MRI only conversion to multiple sclerosis following a clinically isolated syndrome
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Using current diagnostic criteria, people who present with a clinically isolated episode (CIS) may develop multiple sclerosis (MS) by subsequently exhibiting dissemination in space and time on clinical or radiological grounds. This study investigated the frequency of radiological without clinical conversion to MS. Chard DT, Dalton CM, Swanton J, Fisniku LK, Miszkiel KA, Thompson AJ, Plant GT, Miller DH. J Neurol Neurosurg Psychiatry. 2010 Jun 2. ( Epub ahead of print)
Using current diagnostic criteria, patients who present with a clinically isolated syndrome (CIS) may develop multiple sclerosis (MS) by subsequently exhibiting dissemination in space and time on clinical (clinically definite (CD) MS) or radiological (MRI) grounds. This study investigated the frequency of radiological without clinical conversion to MS after long term follow-up as this has not previously been defined.
Two cohorts who underwent serial clinical and MRI studies from presentation with a CIS and who were followed-up over a mean of 6 and 20 years were investigated. The distribution and formation of lesions visible on brain MRI were assessed using the revised McDonald criteria (2005). Radiologically defined (RD) MS was determined by fulfilment of the MRI but not the CDMS criteria.
105 people were followed-up for 6 years after a CIS, of whom 51% developed CDMS, 15% RDMS and the remainder were classified as still having had a CIS. 70 people were followed-up at 20 years, of whom 61% and 11% had developed CDMS and RDMS, respectively. Authors conclude that about 10-15% of CIS patients may develop MS on MRI criteria only, without further clinical events for up to two decades.