Radiologically isolated syndrome (RIS) is where someone with no symptoms of MS has a brain scan that show abnormalities suggestive of MS. A number of MRI studies have shown that brain damage in RIS is similar to that of MS.
Both anatomical and functional connectivity – different problems in the brain – are altered in the brains of people with MS.
An MRI technique called diffusion tensor imaging is used to look at white matter tracts and anatomical connectivity. Another MRI technique, resting functional MRI, looks at grey matter and functional connectivity.
A group of researchers from the University of Siena enrolled 18 asymptomatic subjects with RIS and 20 people with relapsing-remitting MS.
Anatomical connectivity was similar in normal controls and RIS subjects, and increased in relapsing-remitting MS patients. This means that in RIS subjects there is less damage to white matter than in people with MS.
Brain connectivity of RIS subjects could represent a model of functional reserve, which may be affected only at a later stage in case of occurrence of clinical deficit and conversion from RIS to MS. Capturing temporal dynamics of brain connectivity changes in RIS subjects who will or will not convert to MS over time may help to better understand the mechanisms that leads to conversion to MS.