The production of IL-6 in acute epileptic seizure: A video-EEG study

Experimental and clinical reports highlight the role of cytokines in pathophysiological processes in underpinning epilepsy, but the clinical data remains somewhat limited. The levels of Interleukin (IL)-6 were measured in serum from 49 patients with refractory epilepsy [temporal lobe epilepsy (TLE, n=23), extratemporal lobe epilepsy (XLE, n=22), and idiopathic generalized epilepsy (IGE, n=4)] before and after the first verified seizure (IS; index seizure) during inpatient video-electroencephalographic (VEEG) monitoring. The levels of IL-6 increased significantly at all time points between 3h and 24h after the IS compared to the baseline. IL-6 concentrations were significantly higher at the 3h and 6h time point after tonic-clonic seizures (TCS) compared to the situation with simple partial and complex partial seizures. An IS duration longer than 100s, low baseline IL-6 level and <10 seizures/month in patients with TLE were associated with an increase in IL-6 concentrations during the 24h after the IS. In patients with TLE, the maximum change in IL-6 levels after IS was significantly higher than in XLE. If the baseline level of IL-6 was low (under 5pg/ml), seizures induced a significant elevation in both absolute and relative values in TLE patients but not in XLE. In patients with ≤10 seizures per month during the last year, the maximum change was higher than in patients with >10 seizures. If the total seizure burden during registration was ≥100s, the IL-6 increase was significantly higher than if it were under 100s. The results of this study highlight the complexity of factors involved in the seizure induced production of the inflammatory cytokine, IL-6. The major factor is the epilepsy type i.e. increased production of IL-6 in TLE compared to XLE. The response to a single seizure in TLE is dependent on the previous seizure frequency and the baseline IL-6 concentration.