Ansa Cervicalis Stimulation: A New Direction in Neurostimulation for OSA

Abstract

Hypoglossal nerve stimulation (HNS) is an alternative treatment option for patients with OSA unable to tolerate positive airway pressure but implant criteria limit treatment candidacy. Previous research indicates that caudal tracheal traction plays an important role in stabilizing upper airway patency. Does contraction of the sternothyroid muscle with ansa cervicalis stimulation (ACS), which pulls the pharynx caudally via thyroid cartilage insertions, increase maximum inspiratory airflow (VImax)? Hook-wire percutaneous electrodes were used to stimulate the medial branch of the right hypoglossal nerve and right branch of the ansa cervicalis innervating the sternothyroid muscle during propofol sedation. VImax was assessed during flow-limited inspiration with a pneumotachometer. Eight participants with OSA were studied using ACS with and without HNS. Compared with baseline, the mean VImax increase with isolated ACS was 298%, or 473mL/s (95%CI, 407-539). Isolated HNS increased mean VImax from baseline by 285%, or 260mL/s (95%CI, 216-303). Adding ACS to HNS during flow-limited inspiration increased mean VImax by 151%, or 205mL/s (95%CI, 174-236) over isolated HNS. Stimulation was significantly associated with increase in VImax in both experiments (P< .001). ACS independently increased VImax during propofol sedation and drove further increases in VImax when combined with HNS. The branch of the ansa cervicalis innervating the sternothyroid muscle is easily accessed. Confirmation of the ansa cervicalis as a viable neurostimulation target may enable caudal pharyngeal traction as a novel respiratory neurostimulation strategy for treating OSA.