Decrease in multiple sclerosis with acute transverse myelitis in Japan

Acute transverse myelitis (ATM) may be a manifestation of multiple sclerosi s (MS) and was reported to be more common among Japanese MS patients than i n Caucasian MS patients, Recently there are arguments whether clinical mani festations of MS may have changed. Therefore, we studied the frequency of A TM in MS and the clinical subtypes of MS in 86 clinically definite MS patie nts whose onsets were in 1970-1979, 1980-1989, and 1990-1998 in Sendai City , Japan. fifty-six of the patients were women and 30 were men. forty-four p atients had the conventional form of MS (C-MS) commonly seen in Western cou ntries, and 42 had optic-spinal or spinal forms of MS (OSS-MS). Twenty MS p atients had ATM, and all of them were belong to optic-spinal form of MS. AT M was not seen in any cases of C-MS. The mean onset age (years) of the clin ical subtypes was 25.5 in C-MS, 34.1 in OSS-MS without ATM, and 30.9 in OSS -MS with ATM. Among the patients whose onset of the disease was in 1970-197 9, 60.0% of them were ca,ses of OSS-MS with ATM, but such cases were marked ly decreased to 5.3% in 1990-1998. In contrast, the frequency of C-MS incre ased to 63.2% in 1990-1998 compared with 20.0% in 1970-1979. Analysis of th e data by the year of birth of the patients showed similar results. Our dat a suggest that the frequency of ATM in MS markedly decreased, and that of C -MS increased during the last 30 years in Sendai, Japan. Since the genetic background of Japanese has not changed, some exogenous factors, such as foo d, infectious microorganisms, and chemicals in our environment, may be resp onsible for the change. (C) 1999 Tohoku University:Medical Press.