Abstracts

Rationale: Patients with myoclonic astatic epilepsy (MAE) typically have medically refractory epilepsy. This chart review study investigates the efficacy of vagus nerve stimulation (VNS) in the treatment of MAE.Methods: We retrospectively reviewed the medical records of children with MAE who received VNS for at least 12 months. The following clinical features were assessed: age of onset of epilepsy, seizure type and frequency, number of previous antiepileptic medications (AEDs), age at VNS implant, number of AEDs at implant, and response to treatment.Results: Four children (3 boys, 1 girl) were followed for 12 months after VNS implantation. The median age at onset of epilepsy was 26 months (range 9-72 months). The median age at implantation of VNS was 5.3 years (range 4.2-8.4 years). The median number of previous AEDs was 5.5 (range 5-8). Current antiepileptic medications included Valproate (3/4), Felbamate (1/4), Zonisamide (1/4), Levetiracetam (1/4), Clonazepam (1/4). Three children were on 2 AEDs and 1 child was on 3 AEDs at the time of VNS implant. Seizure types and frequency per month at baseline were as follows: atypical absence - 3 patients had too many to count (TMTC), and 1 was controlled on Valproate; atonic- 1 patient with 8, 1 with 60, 1 with TMTC, and 1 controlled on Levetiracetam; myoclonic- 1 patient with 0, and 3 with TMTC; and GTCs - 1 with 1, 1 with 90, 1 with 4, and 1 with 0. After 3 months of VNS therapy, 2 patients had no change in seizure frequency or type; data was missing for 1 patient. The patient who had only myoclonic seizures had a ≥90% reduction in seizures. After 12 months of VNS therapy there was a ≥90% reduction in atypical absence and myoclonic seizures in three patients, a 100% reduction in atonic seizures in three patients, a ≥90% reduction in GTCs in 2 patients and 100% reduction in GTCs in one patient. All four patients reduced their AED dosages during this study period; no new AEDs were added. All patients tolerated VNS without adverse effects.Conclusions: Three patients with MAE with refractory seizures had a total cessation of atonic seizures and a ≥90% reduction in atypical absence and myoclonic seizures 12 months after VNS implantation. Furthermore, VNS was effective in reducing GTCs by at least 90%. These results suggest that VNS therapy is effective in this refractory syndrome. Further study of VNS in the treatment of MAE is warranted. (Funded by Department of Pediatrics, Section of Child Neurology, Baylor College of Medicine, Houston, TX)