1315 Bent but Not Broken: Hypoglossal Nerve Stimulation Malfunction Caused by Severe Bending of an Intact Sensing Lead

Abstract Introduction Hypoglossal nerve stimulation (HNS) provides an alternate treatment option for CPAP intolerant or non-adherent patients with moderate to severe obstructive sleep apnea. HNS is delivered via a stimulation lead placed around the hypoglossal nerve, an implanted pulse generator, and a respiratory sensing lead placed in the chest. While there have been reports of sensing lead malfunction due to migration of lead or tip fracture, we present a unique case of sensing lead malfunction caused by severe bending of the lead with an intact tip. Report of case(s) A 64-year-old male with severe obstructive sleep apnea underwent HNS implantation due to dissatisfaction with CPAP therapy. Pre-procedure home sleep apnea test showed an AHI-4% of 37.7/hour. Post-operative course was uncomplicated. Initial waveform interrogation showed appropriate respiratory sensing. An HNS fine tune study showed only partial improvement of sleep apnea with stimulation-respiration dyssynchrony. Subsequent wave form analysis demonstrated a shark fin morphology. Waveform inversion was attempted, but an advanced fine tune study showed persistent respiratory events at different amplitude, electrode and timing settings. An awake endoscopy noted that mouth opening and neck flexion were associated with poor airway opening and use of a foam cervical collar was recommended. A home sleep apnea test at the recommended electrode settings with use of a foam cervical collar showed a treatment pAHI-4% of 40.5/hour. Due to persistently elevated AHI with aberrant respiratory sensing despite several setting adjustments, a revision of the sensing lead was pursued. Intraoperatively, the internal component of the sensing lead was noted to be severely bent with an intact lead tip. Following the sensing lead exchange, the shark fin waveform morphology resolved. A repeat home sleep apnea test showed improved treatment pAHI-4% of 13.1/hour. Conclusion A retrospective review of HNS related adverse events published in June 2024 noted that sensing lead malfunction included either lead migration or fracture. Our case highlights yet another cause of malfunction due to kinking of an intact sensing lead. It also demonstrates that HNS with non-physiologic shark-fin waveform may not be effective in improving sleep apnea despite recommended programming changes even with foam cervical collar. Support (if any)