Investigators from Oslo University Hospital and other centers in Norway studied changes in the prevalence and incidence of multiple sclerosis (MS) in Vestfold County, Norway, in the period 1983-2003. Point prevalence was calculated for Jan 2003. The average annual incidence rates were calculated in 5-year periods from 1983 to 2002. Compared to published prevalence from 1963 and incidence from 1953, the prevalence of MS increased from 61.6/100,000 in 1963 to 166.8/100,000 in 2003. In the period 1983-2002, the annual incidence fluctuated between 4.2 and 7.3/100,000/year (mean 4.5). In 2003, the portion of MS patients with epileptic seizures was 7.4%, compared to 2.9% in 1963. During the 40 years follow-up of this population, the incidence of MS was stable, while the prevalence of MS and the share of MS patients with epileptic seizures increased. Compared to the general population, the risk of having active epilepsy was increased fourfold. 
COMMENTARY. An increased survival in MS patients is considered a reason for the present increased prevalence of epilepsy in association with MS. A MS lesion may act as a focus of an epileptic seizure .