Risk factors for unprovoked epileptic seizures in multiple sclerosis: a systematic review and meta-analysis

The role of different factors in influencing the risk of seizures during multiple sclerosis (MS) is not known. To perform a systematic review and meta-analysis of risk factors for epilepsy during MS. Pubmed, Google scholar, and Scopus databases were searched. Articles published in English (1986-2016) were included. Nine studies were included (3 retrospective cohort and 6 case-control) enrolling 2845 MS patients (217 with epilepsy; 7.6%). MS patients with epilepsy had a younger age at onset compared to MS patients without seizures (difference in means = -5.42 years, 95% CI -7.19 to -3.66, p < 0.001). Mean EDSS value at inclusion tended to be higher in patients with epilepsy, without reaching statistical significance (difference in means = 0.45, 95% CI -0.01 to 0.91, p = 0.054). No differences were observed in sex distribution (OR = 0.94, 95% CI 0.51-1.72, p = 0.83) and clinical form (OR = 1.03, 95% CI 0.33-3.21, p = 0.96). Two studies evaluated presence and number of cortical lesions as a risk factor for epilepsy in MS using different MRI techniques: in one study, cortical lesions were more frequently observed in patients with epilepsy (OR = 7.06, 95% CI 2.39-20.8; p < 0.001). In the other, cortico-juxtacortical lesions were more frequently observed in patients with epilepsy (OR = 2.6, 95% CI 1.0-6.5; p = 0.047). Studies about risk factors for epilepsy during MS are heterogeneous. Compared to MS patients without seizures, patients with epilepsy have an earlier MS onset and a higher EDSS score after similar disease duration. Clinical form of MS and sex do not predict the appearance of seizures.