Abstracts

Rationale: Dravet syndrome is an intractable developmental and epileptic encephalopathy that begins in infancy characterized by frequent focal and generalized seizures often resistant to medications. Neuromodulation devices such as vagus nerve stimulation (VNS), deep brain stimulation (DBS), and responsive neurostimulation (RNS) offer alternative approaches to treating patients with drug-resistant epilepsy (DRE). RNS detects and responds to abnormal brain activity, receiving FDA approval for adults with focal epilepsy. Emerging evidence also supports its use in pediatric patients and in generalized epilepsies, particularly targeting the bilateral thalamic regions. Evidence suggests that VNS may offer benefit in patients with Dravet syndrome, but there is limited evidence supporting other neuromodulating devices with no current reports of RNS implantation in this population.

Methods: We present a pediatric patient with Dravet syndrome who experienced improvement in seizure frequency following RNS implantation.

Results: A 7-year-old female with Dravet syndrome with confirmed pathogenic SCN1A variant, developmental delay, and DRE presented with myoclonic, atonic, hemiclonic, and generalized tonic-clonic seizures. She was experiencing >100 seizures per day, predominantly myoclonic and atonic, with frequent episodes of status epilepticus. Antiseizure medications (ASMs) included brivaracetam, cannabidiol, and fenfluramine. Prior ASMs included zonisamide, levetiracetam, and clobazam. Scalp EEG demonstrated frequent, asymmetric, irregular generalized epileptiform discharges occurring in bursts of variable duration. Brain MRI did not identify epileptic foci for seizures. In May 2023 she underwent intracranial EEG with bilateral depth electrode array which captured >200 electroclinical myoclonic, atonic, and myoclonic-atonic seizures with diffuse onset or with first electrographic change in the bilateral centromedian nucleus of the thalamus (CMT) electrodes. RNS was subsequently implanted with bilateral CMT depth electrodes. Electrocorticography (ECoG) data following RNS implantation revealed frequent episodes of spike wave discharges consistent with previously captured myoclonic seizures on intracranial EEG. RNS long episodes initially declined substantially over ~2 months with ongoing improvement in seizure frequency upon increasing charge density. Clinically, atonic and myoclonic seizures demonstrated the most robust improvement. At time of most recent clinic visit, the patient was a responder with estimated 50-75% seizure reduction post-RNS implantation.

Conclusions: RNS has demonstrated therapeutic benefits in a pediatric patient with Dravet syndrome and drug-resistant generalized epilepsy by utilizing bilateral thalamic stimulation of the centromedian nuclei. This case further underscores the safety and efficacy of RNS as a viable treatment option for pediatric generalized epilepsy syndromes. Further research is necessary to identify optimal detection and stimulation settings specific to this population.

Funding: N/A