LAUSR

BACKGROUND Susac syndrome (SuS) is an rare occlusive micro vessel disease of the brain, retina, and inner ear. We aimed to determine whether brain lesion load at the acute phase predict poor outcomes in SuS. METHODS A prospective national cohort study was conducted from December 2012 to December 2019 in 20 centres in France. Patients included at the principal investigator's center with available brain MRI at diagnosis were analyzed. MRI was reviewed by an experienced neuroradiologist blinded to clinical status. The size, topography and number of diffusion-weighted imaging-hypersignals (DWI-HL) were analyzed at diagnosis and during follow up. Outcomes involved descriptive characteristics of patients at onset and last follow up. RESULTS Twenty-three patients (38.1 [18.8-56.5] years, 16 females) were prospectively studied. The triad (i.e. brain, eye and ear involvement) was complete at onset in 17. Brain MRI was performed 1.1 [0.1-3.4] months after the first symptom. All patients had DWI-HL at the acute phase. Patients were separated in 2 groups according to the number of DWI-HL on first MRI: a first group of patients (n=15) displaying low brain lesion load (<50 DWI-HL per patient) and a second group of patients (n=8) displaying high brain lesion load (≥100 DWI-HL). The median follow-up was 57.9 [9.7-98] months. Clinical features, treatment, relapses rate, time to disappearance of DWI-HL, disabilities, and professional outcome did not differ according to brain lesion load. CONCLUSIONS Brain lesion load assessed by DWI at the acute phase is not associated with risks of disability in SuS.