Introduction: Epilepsy is three to six times more frequent in MS than in the general population. Previous studies based on conventional magnetic resonance (MR) imaging have suggested a possible correlation between cortical inflammatory pathology and epileptic seizures. However, pure intracortical lesions (ICLs) are unlikely to be demonstrated with conventional MR. We applied the double inversion recovery (DIR) sequence in relapsing remitting MS (RRMS) patients with or without epileptic seizures in order to clarify the relationship between ICLs and epilepsy in MS in vivo.
Methods: Twenty RRMS patients who had epileptic seizures (RRMS/E) during the course of the disease were studied for the presence of ICLs. A group of 80 RRMS patients with no history of seizures and matched for gender, age, disease duration, Expanded Disability Status Scale (EDSS) grading, and T2 lesion volume (T2-WMLV) was selected as reference population. ICLs were detected by applying the DIR sequence.
Results: ICLs were observed in 18/20 (90%) RRMS/E and in 39/80 (48%) RRMS (p = 0.001). RRMS/E showed five times more ICLs (7.2 +/- 8.4) than RRMS (1.5 +/- 2.4; p = 0.015). The total ICLs volume was 6 times larger in RRMS/E than in RRMS (1.2 +/- 1.7 cm3 versus 0.2 +/- 0.2 cm3, p = 0.016). No significant difference was observed between RRMS and RRMS/E with regard to the number and volume of juxtacortical lesions and T2-WMLV.
Discussion: Our findings indicate that RRMS/E have more extensive cortical inflammation than RRMS patients with no history of epilepsy. Inflammatory ICLs may be responsible for epilepsy in MS.