Nonconvulsive Status Epilepticus - A Possible Cause of Mental Retardation in Patients with Lennox-Gastaut Syndrome - Hoffmann-Riem, M; Diener, W; Benninger, Chr; Rating, D; Unnebrink, K; Stephani, U; Ernst, H -P; Korinthenberg, R (Neuropediatrics, 2000)