Ansa Cervicalis Stimulation: A New Direction in Neurostimulation for OSA

Abstract

BACKGROUND: 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. RESEARCH QUESTION: Does contraction of the sternothyroid muscle with ansa cervicalis stimulation (ACS), which pulls the pharynx caudally via thyroid cartilage insertions, increase maximum inspiratory airflow (V(I)max)? STUDY DESIGN AND METHODS: 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. V(I)max was assessed during flow-limited inspiration with a pneumotachometer. RESULTS: Eight participants with OSA were studied using ACS with and without HNS. Compared with baseline, the mean V(I)max increase with isolated ACS was 298%, or 473 mL/s (95% CI, 407-539). Isolated HNS increased mean V(I)max from baseline by 285%, or 260 mL/s (95% CI, 216-303). Adding ACS to HNS during flow-limited inspiration increased mean V(I)max by 151%, or 205 mL/s (95% CI, 174-236) over isolated HNS. Stimulation was significantly associated with increase in V(I)max in both experiments (P < .001). INTERPRETATION: ACS independently increased V(I)max during propofol sedation and drove further increases in V(I)max 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.