Challenges with Neural Anomalies in Hypoglossal Nerve Stimulator Implantation

Abstract

Hypoglossal nerve stimulation (HGNS) is an FDA-cleared therapy for obstructive sleep apnea (OSA) in patients who cannot or are unable to tolerate contentious positive airway pressure (CPAP) therapy. However, underlying neural anomalies may impair surgical efficacy and require intraoperative adaptability. We present 2 cases of HGNS in patients with preexisting neurologic conditions affecting nerve morphology. Case 1 involves a 66-year-old woman with OSA (REI 52.5) and neurofibromatosis (NF). Despite normal tongue motion and favorable drug-induced sleep endoscopy (DISE), intraoperative findings revealed diffuse enlargement of the hypoglossal nerve. The nerve exhibited weak and inconsistent stimulation responses, and the cuff could not be placed effectively. The procedure was aborted. Postoperative MRI confirmed diffuse left-sided hypoglossal nerve thickening consistent with a plexiform neurofibroma. Case 2 features a 64-year-old man with OSA (AHI 41.3) and chronic inflammatory demyelinating polyneuropathy (CIDP). Intraoperatively, the hypoglossal nerve was enlarged, firm, and lacked identifiable branches. Mixed stimulation patterns prevented functional cuff placement. A contralateral approach was pursued with successful implantation and device activation. These cases highlight challenges in HGNS when neural anomalies—such as those from NF or CIDP—alter nerve structure or function. Neurofibromas can diffusely infiltrate cranial nerves, complicating stimulation, while CIDP causes patchy demyelination and conduction variability. Preoperative imaging, including high-resolution T2-weighted MRI, is essential to assess nerve morphology and plan surgical approaches. Surgeons must be prepared for intraoperative variability, including the potential need for contralateral dissection. Anomalies of the hypoglossal nerve can compromise HGNS success. Preoperative identification of underlying neuropathies and adaptable intraoperative planning are critical for optimizing outcomes in complex patients.