Background and aim: Conversion to multiple sclerosis (MS) after optic neuritis and myelitis has been thoroughly studied; however, limited data are available regarding conversion to MS after a clinically isolated syndrome of the brainstem (CISB). The aim of this study was to investigate conversion to MS in patients with CISB.
Methods: Fifty-one patients with CISB were prospectively studied. Cranial magnetic resonance imaging (MRI), determination of oligoclonal bands (OBs) in the cerebrospinal fluid (CSF) and evoked potentials (EPs) were performed. Based on conversion to MS at follow-up, the sensitivity, specificity, accuracy and positive and negative predictive values of these tests were calculated.
Results: Clinically definite MS developed in 18 (35%) patients after a mean follow-up of 37 months. Paty's MRI criteria showed a sensitivity of 89%, a specificity of 52% and an accuracy of 65%; Fazekas' criteria showed a sensitivity of 89%, a specificity of 48% and an accuracy of 63%; Barkhof's criteria showed a sensitivity of 78%, a specificity of 61% and an accuracy of 67%. The presence of OBs in the CSF showed a sensitivity of 100%, a specificity of 42% and an accuracy of 63%. No differences for neurophysiological parameters were found between patients who did and those who did not convert to MS.
Conclusion: Fulfilling Paty's, Fazekas' or Barkhof's MRI criteria and the presence of OBs in the CSF are associated with a higher risk of conversion to MS in patients with CISB. Determination of OBs in the CSF has the greatest sensitivity of all tests. Barkhof's MRI criteria have greater specificity (although less than previously published for mixed cohorts of clinically isolated syndromes) in predicting conversion to MS for CISB than either Paty's or Fazekas' criteria.