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Background: Hyperreflective retinal foci (HRF) visualized by optical coherence tomography (OCT) potentially represent clusters of microglia. We compared HRF frequencies and their association with retinal neurodegeneration between people with clinically isolated syndrome (pwCIS), multiple sclerosis (pwMS), aquaporin 4-IgG positive neuromyelitis optica spectrum disorder (pwNMOSD), and healthy controls (HC)-as well as between eyes with (ON + eyes) and without a history of optic neuritis (ON - eyes)., Methods: Cross-sectional data of pwCIS, pwMS, and pwNMOSD with previous ON and HC were acquired at Charité-Universitätsmedizin Berlin. HRF analysis was performed manually on the central macular OCT scan. Semi-manual OCT segmentation was performed to acquire the combined ganglion cell and inner plexiform layer (GCIPL), inner nuclear layer (INL), and peripapillary retinal nerve fiber layer (pRNFL) thickness. Group comparisons were performed by linear mixed models., Results: In total, 227 eyes from 88 patients (21 pwCIS, 32 pwMS, and 35 pwNMOSD) and 35 HCs were included. HRF in GCIPL and INL were more frequently detected in pwCIS, pwMS, and pwNMOSD than HCs (p < 0.001 for all comparisons) with pwCIS exhibiting the greatest numbers. ON + eyes of pwMS had less HRF in GCIPL than ON - eyes (p = 0.036), but no difference was seen in pwCIS and pwNMOSD. HRF GCIPL were correlated to GCIPL thickness in ON + eyes in pwMS (p = 0.040) and pwNMOSD (p = 0.031)., Conclusion: HRF occur in ON + eyes and ON - eyes across neuroinflammatory diseases. In pwMS and pwNMOSD, HRF frequency was positively associated with GCIPL thickness indicating that HRF formation might be dependent on retinal ganglion cells., (© 2025 The Author(s). European Journal of Neurology published by John Wiley & Sons Ltd on behalf of European Academy of Neurology.)

Background and Objectives: Susac syndrome (SuS) is a rare disorder characterized by encephalopathy, branch retinal artery occlusion, and sensorineural hearing loss, often accompanied by vertigo. Recent updates to diagnostic criteria and treatment guidelines have been made. This study examines clinical manifestations; disease activity; and risk factors of disability, dependency, and return to work in patients with SuS., Methods: A retrospective multicenter study was conducted on 20 consecutive patients with SuS with at least 2 years of follow-up. Clinical and paraclinical activities were assessed and rated according to the severity at onset and the end of follow-up. Cognitive function was assessed using the Montreal Cognitive Assessment while disability and dependence in daily activities were measured using the modified Rankin Scale. Employment status was graded., Results: The mean age at onset was 38.9 years, with a mean follow-up of 55.9 months. The female-to-male ratio was 1.86, and 45% of patients had the complete clinical triad. Severe cerebral involvement at onset was associated with a higher risk of cerebral exacerbations within the first year and with an increased long-term disability and dependency. Cognitive function improved in 75% of patients during follow-up. At disease onset, hearing loss excluding low frequencies occurred in 46.7%. Relapse of hearing loss was associated with greater impairment in daily activities. Male sex and elevated CSF protein levels were linked to poorer prognosis. Cerebral and inner ear exacerbations were most common in the first year while retinal exacerbations occurred more frequently, mainly within the first 2 years. Approximately 50% of patients resumed employment while 25% did not return to work., Discussion: Current treatment strategies for SuS do not fully prevent relapses. Severe brain manifestation at onset, male sex, and high CSF protein levels are risk factors of a worse prognosis of disability and dependence, indicating the need for intensive treatment. High-frequency hearing loss does not exclude SuS diagnosis.