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.