Region with persistent high frequency of multiple sclerosis in Croatia and Slovenia.

Objective: The aim of this study was to evaluate the prevalence of multiple sclerosis (MS), and to determine the clinical characteristics and the occurrence of familial MS in the Gorski kotar-Kocevje region, which was previously considered to be a region of high prevalence of MS.

Methods: All clinically and laboratory supported definite cases of MS according to Poser's criteria, living residents of the chosen area on June 1, 1999 were included in the study. The patients were ascertained through national case registers for MS at the University Medical Centers (Rijeka and Ljubljana), registries of the national associations of MS patients, as well as from the medical records of regional outpatient clinics.

Results: The crude annual prevalence per 100,000 population was 151.9 (95% CI 123.2-187.4). 28.7% of patients had a history of MS among first-, second-, or third-degree relatives. The frequency of primary progressive course of disease was 23.5%. The sex ratio (F/M) was 1.41.

Conclusion: A stable high prevalence of MS as well as a high number of familial MS cases was identified in the neighbouring regions of Slovenia and Croatia.