ABSTRACT NUMBER: ESOC2026A555 VGLUT2-AUTOANTIBODIES-RELATED CEREBRAL VASCULITIS AND ENCEPHALITIS

Abstract Background and aims Antibodies against the vesicular glutamate transporter 2 (VGluT2) have recently been suggested to cause a new form of autoimmune disorder with predominant encephalitis, cognitive deficits and neuropathy. Only two cases of VGluT2-related encephalitis with cerebral vasculitis have so far been published [PMID: 40494504]. Methods Here, we describe the clinical manifestations and disease course of a patient with VGluT2-associated small vessel vasculitis. Results A 43-year-old woman presented with acute-onset auditory and visual hallucinations, memory impairment, confusion, gait instability, and ataxia. Her symptoms worsened progressively, and seizures emerged five months after onset. Workup showed encephalitis and cerebral small vessel vasculitis. Immunosuppressive therapy was then initiated, with high-dose methylprednisolone followed by long-term mycophenolate mofetil. In the following months, the symptoms gradually improved. At one year, the patient remained severely disabled, partial functional independence was regained by two years and improvement continued until 38 months. Twenty-one months after onset, the patient developed central artery occlusion in one eye. Serial brain magnetic resonance images revealed multiple inflammatory and ischemic lesions of varying ages across several vascular territories. There was no evidence of an embolic source or a prothrombotic disorder. Marked brain atrophy ensued. Cerebrospinal fluid analyses demonstrated early inflammatory and elevated neurofilament light chain levels, which improved but remained mildly increased at three years. VGluT2 autoantibodies persisted in serum with declining titers over time. Conclusions We describe the longitudinal clinical course of VGluT2-related encephalitis and cerebral vasculitis. VGluT2 antibodies should be analyzed in this clinical setting to detect this treatable disorder. Conflict of interest Andreea Ilinca: nothing to disclose