[Brain MRI findings in Japanese patients with clinically isolated syndrome]

Treatment of patients with clinically isolated syndrome (CIS) with disease modifying drugs including interferon β delays conversion to clinically definite multiple sclerosis (MS). However, CIS patients do not necessarily develop MS even after 20 years. Brain MRI lesions were required for CIS patients to include in clinical trials such as CHAMPS study and BENEFIT study. CIS patients with brain MRI lesions compatible to MS were considered as high risk to convert to MS in western countries. Previously we reported that asymptomatic enhancing brain lesions (AEBLs) were found in 9/23 (39.1%) of MS patients who had suffered at least one relapse in the preceding year or two relapses in the preceding 2 years, and the number of AEBLs per scan was 0.37, suggesting low disease activity of Japanese MS patients. We examined brain MRI findings in Japanese CIS patients and compared with those of Japanese MS patients at the first presentation. We reviewed brain MRI of 23 CIS visited our clinic from December 2007 to October 2010 who fulfilled the criteria proposed by Kappos et al. (2006) and Dalton et al (2002). Thirty two clinically definite MS (CDMS) patients fulfilled the first McDonald criteria (two or more attacks and objective clinical evidence of two or more lesions) proposed by Polman et al. (2005). Patients with neuromyelitis optica (NMO) and patients with NMO spectrum proposed by Wingerchuk et al. (2006) and Wingerchuk et al. (2007), respectively, were excluded. Patients with anti-aquaporin4 antibodies or with contiguous spinal cord lesion extending over three vertebral segments on MRI were also excluded. We could not obtain MRI of 11 patients with CDMS because of very long disease course, and 2 CIS and 13 CDMS patients had not been examined with MRI. So we examined 21 CIS and 8 CDMS patients at the first presentation using Paty criteria and Barkhof criteria. Eleven CIS patients did not meet any of the Barkhof criteria. Seven and 3 CIS patients met one and two of Barkhof criteria, respectively. No CIS patients showed fulfilled more than 3 of Barkhof criteria. Seven of eight CDMS patients at the first presentation showed more than one of the Barkhof criteria, however, only one CDMS patient at the onset fulfilled more than 3 of the Barkhof criteria. Japanese CIS patients seemed to show less brain lesions than those in western countries.