Abstracts

Rationale: Vagus Nerve Stimulation Therapy(VNS) gained EU licence in 1994 as an adjunctive therapy for treatment of refractory epilepsy where epilepsy surgery may not be a viable option and/or antiepileptic medications may have failed or had unacceptable side effects. The additional use of magnet mode upon seizure detection has shown benefits in aborting or reducing severity of seizures. However, for those patients who do not experience auras, or are unable to self-activate the magnet or during sleep, the full efficacy of therapy may not be seen. Automatic stimulation by use of seizure detection algorithm based on ictal tachycardia was incorportated into Aspire SR 106™ model, licensed in 2014 following an European muliticentre trial(E36)Methods: Children implanted with the new Aspire SR device were followed prospectively from August 2014 at Great Ormond Street Hospital for Children, (a tertiary referral centre in UK). Initially only children with confirmed ictal tachycardia on video telemetry were implanted with the new device. ECG was performed pre-implantation to enable accurate placement of the device. The seizure detection algorithm for automatic stimulation was set to 40 % in all patients. Auto-stimulation was switched on with parental agreement. Patients were monitored at monthly intervals at ramping-up. Data were collected regarding seizure frequency, duration, severity, and postictal recovery period, side-effects and quality of life.Results: Currently (June 2015), 8 Aspire SR ™ devices have been implanted in paediatric patients; of which six were new implants and two were battery replacements. (There were six males and two females, with an age range of 6-16 years). Seizure types were focal (2), myoclonic (1), myoclonic astatic (1), generalised (2), multi-focal (1) and 1 child with Lennox –Gastaut syndrome. Aetiologies were diverse: acquired (2), genetic (4), structural (1) and cryptogenic (1). All children had learning difficulties. Obtaining accurate pre-implantation clinic ECG was challenging in this patient group. In theatre validation of heart beat sensitivity proved fully adequate. Preliminary results show >50% seizure reduction noted in 2 children (at 2-7 months), both are seizure free; one child has a reduction but not as great as 50% and 3 children have yet to show a response. Adverse effects included self-resolving cough on initial ramping up of the device (3), prolonged nocturnal hiccups (1) transient chest pain when auto-stimulation was first switched on (1).Conclusions: In this preliminary study, early results suggest that cardiac based seizure detection by Aspire SR VNS therapy may lead to good early seizure reduction. The greater battery longevity with this device is also advantageous. Pre-theatre ECG is not needed. Transient side effects only have been encountered. While these preliminary results are encouraging, longer-term follow up and a larger cohort of patients would be required before definitive conclusions can be made.