Abstracts

Vagus Nerve Stimulation (VNS) is a unique treatment for epilepsy. The Neurocybernetic Prothesis (NCP) was approved in the United States in 1997 as adjunctive treatment for people with partial-onset epilepsy and refractory to antiepileptic medications. A portion of those treated with VNS elect to have their NCP deactivated and/or explanted. The purpose of this analysis was to identify the clinical reasons leading to this step and to gain an insight into the issues and concerns expressed by patients and involved family members.
Retrospective chart reviews were conducted on 44 VNS implants at a tertiary care facility. Eight (18%) people were identified as having their VNS deactivated or explanted. Records were reviewed from pre-implant through post deactivation and/or explant. Demographic data were collected on age, seizure classification, seizure frequency, seizure intensity, and reported side effects of VNS. Settings of VNS were documented. Reasons for having the VNS turned off or explanted were identified. Patient and family issues were identified.
There were 2 males & 6 females comprising the 8 patients evaluated. Age ranged from 13 to 44 years. All had partial onset seizures. The VNS duration of active treatment ranged from 6 months to 4 years prior to being deactivated or explanted. Three (3/8) had significant side effects resulting in VNS intolerability. These included shortness of breath, difficulty in breathing, and dizziness. One (1/3) of these developed a late onset shortness of breath, confirmed by trials of VNS activation and deactivation. One (1/8) patient had the VNS turned off after a confirmed diagnosis of non-epileptic seizures identified on Video EEG. Five (5/8) chose to have the VNS explanted due to a lack of efficacy. Not all were able to tolerate therapeutically high stimulus frequency or cyclying settings due to side effects. Optimal stimulus ranged from 0.50 to 2.50 mA. Both patients and families expressed frustration with and consequent disappointment in VNS treatment despite pre-implant counseling concerning its risk/benefit profile. Six patients (6/8) described a strong pre-implant hope in treatment outcomes and confidence in their probable avoidance of side effect risks or treatment failure. Two (2/8) family members took similiar stands on these issues.
Further information is needed on patient and family comprehension of pre-operative VNS education in addition to causes for deactivating and/or explanting VNS. The reasons for determination to deactivate or explant a VNS were varied in this small group if patients. The results highlight the need for further study in this area. Such knowledge would assist nurses and clinicians attempting to provide anticipatory guidance to patients expressing disappointment.