Bilateral thalamic encephalitis due to Epstein–Barr virus in an elderly patient: a case report and literature review

Bilateral thalamic encephalitis due to Epstein-Barr virus (EBV) is a rare and severe manifestation of EBV infection, often leading to rapid neurological deterioration and poor outcomes. We report the case of an 82-year-old man with a history of arterial hypertension and a previous herpes zoster infection who presented to the emergency department with high fever and acute neurological impairment evolving into coma (Glasgow Coma Scale, GCS 3). Cerebrospinal fluid (CSF) analysis revealed mild lymphocytic pleocytosis, elevated protein and normal glucose. EBV-DNA was detected by polymerase chain reaction (PCR) and serology confirmed positive anti-EBV IgM antibodies. Autoimmune and paraneoplastic panels, including anti-NMDA receptor, anti-GQ1b, anti-MOG, anti-AQP4 and anti-LGI1 antibodies, were negative. Magnetic resonance imaging (MRI) demonstrated bilateral thalamic hyperintensities on T2-weighted and FLAIR sequences, with restricted diffusion on DWI and corresponding hypointensity on ADC maps, without contrast enhancement. Angiography showed normal patency of the main intracranial vessels. Differential diagnoses such as autoimmune encephalitis, acute disseminated encephalomyelitis, Bickerstaff's brainstem encephalitis, vascular, metabolic and other viral causes were excluded. Despite prompt antiviral and corticosteroid therapy and intensive supportive management, the clinical outcome was poor. A comprehensive literature review was performed, highlighting key clinical and radiological findings from previously published cases of EBV-related bilateral thalamic encephalitis, to improve recognition and understanding of this rare and devastating condition.