Late-onset multiple sclerosis in Isfahan, Iran

ABSTRACT

Multiple sclerosis [MS] typically affects young adults; however, the first symptoms can occur after age 50 and is classified as late-onset MS [LOMS]. In this retrospective study, we extracted the records of 3522 MS patients [2716 females and 806 males] registered in the Isfahan MS Society [IMSS] from 2003 to 2010. Next, we searched for LOMS cases. We aimed to compare these cases with 1698 non-LOMS subjects also extracted from the IMSS database. We found 48 LOMS patients [28 females and 20 males], which gave a crude frequency of 1.36%. The frequency by sex of LOMS in males [2.4%] was significantly greater than in females [1.0%, P = 0.002]. The mean age at onset was 55.1 +/- 4.3 years. The female to male ratio of 1.41 in these patients was significantly lower than in non-LOMS subjects [3.371, P= 0.003]. The leading pattern of MS was relapsing-remitting [RR] in 62.5%, followed by primary progressive [PP] in 27.1%, and secondary progressive [SP] in 10.4%. Predominant presenting symptoms and signs were motor disturbances [35.4%], followed by brainstem [25%], optic neuritis [22.9%], and sensory related deficits [18.7%]. The mean progression index [PI] in LOMS patients [0.88 +/- 0.48] was significantly higher than in non-LOMS cases, 0.37 +/- 0.17 [P< 0.0001]. In comparing LOMS patients with the non-LOMS cohort, there was a higher frequency of the PP pattern and a higher PI in the LOMS group. In comparing other high-risk populations with the Isfahan cohort, LOMS formed a lower percentage of the total Isfahan MS population