[A case of brainstem encephalitis associated with Epstein-Barr virus infection: differentiation of acute disseminated encephalomyelitis and Bickerstaff's brainstem encephalitis].

A 28-year-old woman initially suffered high fever and headache (day 1). Aseptic meningitis was diagnosed on day 3. Limb ataxia, however, appeared on day 7, and external ophthalmoplegia and drowsiness were recognized on day 8. Urinary disturbance and orthostatic hypotension appeared on day 13. Cerebrospinal fluid showed moderately high cell counts(mononuclear cells, 51/microliter; polynuclear cells, 9/microliter). MRI T2-weighted images showed high intensity lesions in the pons and mesencephalon. No serum anti-GQ1b IgG antibody was detected on day 4. Epstein-Barr virus (EBV) viral capsid antigen-IgG antibody was positive, and EBV determined nuclear antigen antibody was seroconverted. EBV-DNA was detected in the CSF by PCR. These findings indicate prior infection by EBV. After intravenous dexamethasone therapy, these symptoms rapidly disappeared. Our patient showed external ophthalmoplegia, ataxia, and disturbance of consciousness, which are the cardinal signs in Bickerstaff's brainstem encephalitis. The time course of her neurological symptoms, the presence of meningitis, and the MRI findings, however, indicated the pathogenesis of acute disseminated encephalomyelitis rather than Bickerstaff's brainstem encephalitis. We diagnosed this patient as a brainstem encephalitis associated with EBV infection.