Partial response to the vagus nerve stimulation in twins with double cortex syndrome

We report twins sister 16 years of age, with double-cortex-syndrome, due to a mutation of the DCX gene on exon 7. Typical symptoms include severe mental and motor retardation, epileptic seizures and muscular hypotonia. The sisters suffer from primarily generalised seizures including absences, myoclonic and astatic seizures and severe grand mal seizures. Additionally complex focal seizures occur regularly. One sister has tonic-clonic seizures, the other sister drop attacks. Both sisters have up to 10 seizures a day, the GM occurring every few days. The EEG was slow in its background activity, generalised irregular spike waves activity up to a duration of 25 seconds respectively.

As numerous medications failed to improve seizure control a VNS device was implanted in in 2007. The additional on-demand stimulation in the case of beginning GM seizures proved to be able ton interrupt grand mal seizures in both girls, this effect being apparent already in the second week after VNS implantation. The frequency of petit mal seizures, however, could not be influenced. The acute effect of the on-demand stimulation declined in one sister in the course of time, the output current was hence increased. Nevertheless the seizures could subsequently not always be interrupted. The stimulation has to be carried within a short interval of less than 1 minute in both girls in order to be effective. Both sisters report an improved general condition and wee being after VNS implantation. The girls currently have a an anticonvulsive therapy with phenobarbitone and topiramate as well as with oxcarbazepine and stiripentol, respectively. VNS parameters: time on 30 seconds, time off 5 minutes, output current 1.25 mvolt, magnet current 1.5 mvolt. Even in severe brain malformation VNS can partially successful and this option can also be considered in similar patients.