DSF has received many questions about epilepsy surgery for patients with Dravet syndrome recently. If this is something you are considering for your child, it is crucial to know your options and to learn more about what we currently know regarding surgery for patients with Dravet syndrome.
It is important to remember that every patient’s seizures are unique. Surgery in epilepsy is sometimes considered for patients with intractable epilepsy, whose seizures are not well-controlled. In general, epilepsy surgery is more effective for focal or partial seizures that originate in specific regions of the brain and do not spread globally or come from multiple areas throughout the brain. In Dravet syndrome, while initial seizure activity can appear to be more focal in origin, the underlying genetic cause and usual progression to generalized seizures have led to less successful outcomes for individuals with Dravet syndrome following palliative epilepsy surgery (Bremer et al, 2012). However, while procedures to surgically alter the physical connections of the brain have been less successful, vagus nerve stimulation (VNS) has had more varied success among patients with Dravet syndrome, in many cases improving seizure control.
- Vagus nerve stimulation, or VNS, is an implantable device that stimulates the vagus nerve. VNS uses mild electrical pulses to help regulate the electrical activity in the brain. Regular pulses help to reduce the baseline risk of seizures and an external magnet can be used to activate the device during an active seizure to help stop the seizure. While still generally thought to be more effective for treating focal or partial seizures, VNS is still commonly used by patients with Dravet syndrome with varied success. A 2016 study reported 4 out of 6 individuals with Dravet syndrome had a >50% reduction in seizures following VNS implantation (Dlougy et al 2016), but a 2012 study reported only 1 patient out of 13 who had similar seizure reductions after VNS surgery (Bremer et al 2012). In a North American Consensus Study, VNS was considered a third line treatment consideration for individuals with Dravet syndrome. The panel of expert clinicians reached moderate agreement that VNS should be considered after failure of first- and second-line treatments (Wirrell et al 2017). You can read more about VNS Therapy from the Epilepsy Foundation or The Brain Recovery Project.
- Other epilepsy surgeries, such as a temporal lobectomy (removing the area of the brain where the seizures are originating) or corpus callosotomy (disrupts the pathways and limits the spread of epileptic activity between the two halves of the brain) have much less evidence of success in Dravet syndrome. As mentioned above, these types of surgeries are often more successful in patients with focal or partial seizures where at-risk brain regions can be identified. Even in instances where seizures appeared localized in origin, patients with Dravet syndrome appeared to be less responsive to these types of surgical interventions leaving the researchers to conclude that patients with Dravet syndrome are not ideal candidates for epilepsy surgery even when the preoperative work-up suggests focal lesions that should be responsive to surgery (Barba et al 2014 <2 patients>, Vezyroglou et al 2020 <3 patients>, Skjei et al 2015 <6 patients>). However, there have been rare instances where patients with Dravet syndrome have seen benefit following corpus callosotomy (Dlougy et al 2016 <2 patients>). Additionally, some researchers have suggested that while patients with Dravet syndrome may not be ideal candidates for effective epilepsy surgery, other SCN1A-related epilepsy syndromes may still find success with these types of approaches (Vezyroglou et al 2020).
If you are considering surgical intervention for your child, it is important to have a surgical evaluation done at a facility that is a level 4 pediatric epilepsy center and with a team who is familiar with Dravet syndrome and its trajectory and complexities. The Brain Recovery Project offers helpful guidelines on surgical evaluation to assure that you understand all of your options before making this difficult decision.
References: Barba et al 2014, Epilepsia; doi: 10.1111/epi.12658 Bremer et al 2012, Acta Neurol Scand; doi: 10.1111/j.1600-0404-2011.01609.x Dlougy et al 2016, Child Nerv Syst; doi 10.1007/s00381-016-3201-4 Skjei et al 2015, J Neurosurg Pediatr; doi: 10.3171/2015.5.PEDS14551 Vezyroglou et al 2020, Develop Med & Child Neurology; doi: 10.1111/dmcn14588 Wirrell et al 2017, Pediatric Neurology; doi: 10.1016/j.pediatrneurol.2017.01.025