A case of acute encephalopathy presenting with transient functional disability in various new tasks and hypoperfusion of the right frontal and temporal lobes on SPECT.

We report the case of a 5-year-old boy with acute encephalopathy presenting with transient executive dysfunction such as functional disability in various new tasks and hypoperfusion of the right frontal and temporal lobes on single photon emission tomography (SPECT). He presented with a 2-day history of disturbed consciousness, and electroencephalography in an awaked state showed diffuse high-voltage slow waves. Although MRI did not show any abnormality 3 days after initial onset of illness, SPECT showed hypoperfusion of the right frontal and temporal lobes at the same time. At 20 days after onset, the Kaufman assessment battery for children (K-ABC) test showed that sequential processing scale scores were significantly lower than simultaneous processing scale and achievement scale scores. He showed transient executive dysfunction such as functional disability in various new tasks at the same time. Abnormal brain perfusion on SPECT was improved at 8 months after onset and the sequential processing scale of K-ABC was likewise improved at 12 months after onset. These findings suggest that SPECT is helpful for diagnosing pathophysiological mechanisms with acute encephalopathy, and the combination of neuropsychological examination and SPECT study is useful for evaluating higher brain dysfunctions such as executive dysfunction.