The forgotten tract of vision in multiple sclerosis: vertical occipital fasciculus, its fiber properties, and visuospatial memory

AmirHussein Abdolalizadeh, Soheil Mohammadi, Mohammad Hadi Aarabi
Brain Structure and Function. 2022-02-17; 227(4): 1479-1490
DOI: 10.1007/s00429-022-02464-3

1. Brain Struct Funct. 2022 May;227(4):1479-1490. doi:
10.1007/s00429-022-02464-3. Epub 2022 Feb 17.

The forgotten tract of vision in multiple sclerosis: vertical occipital
fasciculus, its fiber properties, and visuospatial memory.

Abdolalizadeh A(1)(2), Mohammadi S(3)(4), Aarabi MH(5).

Author information:
(1)Interdisciplinary Neuroscience Research Program, Tehran University of Medical
Sciences, No. 56, Vesal St., Keshavarz Blvd., 1417755331, Tehran, Iran.
.
(2)Students’ Scientific Research Center, Tehran University of Medical Sciences,
No. 56, Vesal St., Keshavarz Blvd., 1417755331, Tehran, Iran.
.
(3)Faculty of Medicine, Tehran University of Medical Sciences, Poursina St.,
Keshavarz Blvd., Tehran, Iran.
(4)NeuroImaging Network (NIN), Universal Scientific Education and Research
Network (USERN), Children’s Medical Center, Dr. Gharib St, Keshavarz Blvd,
1419733151, Tehran, Iran.
(5)Department of Neuroscience, Padova Neuroscience Center, University of Padova,
Via Orus 2/B, 35129, Padua, Italy.

Visual disturbances are a common disease manifestation in multiple sclerosis
(MS) due to lesions damaging white matter tracts involved in vision. Vertical
occipital fasciculus (VOF), a tract located vertically in the occipital lobe,
was neglected for more than a century. We hypothesize that VOF is involved in
integrating information between dorsal and ventral visual streams. Thus, its
damage in MS, as well as its probable role in visual processing (by using MS as
a VOF damage model) needs to be clarified. To study fiber characteristics of VOF
in MS, and their clinical and visual learning associations, 57
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 diffusion MRI scans.
Tractography of VOF and optic radiation (OR) was done. VOF’s metrics were
statistically tested for between-group differences and clinical and visual tests
associations. Along-tract analysis and laterality were also tested. RRMS
patients had higher mean, axial, and radial diffusivity (nearly in all fiber
points), and lower fractional anisotropy in bilateral VOFs compared to HC. No
laterality was noted. These were associated with poor clinical outcomes, poor
visual scores in EDSS, and lower total immediate and delayed recall in BVMT-R in
RRMS, after adjusting for age, gender, and fiber metrics of OR. VOF damage is
present in RRMS and is associated with visual symptoms and visuospatial learning
impairments. It seems VOF is involved in integrating information between visual
streams.