Researchers have identified that differences in total N-acetylaspartate (tNAA) levels in the cervical spinal cord can help identify clinico-radiological subgroups containing patients with neuromyelitis optica spectrum disorder (NMOSD) who have distinct underlying disease processes, according to a study published in the Multiple Sclerosis Journal.

NMOSD is a group of central nervous system inflammatory disorders. Despite many of its characteristics overlapping with multiple sclerosis (MS), the two are distinct diseases in terms of etiology, treatment response, and prognosis. 

The main subtype of NMOSD is seropositive for anti-aquaporin-4 (AQP4) antibodies. However, identifying and treating patients who are antibody negative has proven to be a challenge due to a lack of biomarkers. The authors of this study hence investigated whether magnetic resonance spectroscopy could be used to quantify the differences in spinal cord metabolite levels between the various subgroups of antibody-negative NMOSD. 

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The research team recruited 25 patients who underwent a brain and spinal cord structural nonconventional imaging scan and had confirmed antibody-negative NMOSD. Subsequently, participants underwent magnetic resonance spectroscopy of the cervical spinal cord. The researchers also obtained conventional magnetic resonance imaging data from patient files. 

Read more about NMOSD epidemiology 

The authors of the study were specifically looking at levels of tNAA, total choline, and myo-inositol in patients with antibody-negative NMOSD. They discovered that tNAA levels were significantly lower in the “multiple sclerosis-like” subgroup of antibody-negative NMOSD than in the “classic NMOSD-like” subgroup. 

“Spinal cord [magnetic resonance spectroscopy] is a promising tool to study underlying pathology in MS/NMOSD overlap patients since both MS and NMOSD show predilection for the spinal cord,” the authors of the study concluded. 

In this study, spinal cord magnetic resonance spectroscopy was demonstrated to be useful in elucidating the heterogeneity of the disease process in patients with antibody-negative NMOSD, and classification based on clinico-radiologic signature better captured the complexity of antibody-negative NMOSD compared to existing diagnostic criteria.


Kossowski B, Kong Y, Klimiec-Moskal E, Emir U, Palace J, Juryńczyk M. Relapsing antibody-negative patients with features of neuromyelitis optica spectrum disorders: differences in N-acetylaspartate level in the cervical spinal cord indicate distinct underlying processesMult Scler. Published online August 15, 2022. doi:10.1177/13524585221115304