Ansa Cervicalis Stimulation a Viable Ancillary Treatment for Some Patients with Obstructive Sleep Apnea

by Linda Kossoff •

How effective is ansa cervicalis stimulation (ACS) on pharyngeal patency during expiration in patients with obstructive sleep apnea (OSA)?

BOTTOM LINE

ACS could become a viable ancillary respiratory neurostimulation (RNS) strategy for patients with insufficient responses to hypoglossal nerve stimulation (HNS).

BACKGROUND: Hypoglossal nerve stimulation treatment can reduce pharyngeal collapsibility in patients with OSA. However, HNS non-responders often demonstrate continued pharyngeal wall collapse during stimulation. Recent evidence suggests that caudal pharyngeal traction with sternothyroid muscle contraction via ACS can also stabilize the pharynx, but underlying mechanisms have not been elucidated.

STUDY DESIGN: Prospective cohort study.

SETTING: Department of Otorhinolaryngology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Penn.

SYNOPSIS: To address their hypothesis concerning the underlying mechanisms of ACS, researchers investigated separate and combined effects of ACS and HNS on retropalatal cross-section area (CSARP) and expiratory airflow in the hypotonic airway in patients during expiration. They recruited patients with OSA scheduled to undergo drug-induced sleep endoscopy. Three RNS modalities were used: HNS alone, ACS alone, and HNS and ACS combined. Completed data were achieved with eight participants (six males/mean age 56.3 years). Subjects sustained ultrasound-guided fine-wire stimulation of the medial branch of the right hypoglossal nerve with and without transient stimulation of the branch of the ansa cervicalis nerve plexus innervating the right sternothyroid muscle during drug-induced sleep endoscopy. Results showed that neurostimulation of the sternothyroid muscle via the ansa cervicalis independently increased CSARP and expiratory airflow. Combined with HNS, ACS increased retropalatal dimensions and cross-sectional area to a greater degree than HNS alone. Findings suggest that ACS mimics the effects of tracheal traction in humans, and provide further evidence for a synergistic effect between caudal traction and ventral tongue protrusion on pharyngeal stabilization first observed in animals. Study limitations included its small sample size.

CITATION: Kent DT, Scott WC, Zealear D, et al. Ansa cervicalis stimulation increases pharyngeal patency in patients with obstructive sleep apnea. J Appl Physiol. 2021;131:487–495.