Researchers discovered that the gray matter lesions present in relapsing-remitting multiple sclerosis (MS) differ from those in neuromyelitis optica spectrum disorder (NMOSD) and published their results in the Journal of Neuroscience Research

MS and NMOSD are both characterized by the chronic inflammatory demyelination of the central nervous system. The link between these 2 diseases was close enough that NMOSD was once considered a subset of MS.

“Histopathological studies have suggested that the [gray matter] in MS was affected from the earliest stage by demyelination, neuronal loss, and neuroinflammation. In contrast, the [gray matter] was significantly less affected in NMOSD, with an absence of demyelination,” Andica and colleagues wrote.

Continue Reading

To conduct their study, the research team set out to characterize the spatial distribution and extent of gray matter alterations in patients with relapsing-remitting MS and NMOSD. Their aim was to highlight the association between gray matter pathologies and clinical disability scores and disease duration.

They recruited 66 participants for their retrospective case-controlled study, comprising of 30 patients with relapsing-remitting MS, 18 patients with NMOSD, and 19 healthy controls. The participants underwent whole-brain multi-shell diffusion-weighted imaging, 2-dimensional synthetic magnetic resonance imaging, and 3-dimensional T1-weighted imaging.

Read more about NMOSD testing

The researchers discovered the following: 

  • Neurite loss in relapsing-remitting MS demonstrated mainly localized change, while the patterns seen in NMOSD demonstrated more widespread involvement.
  • Substantial cortical neuronal loss without the presence of demyelination and neuroinflammation was observed in NMOSD compared to patients with relapsing-remitting MS and the control group. 
  • Gray matter pathology drove disease progression and disability in relapsing-remitting MS. 
  • A significantly lower volume was observed in the thalamus, caudate, and putamen in relapsing-remitting MS compared to NMOSD (only the thalamus and the caudate) and healthy controls.

“Our results suggested extensive neuroinflammation, along with a lesser extent demyelination and neuronal loss, predominantly in the limbic and paralimbic regions, was substantially associated with disease progression and disability in [relapsing-remitting MS],” the authors said.

“In contrast, we observed substantial neuronal loss with no evidence of demyelination and neuroinflammation, mainly in the cerebellar, limbic, and paralimbic cortices in patients with NMOSD.”


Andica C, Hagiwara A, Yokoyama K, et al. Multimodal magnetic resonance imaging quantification of gray matter alterations in relapsing-remitting multiple sclerosis and neuromyelitis optica spectrum disorderJ Neurosci Res. Published online March 22, 2022. doi:10.1002/jnr.25035