Video/EEG findings in a KCNQ2 epileptic encephalopathy: a case report and revision of literature data

Abstract

We describe the EEG findings of an infant with early-onset epileptic encephalopathy with mutation of the KCNQ2 gene and a family history of neonatal seizures. The infant presented with multifocal drug-resistant seizures with onset during the third day of life. Family history was positive for early-onset neonatal seizures. Metabolic screening and neuroimaging were negative. Direct sequencing of KCQN2 from both the mother and child revealed a heterozygous cytosine-to-guanine mutation (Dedek et al., 2003). Interictal EEG showed a very discontinuous pattern which evolved towards a defined burst-suppression pattern during sleep and a multifocal, random, attenuation pattern during wakefulness. Focal, tonic seizures with head deviation, sometimes followed by asynchronous and asymmetrical clonic jerks, eyelid myoclonias, and polypnoea, were recorded. Ictal EEG was characterised by focal, low-voltage, fast activity, followed by recruiting theta rhythms and bilateral, focal, spike-wave complexes, alternatively localised to one hemisphere and subsequently diffusing to the other. ACTH therapy was introduced, resulting in a significant improvement in EEG activity and gradual reduction in seizure frequency, with cessation at age 13 weeks. [Published with video sequences].

Keywords: KCNQ2; burst-suppression; encephalopathy; epilepsy; infant.