Disease course of Chronic Relapsing Inflammatory Optic Neuropathy (CRION) in a single care center

BACKGROUND: Chronic relapsing inflammatory optic neuropathy (CRION) is a recurrent, idiopathic optic neuritis and is considered as a rare disease. OBJECTIVE: To describe the clinical course during long-term follow-up of patients with a diagnosis of CRION. METHODS: From a cohort of 1,735 patients with demyelinating disorders, we selected patients aged over 16 years with CRION according to current criteria. Demographic and clinical data, including initial presentation, symptoms, number of relapses, time delay in diagnosis, diagnostic methods, and treatment were obtained from clinical files. Infections, autoimmune diseases, and multiple sclerosis, among other conditions, were ruled out in all patients. RESULTS: We analyzed 30 patients with CRION: 24 women and six men, with mean age of 42.8±10.2 years, median disease course of 7.9 years (5.29-13.1), and median number of attacks of 2 (IQR 2-4). The initial manifestation was ocular pain in 97% and bilateral and sequential affection in 87%. Visual acuity was recovered in 50%, did not improve in 33%, and recovered incompletely in 17%. Antibodies against aquaporin-4 (AQP4-Abs) were negative in 73.3%. Magnetic resonance imaging of the brain was normal in 76.7%. None of the patients evolved to another demyelinating disease over time. Initial treatment was methylprednisolone in 100%, and plasmapheresis in 20%. Currently, all patients are on maintenance treatment with mycophenolate mofetil or rituximab with a decrease in relapsing rate. CONCLUSIONS: Diagnosis of CRION is challenging and should be kept in mind. Prompt diagnosis, adequate treatment and close follow-up are essential to prevent disabling sequelae in these patients.