study had painful dysesthesia, resulting from vascular lesions in or near the thalamus, confirmed by computerized tomography(CT) brain scan. Using hexamethyl propyleneamine oxime(HM-PAO) single photon emission computed tomography(SPECT) brain scanning, regional cerebral perfusion(rCP) was demonstrated. In contrast to three patients with lesions near the thalamus who showed symmetrical cortical radioactivity, the other three patients with thalamic lesions revealed decreased rCP in the ipsilateral cerebral cortex on HM-PAO brain SPECT. We thought that the loss of afferent activating stimuli from the thalamus led to decreased cortical neuronal activity and the following hypoperfusion. In patients with thalamic syndrome resulting from thalamic lesions, the role of the remote effect of the thalamic damage and consequent cortical deregulation in the development of thalamic pain and/or neuropsychological symptoms cannot be excluded completely.
Brain/*radionuclide imaging ; Female ; Human ; Male ; Middle Age ; Organotechnetium Compounds ; Oximes ; Pain/etiology ; Syndrome ; Technetium/diagnostic use ; Technetium Tc 99m Exametazime ; Thalamic Diseases/*radionuclide imaging ; Tomography, Emission-Computed, Single-Photon