EBV or ZVZ… Which one to blame? A case of ADEM

Background: Acute Disseminated Encephalomyielitis (ADEM) is an immune-mediated demyelinating disorder which can occur following viral infections or vaccination and spontaneously. Several viruses can be implicated, including Epstein-Barr Virus (EBV) and Varicella Zoster Virus (VZV). Fever, headache, and meningeal irritation signs are the most common initial findings followed by seizures, focal neurological deficits and altered consciousness. Diagnosis is clinical and radiologic, being Magnetic Ressonance Imaging (MRI) the most important imaging exam. With appropriate treatment, prognosis is generally good.

Objective: To alert to less common etiologies and manifestations of ADEM

Methods: Report a clinical case of a child admitted to a suburban hospital in Portugal.

Clinical Report: 4-year old boy, admitted in the Pediatric Emergency Room (ER) with depression of consciousness and conjugate eye deviation to the right. In the previous 10 days, the family reported headache, frequent vomiting and fluctuant prostration, without fever. He also had recent history of chickenpox (20 days before admission). Blood analysis were unrevealing. Examination of cerebrospinal fluid (CSF) revealed pleocitosis (54 cells/mm3) with slight predominance of polymorphonuclear cells. He was hospitalized for investigation and started intravenous acyclovir. Cranioencephalic (CE) Computerized Tomography (CT) showed no alterations. Electroencephalogram documented diffuse slow-wave activity and CE-MRI revealed thalamic and subcortical lesions suggestive of ADEM. CSF microbiological culture was negative and multiplex Polimerase Chain Reaction for neurotropic virus was positive for EBV. Acyclovir was suspended at the 8^th day of hospitalization. He remained asymptomatic since the 6^th day after admission and was discharged after stopping acyclovir. He was posteriorly readmitted for immunoglobulin administration.

Conclusion: ADEM can be difficult to diagnose. Frequently, the etiologic agent remains unknown. In this case, EBV might be considered as an opportunistic agent in the setting of a transient immunosuppression state. We also highlight EBV as an important causative agent of ADEM.