Vagus Nerve Stimulation for Treatment-Resistant Depression: a Case Series of Clinical Symptoms Associated with the End of Service Period.

BACKGROUND: This work describes the clinical symptoms associated with end of service (EOS) of the batteries of vagus nerve stimulation (VNS) generators in treatment-resistant depression (TRD). Because neurostimulator software may not provide reliable information on battery depletion, careful monitoring of clinical symptoms during the EOS period is an important concern in the follow-up of TRD patients treated with VNS therapy. METHODS: Twenty-six (26) patients were implanted and followed at the Centre Hospitalier de l'Université de Montréal. Fourteen (14) patients required battery replacement and we retrieved chart data up to 3 months before generator battery replacement. RESULTS: Our study demonstrated there might be a decrease or increase in VNS associated physical side effects, and possibly an increase in depressive symptoms during EOS. LIMITATIONS: Our observations are limited by the retrospective nature of this small case series, and larger prospective studies evaluating both VNS side effects and depressive symptoms are therefore needed to further validate those findings. CONCLUSION: Our study is the first to examine clinical symptoms associated with EOS of the batteries of VNS in TRD.