Sequential MRI, SPECT and PET in respiratory syncytial virus encephalitis

We report on a 3-year-old girl with respiratory syncytial virus (RSV) encep halitis manifested by disturbance of consciousness, conjugate eye deviation , anuria, truncal ataxia and intention tremor. T2-weighted magnetic resonan ce imaging (MRI) showed hyperintense areas in the cerebellar cortex. No les ion was detected in the cerebral cortex, pens or spinal cord. The hyperinte nse areas in the cerebellar cortex diminished with recovery from the clinic al manifestations and had resolved 2 months after onset. The MRI lesions in the cerebellum were considered to be due to oedema. SPECT and positron emi ssion tomography (PET), performed 3 months after onset, disclosed areas of hypoperfusion and hypometabolism at the same sites. One year after onset, M RI showed mild atrophy of the cerebellum. Hypoperfusion on SPECT and hypome tabolism on PET remained. Neuroimaging showed that ataxia and tremor in thi s case were the result of cerebellitis, The patient has no neurological def icit except for mild truncal ataxia. This patient is a rare example of RSV encephalitis.