Epileptic seizures in multiple sclerosis: a population-based survey in Iran.

No large population-based survey has until now been carried out on the linkage of epilepsy (EP) and multiple sclerosis (MS) either in the middle-east or in Asia. In this retrospective population-based study (April 2003 to July 2010) on the total Isfahan cohort of 3,522 Iranian MS patients, we looked for EP/MS patients and compared their features with 1,665 non-EP/MS cases. We identified 105 cases, though, 24 were excluded for an implausible EP/MS link. Among 81 (2.3 %) eligible cases, EP occurred (1) within a mean duration of 5.6 ± 5.4 years after the development of MS in 64 cases (79 %); (2) at MS onset as the presenting symptom in five cases (6.2 %); and, (3) by a mean duration of 4.3 ± 4.3 years prior to onset of MS in 12 patients (14.8 %). The overall mean ages at MS onset and at the first seizure episode were 28.5 ± 11.2 years and 32.5 ± 14.0 years, respectively. Regarding the age at onset of MS, 12.3 % of EP/MS patients were classified as early-onset; 81.5 % as adult-onset; and 6.2 % as late-onset. Such frequencies were statistically different (P < 0.0001) from those of the 1,665 control non-EP/MS patients (5.9; 93.0 and 1.1 %, respectively). Regarding the pattern of MS, EP/MS patients were classified as relapsing-remitting, secondary progressive, and primary progressive in 60.5, 25.9, and 13.6 %, respectively. This configuration differed (P < 0.0001) from that of non-EP patients (87.9; 6.3 and 5.7 %, respectively). Our results are suggestive of differences between EP/MS and non-EP/MS cases as regards the proportion of MS patterns and age-at-onset classifications.