A dam for retrograde axonal degeneration in multiple sclerosis?

Area of Science:

• Neuroscience
• Ophthalmology
• Neurology

Background:

• Trans-synaptic axonal degeneration is a key mechanism in the spread of neurodegeneration.
• Understanding this process in the visual pathway is crucial for multiple sclerosis (MS) research.

Purpose of the Study:

• To investigate the extent of trans-synaptic axonal degeneration within the visual pathway in patients with MS.
• To compare degeneration patterns in MS with and without a history of optic neuritis.

Main Methods:

• A single-centre study utilizing structural MRI and spectral-domain optical coherence tomography.
• Quantification of retinal layer and visual cortex atrophy in 230 MS patients and 63 healthy controls.
• Statistical analysis using generalized estimation equations and multivariable regression.

Main Results:

• Significant atrophy of inner retinal layers was observed in MS, even without optic neuritis, ceasing at the inner nuclear layer.
• Localized atrophy of the primary and secondary visual cortex occurred in MS following optic neuritis.
• No significant visual cortex atrophy was found in MS patients without a history of optic neuritis.

Conclusions:

• Retrograde trans-synaptic axonal degeneration in MS appears limited by the plasticity of the inner nuclear layer.
• The primary visual cortex lacks neuroplasticity, making it susceptible to anterograde trans-synaptic degeneration in MS.