Abstracts

Rationale: VNS is a treatment option in patients with refractory epilepsy unsuitable for other surgical options. VNS helps in intractable cases with an average decrease in seizure frequency by 40%. It involves an operation to implant under the skin a generator with coils wrapped around the left Vagus. VNS is well tolerated and safe though there have been cases reported of bradycardia occurring intraoperatively and clinically. Parasympathetic hyper stimulation of the right Vagus predisposes to bradycardia. The left Vagus when hyper stimulated predisposes to atrioventricular (AV) blocks. There has been no cases that we are aware of reporting AV blocks post VNS. We report a case of iatrogenic ventricular asystole presenting as drop attacks following VNS which initially was misdiagnosed as seizure worsening. Methods: A 55 year old man with intellectual disability & treatment resistant intractable epilepsy (generalised seizures including drop attacks) had a VNS fitted. There were no intraoperative complications. The VNS workup did not reveal any pre cardiac problems. His seizures improved. Two years later there was an idiopathic increase in drop attacks which was, given his past seizure history considered to be seizure worsening. There was no improvement to anti-epileptic medication and VNS titration leading to a review of his cardiac status. Results: A 24hr ECG showed recurrent episodes of ventricular standstills, pauses and runs of complete heart block corresponding with VNS stimulation. No other cause could be found to explain this occurrence. VNS was turned off. Subsequent ECG was unremarkable. Two months later all forms of his epilepsy worsened prompting a patient choice of switching on the VNS under 24hr ECG monitoring. The ECG after switch on showed continued P wave activities but runs of ventricular asystole after VNS stimulation. The longest asystole was 9.79 seconds. This led to the VNS being turned off again. Conclusions: VNS is considered a safe option in epilepsy management. Unfortunately it can cause side effects of iatrogenic asystole and misdiagnosis of seizure worsening. Awareness of this rare but late onset, life threatening side effect of VNS is important.