Magnetic resonance imaging in a case of mumps postinfectious encephalitis with asymptomatic optic neuritis.

A 5-year-old male patient with asymptomatic optic neuritis and mumps postinfectious encephalitis or acute disseminated encephalomyelitis is reported. Magnetic resonance imaging (MRI) with a short inversion time inversion recovery sequence was valuable in detecting clinically silent lesions of the unilateral right optic nerve in addition to visual evoked potentials. Evidence of concurrent optic neuritis was useful for detecting more extensive neurological involvement, leading to the diagnosis of mumps postinfectious encephalitis. A systematic MRI study should be performed in children with mumps encephalitis, regardless of appreciable clinical deficits.