[CT perfusion abnormalities in a case of non-herpetic acute limbic encephalitis]

We report a 42-year-old woman of non-herpetic acute limbic encephalitis (NHALE) whose CT perfusion (CTP) images revealed abnormalities of the limbic system at the early stage. The patient had high fever, convulsion and memory disturbance soon after having caught a common cold, and was admitted to a hospital where she developed progressive disturbance of consciousness. She was then transferred to our hospital 7 days after the initial manifestations. Although enhanced CT images of the brain failed to find any lesion, CTP images revealed a focal increase in the cerebral blood flow and shortening of mean transit time in the bilateral hippocampi and amygdalae. MRI of the subsequent day showed high signal intensity lesions on diffusion, T2-weighted and FLAIR images at the same area. Her consciousness improved by intravenous administration of high-dose methylprednisolone together with other combination therapies. Her CTP images apparently improved by 5 weeks after the onset, but she was left with mild memory disturbance, amenorrhea secondary to hypothalamic failure, hyperosmia, and hypogeusia. In conclusion, CTP is sensitive enough to detect the lesions of the limbic system even in the early stage of NHALE.