Palliative epilepsy surgery in Dravet syndrome-case series and review of the literature.

PURPOSE

Dravet syndrome (DS), also known as severe myoclonic epilepsy of infancy (SMEI), is a rare genetic disorder that results in severe childhood-onset epilepsy. Children with DS initially present with seizures in the first year of life that are often associated with fevers. With age, multiple seizure types develop. There are few reports and no guidelines regarding palliative surgical treatment for DS. Therefore, we reviewed our surgical experience with DS.

METHODS

We conducted a retrospective review of all patients with genetically confirmed DS who underwent either vagal nerve stimulator (VNS) implantation or corpus callosotomy (CC) from May 2001 to April 2014 at our institution. All inpatient and outpatient relevant documentation were reviewed. Demographic information, genetic mutation, operation performed, and preoperative and postoperative seizure frequency were recorded. Inclusion criteria required greater than one-year postoperative follow-up.

RESULTS

Seven children with DS were assessed. Six patients were treated with VNS and one patient was treated with CC. In one child, VNS was followed by CC as a secondary procedure. Therefore, in total, eight surgeries were performed on seven patients during the study period. At least 1 year elapsed from presentation to our hospital and surgery for all patients. Average time after the first seizure to VNS was 4.1 years, and the average time after the first seizure to CC was 7.6 years. The mean age of patients undergoing VNS implantation was 4.3 years, and the mean age for patients undergoing CC was eight. Average follow-up for all seven patients was 6.6 years. Seizures were decreased in five of the six patients with VNS and decreased in the two patients after CC. Four of the six patients who had VNS implanted had a greater than 50 % reduction in seizure frequency, and one of the six patients who had VNS implanted had a less than 50 % reduction in seizure frequency. One patient did not respond effectively to the VNS and had very limited change in seizure frequency. Both patients who had a CC had a greater than 50 % reduction in seizure frequency.

CONCLUSIONS

Both VNS and CC in patients with DS can be effective at reducing seizure frequency. Patients with DS may benefit from earlier and more aggressive surgical intervention. Studies using larger patient cohorts will help clarify the role that surgery may play in the multidisciplinary approach to controlling seizures in DS. Further studies will help determine the appropriate timing of and type of surgical intervention.