Bidirectional trans-synaptic axonal degeneration in the visual pathway in multiple sclerosis.

Area of Science:

• Neuroscience
• Ophthalmology
• Radiology

Background:

• Multiple sclerosis (MS) is a chronic demyelinating disease affecting the central nervous system.
• Visual pathway involvement is common in MS, leading to optic neuritis and vision loss.
• Understanding the extent and mechanisms of visual pathway damage in MS is crucial for patient management.

Purpose of the Study:

• To investigate anterograde and retrograde trans-synaptic axonal degeneration in the MS visual pathway.
• To explore the relationship between visual pathway damage and global brain atrophy in MS.

Main Methods:

• Cross-sectional study of 222 MS patients and 62 healthy controls (HC).
• Analysis included optical coherence tomography (OCT) for retinal layer thickness.
• Diffusion tensor imaging (DTI) and structural MRI assessed optic radiations (OR), visual cortex, and whole-brain grey/white matter integrity.

Main Results:

• Optic neuritis in MS patients correlated with reduced OR integrity and thinner retinal nerve fibre layer (pRNFL) and ganglion cell complex (GCC).
• In MS patients without optic neuritis, OR lesion volume negatively impacted pRNFL and GCC thickness.
• Retinal thinning (pRNFL, GCC) was associated with OR integrity, visual cortex thickness, and global brain atrophy.

Conclusions:

• Evidence supports bidirectional trans-synaptic axonal degeneration in the MS visual pathway.
• Retinal thinning in MS is linked to both visual pathway pathology and widespread brain atrophy.