Antiepileptic therapy approaches in KCNQ2 related epilepsy: A systematic review

Background: KCNQ2 related disorders comprise both benign seizure disorders and early onset epileptic encephalopathies. Especially within the latter group, patients suffer from refractory seizures to standard antiepileptic drugs and developmental delay. Besides the hope of personalized medical approaches to treat the recently unraveled large amount of genetic channelopathies, there are sparse systematic data on treatment responses in KCNQ2 related epilepsy in larger cohorts. Methods: We searched PubMed using the free text term search 'KCNQ2 AND Epilepsy' and identified additional records using PubMed Medical Subject Headings (MeSH). Based on patients' clinical information about their therapy they were assigned to one of four groups: 'seizure freedom', 'responder', 'successful therapy', and 'unsuccessful therapy'. Results: Out of 52 studies, 217 subjects were eligible for further data analyses. 133 patients were classified as 'benign' seizure disorders whereas 84 patients were classified as 'Early Onset Epileptic Encephalopathy (EOEE)'. In the 'benign' group, 92.5% of patients became seizure free while 3.8% did not respond to treatment. In contrast 65.5% of patients in the 'EOEE' group were reported seizure free, while 14.3% showed no treatment success (p = 0.003). Spontaneous seizure remission (without medication) was 30.1% in the 'benign' group. Phenobarbital and sodium channel blockers most often lead to seizure freedom in patients with a 'benign' course. In patients with 'EOEE' seizure freedom was more likely achieved when receiving sodium channel blockers. Conclusions: Seizures associated with mutations within the voltage gated potassium channel KCNQ2 are well controlled by medical treatment in patients with 'benign' courses and moderately well in patients with the 'EOEE' group. A significant number of patients in the 'benign' group may experience seizure freedom spontaneously. Phenobarbital might be considered in benign courses, while sodium channel blockers seem appropriate for both 'benign' and 'EOEE' patients.