When would you obtain optic nerve testing in patients suspected to have multiple sclerosis without a clinical history of optic neuritis?

A key change in the 2024 revision of the McDonald criteria is the addition of the optic nerve as a fifth anatomic location to demonstrate dissemination in space (DIS) in addition to periventricular, cortical/juxtacortical, infratentorial, and spinal cord, which were included in the 2017 criteria. Optic nerve involvement can be demonstrated using any one of orbital MRI, optical coherence tomography (OCT), or visual evoked potentials (VEP). While there is utility in routinely performing baseline assessment of the optic nerve among patients with either suspected or confirmed MS, there are two specific scenarios in which optic nerve assessment may facilitate diagnosis using the 2024 criteria. Firstly, optic nerve testing is recommended when onl...

Occasionally, to pick up subclinical disease in making an early diagnosis, I will request pattern-shift VEP. Picking up a silent lesion can help with the "dissemination in space" criteria, now that the optic nerve is considered part of the topography for MS lesion location in the new diagnostic criteria.

One should start with perimetry. After analysis, OCT and or MRI can be specifically added. MRI is not sensitive except in the acute/subacute phase. OCT findings are non-specific, as are VEP findings. A neuro-op exam coupled with some testing is the best way to be sure any lesion is related to a potential diagnosis of MS.

Assuming it's acute optic neuritis, start with the basics:

1. Swinging flashlight test to screen for an afferent pupillary defect.
2. Assess red desaturation with a Tropicamide bottle cap (which neurologists sadly don't carry).
3. Dilated fundus exam to screen for papillitis/maculopathy/increased cup-disk ratio of glaucoma. Most neurologists skip this step.
4. OCT with special attention to the thickness of ganglion cell/inner plexiform layers NOT nerve fiber layer (remember it's acute).
5. MRI of brain and orbits w and w/o contrast (and it will still miss ~10% of optic neuritis plaques b/c optic nerve is small and sinuous and plaques may be elusive).
6. Automated perimetry, assuming you can distinguish scotomas. Central? Cecocentral? Arcuate? ( The print-ou...