1163 Central Sleep Apnea: A Possible Rare Adverse Effect of Vagus Nerve Stimulation

Abstract Introduction Vagus nerve stimulation (VNS) is a neuromodulation therapy for treatment of drug-resistant epilepsy (DRE). VNS therapy is known to affect sleep by increasing risk for obstructive sleep apnea (OSA). We present the case of a young woman with DRE and mild OSA who was found to have central sleep apnea (CSA) five years after VNS placement. Based on our literature review, there are limited case reports on this topic. Report of case(s) A 22-year-old female with a history of Tuberous Sclerosis and DRE, couple months’ status post-VNS placement presented for snoring and gasping arousals. She underwent Polysomnography (PSG), which documented mild OSA, with an apnea-hypopnea index (AHI) of 8.6 and associated oxygen desaturation nadir of 82%. Average transcutaneous CO2 (TcCO2) monitoring during supine wakefulness was 43.1 mmHg and during sleep was 44.2 mmHg respectively. She had a titration PSG, which noted that a Continuous Positive Airway Pressure (CPAP) setting of 6 cm of water was effective in treating her OSA. CSA was not observed in either of those studies. Five years later, the patient returned for a routine follow-up. Her home CPAP data review showed that despite a four-hour compliance of 90%, the average CPAP-generated AHI was 14.9. Titration PSG was performed, which showed frequent obstructive and central apneas. Bilevel PAP in ST mode was tested at 15/10 cm of water with a respiratory rate of 10 per minute, which helped apneas. However, obstructive and central hypopneas persisted in this setting. Additionally, global hypercarbia was observed with an average TcCO2 value of 51.9 mmHg during supine wakefulness and 60mmHg (412 minutes > 55mmHg) during sleep, respectively. An MRI two years prior to this titration PSG showed no structural cause for the central apnea. She has never been on opioids and her BMI (30.5) has remained largely unchanged in the past five years. She is planned to have a follow up for further evaluation including changes in VNS settings and a retitration PSG study. Conclusion CSA remains an unexplored possible adverse effect of VNS implantation. Further investigations are needed to establish a direct correlation between VNS implantation and CSA. Support (if any) none