Cross-linked innervation of the hypoglossal nerve in patients with upper airway stimulation

Introduction:

The innervation of the extrinsic and intrinsic tongue muscles by the hypoglossal nerve (HN) is very complex. Upper airway stimulation of the N.XII in patients with obstructive sleep apnea (OSA) is a treatment option, which helps to keep the pharyngeal airway open during sleep. The aim of the study was to figure out if a cross-over innervation of the N. XII is a predictive factor for therapy success.

Methods:

A total of 20 patients were enrolled from January 2017 to October 2017, who received a stimulation system of HN (Inspire Medical Systems, USA). Intraoperatively, a 4-channel neuromonitoring (NIM 3.0, Medtronic) was placed in the tongue on both sides – 2 electrodes per side -. This is for the detection of EMG singals were detected to verify cross innervations. Furthermore, during activation of the system, different tongue motions were recorded and compared with intraoperative EMG signals.

Results:

Ten patients showed ipsilateral innervations due to the EMG signals intraoperatively and 10 patients had bilateral innervations. When compared with tongue movement postoperatively, patients with bilateral innervations were more likely to have an opening at the level of the soft palate compared to ispilateral innervations. However, this result was not reflected in the relative reduction in the apnea-hypopnea index (AHI) (% AHI reduction ipsi.: 86%, bilat.: 85%).

Conclusion:

The study showed that 50% of patients have a cross innervation of the HN on the contralateral side. This seems to be associated with better opening of the pharynx at the level of the soft palate, but does not appear to be reflected in clinical outcome.

Publication History

Publication Date:
18 April 2018 (online)