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Abstract Introduction Vagal nerve stimulators (VNS) have been found to induce sleep disordered breathing and many patients will seek sleep evaluation after the development of symptoms. Snoring is a common reason patients may present. Once therapy is initiated, the lack of snoring is often used as a clinical marker for reduced apnea. Here we present the counterintuitive case of a VNS patient who had treatment-refractory obstructive sleep apnea with snoring that halted during apneic episodes. Report of case(s) A 24-year-old male, past medical history of medically refractory epilepsy w/ VNS, developmental delay with minimal verbal output, sleep apnea treated with CPAP (Continuous Positive Airway Pressure), presented for a split night polysomnogram based on reports of witnessed nocturnal apneas despite treatment with CPAP. To find new CPAP settings for worsening apnea we performed a split night polysomnogram. During the baseline diagnostic portion of the study the apnea hypopnea index was 40.9 events/hour with severe obstructive sleep apnea consisting of 12 obstructive apneas and 32 hypopneas. Respiratory events were noted to have remarkable chronicity, lasting 30 seconds every 1 min and 10 seconds. The obstructive events were also seen during wake cycles. We discovered his VNS settings were programmed for a 1 minute and 10 second OFF cycle with 30 second ON cycle, coinciding with the periodicity of his apneic events. Additionally, snoring occurred throughout the study but ceased during the hypopneas. VNS artifact was noted in the EKG lead during the 30 second periods of hypopnea in a dramatic time locked obstructive pattern, suggesting VNS induced collapse of the upper airway during VNS ON phase. Conclusion This is a report of VNS induced cessation of snoring with paradoxical worsening of hypopneas, as well as awake hypopnea events. VNS can induce sleep apnea and our study shows lack of snoring is not a reliable indicator of lack of hypopnea due to the adduction of vocal cords and resultant laryngeal collapse. We suggest that all patients with a VNS implanted device undergo a sleep study to evaluate for VNS induced OSA after implantation of VNS, and a follow up with a sleep study titration of VNS in select cases. Support (if any)
McFarlane et al. (Sat,) studied this question.