Radiologically isolated syndrome (RIS) is the incidental finding in asymptomatic individuals of brain white matter (WM) changes meeting the Barkhof criteria for the diagnosis of MS.
This research study used brain proton magnetic resonance spectroscopic imaging (1H-MRSI) to assess metabolic changes in an RIS cohort. 23 people with RIS underwent 1H-MRSI with a central brain (CB) volume of interest (VOI) to measure levels of N-acetylaspartate (NAA) and choline (Cho) normalised to creatine (Cr) in the whole CB-VOI, in both lesional/perilesional and normal-appearing WM regions and in the cortical grey matter. This data was then compared with those of 20 matched healthy controls (HC). NAA/Cr levels were significantly lower in RIS than in HC, but there was no difference in Cho/Cr levels. NAA/Cr levels were at least 2 SDs below the HC mean in the 44% of RIS in the normal appearing white matter and in 61% of RIS in the cortical grey matter.
In conclusion, the reduced NAA/Cr level in the RIS subjects indicates likely axonal damage even at this very early stage of the disease. This information could be used in the future for stratifying RIS individuals with a high risk of progressing to MS.
Authors: Stromillo ML, Giorgio A
Source: Neurology. 2013 May 1. [Epub ahead of print]
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