Preclinical Neuroaxonal Injury in Radiologically Isolated Syndrome

A preliminary study demonstrates neuroaxonal injury in a small cohort of patients with RIS.

Radiologically isolated syndrome (RIS) is the incidental finding of classic, demyelinating-appearing white-matter alterations on brain magnetic resonance imaging (MRI) in someone without clinical symptoms of demyelination. Imaging may have been prompted by other diagnostic considerations, such as trauma or headaches. To further investigate the pathology detected with MRI in this patient population, researchers recruited 23 patients with RIS (median age, 39.7; range, 19–59), along with 20 matched controls. Cerebrospinal fluid was positive for inflammatory changes in 14 of 19 patients tested, and spinal cord abnormalities were detected in 8 of 19. Dissemination in time was demonstrated in 9 of 23 by additional abnormalities on a second MRI.

In people with RIS, the ratio of N-acetylaspartate to creatine level (NAA/Cr) was decreased in lesional/perilesional white matter, normal-appearing white matter, and cortical gray matter. Compared with the ratio in controls, NAA/Cr was at least two standard deviations below the mean for 39% of participants with RIS in whole central brain, 44% in normal-appearing white matter, and 61% in cortex. The decreased NAA/Cr was not clearly related to T2 lesion burden.

CITATION(S):

Stromillo ML et al. Brain metabolic changes suggestive of axonal damage in radiologically isolated syndrome. Neurology 2013 May 1; [e-pub ahead of print].