Abstracts

RATIONALE: To document, from a retrospective study, the morbidity and mortality from the use of the vagus nerve stimulator in a mixed population.
METHODS: Between 1995 and 2001, 118 patients were implanted with vagus nerve stimulators as part of the King[scquote]s/Maudsley Epilepsy Surgery programme. These patients were unsuitable for, or failed, resective surgery. This is a retrospective analysis of the mortality and morbidity
RESULTS: There was complete relief of seizures in [lt] 2%, and a 50% reduction in seizure frequency in around 34%. There were two deaths, one patient suffered SUDEP two months after implantation, before optimum control of seizures had been obtained. The other died from pneumonia 2 weeks after implantation. Two other patients suffered from pneumonia, one needing treatment with CPAP. This incidence of 2.5% is perhaps excessive following a short, relatively minor procedure. Two patients experienced cardiovascular problems. In one there was bradycardia and near asystole during the intraoperative lead test. The other, about 1 year after surgery, complained of breathlessness when the stimulator was on. He is of limited intellectual ability but it became known that there was a problem with breathing at night. Further investigation showed that in sleep desaturation occurred at five-minute intervals accompanied by bradycardia.
The remaining morbidity was minor. Two patients had local hyperaesthesia around the generator implant and one patient could not tolerate increased stimulation because of pain and discomfort. One patient with a tracheostomy as part of his treatment for a pharyngeal tumour which apperared three years after the stimulator had been inserted. He experienced stimulus related pain partly relieved by reduction in the stimulus but completely relieved by changing the metal tracheostomy tube to a plastic one. There were no infections and no lead breakages. In two patients new electrodes were sited above the original, in one case because it was claimed it caised pain and in the other case because the lead was accidentally damaged during a generator change. There was no morbidity from these electrode replacements.
CONCLUSIONS: Direct mortality from this device is less than 1%, serious morbidity is less than 3% and the cardiac problems have not had any serious sequelae. Minor problems amounted to less than 3.5%.
Disclosure: Consulting - CE Polkey receives occasional support from cyberonics for meetings but none since 1999.