The Forgotten Tract of Vision in Multiple Sclerosis: Vertical Occipital Fasciculus, Its Integrity, and Visuospatial Memory

Background: Visual disturbances are a common disease manifestation and a major patient complaint in Multiple Sclerosis (MS) due to lesions damaging white matter tracts involved in vision. Vertical Occipital Fasciculus (VOF) connects ventral and dorsal visual streams and was neglected for more than a century. It has recently become under focus in brain-related disorders. Thus, its role in the visual dysfunction in MS needs to be clarified. Objective: Evaluate the integrity of bilateral VOFs in MS and its association with clinical and visual evaluations. Methods: 56 relapsing-remitting MS (RRMS) and 25 healthy controls (HC) were recruited. We acquired MS Functional Composite, Expanded Disability Status Scale (EDSS), and Brief Visuospatial Memory Test-Revised (BVMT-R), and structural and diffusion MRI scans. After VOF tractography, its integrity markers were statistically tested for between-group differences and clinical and visual tests associations. Results: RRMS patients had lower fiber integrity in bilateral VOFs compared to HC. Lower integrity of bilateral VOFs was associated with poor clinical outcomes, higher visual score in EDSS, and lower total immediate and delayed recall in BVMT-R. Conclusion: VOF damage is seen in RRMS and is associated with visual symptoms and visuospatial learning impairments.