Relevance of the study of oligoclonal bands as a prognostic factor of the conversion of clinically isolated syndrome into clinically definite multiple sclerosis in daily practice

Background: In daily practice, when we are in presence of a clinically isolated syndrome (CIS), magnetic resonance imaging (MRI) is currently the most important supplementary exam to establish the risk for developing clinically definite multiple sclerosis (CDMS). In this perspective the cerebrospinal fluid study seems to have been relegated to the background. Objective: Evaluate as a prognostic factor of the conversion of CIS into CDMS the presence of oligoclonal bands (OB) in the lumbar puncture. Methods: For this study we have selected patients having presented a CIS between January 1st 2003 and December 31st 2005, and who have undergone, at a teaching hospital, a lumbar puncture so as to identify potential presence of OB. All the patients have undergone medullar and cerebral MRI, to which we have retrospectively applied the Barkhof criteria (BC). We diagnosed the conversion to CDMS when a second attack occurred before March 2008. Results: We studied 72 patients with CIS (sex ratio women/men=4/5; mean age=35 years. In the group of patients presenting the BC (n=33) in the baseline MRI, the presence of OB was predictive of CDMS in 74% of them. However, a CDMS occurred for three patients who were OB negative. In the group of patients not presenting the BC (n=39), the presence of OB was predictive of CDMS in 59% of them. However, a CDMS occurred for six patients who were OB negative. For our center we obtained a sensitivity of 51% for BC versus 65% for presence of OB, and a specificity of respectively 64% versus 32%. Conclusions: In the presence of a CIS, combining OB and an MRI that does not meet the BC improves the accuracy of our forecast of CDMS. Nevertheless, our results remain lower than those of prospective studies on selected populations, probably due to the short timescale of the study.