The specific branches leading to the genioglossus muscle: three-dimensional localisation using skin reference points

Influence of Body Posture and Apnea Severity on the Tone and Elasticity of Upper Airway Muscles in Awake Patients With Obstructive Sleep Apnea: A Cross-Sectional Study

OBJECTIVE

The purpose of this study was to compare the effect of body posture and apnea severity on the tone, stiffness, and elasticity of upper airway muscles in awake patients with obstructive sleep apnea syndrome (OSAS).

METHODS

Eighty adult patients with OSAS from the Sleep Laboratory of the Bitlis State Hospital between April and December 2021 were included in the study. The tone, stiffness, and elasticity of the genioglossus and accessory muscles (sternocleidomastoid, masseter) were measured while the patients were awake, sitting upright, and in supine posture. According to polysomnography results and the Apnea-Hypopnea Index, patients were classified as mild, moderate, or severe OSAS.

RESULTS

There were 56 male (70%) and 24 female (30%) patients (age 45.0 ± 11.0 years). Tone of genioglossus, masseter, and sternocleidomastoid muscles were higher in supine than in sitting posture (all P < .05). There was no difference in elasticity scores of the bilateral genioglossus muscle in sitting and supine posture (P > .05). The elasticity scores of the sternocleidomastoid and masseter muscles were higher in sitting (all P < .05). An interaction effect of postural change and apnea severity was observed on stiffness scores of the genioglossus muscle (P < .05).

CONCLUSION

Results showed that the genioglossus muscle and accessory muscles take on the inspiratory load that develops with postural strain, regardless of the severity of apnea, in awake patients with OSAS. For participants measured in this study, accessory muscles supported respiration by increasing their elasticity.

Ultrasound Localization and Percutaneous Electrical Stimulation of the Hypoglossal Nerve and Ansa Cervicalis

OBJECTIVE

Hypoglossal nerve stimulation for obstructive sleep apnea (OSA) can be effective for appropriately selected patients, but current patient selection criteria are complex and still result in a proportion of nonresponders. Ansa cervicalis stimulation of the infrahyoid cervical strap muscles has recently been proposed as a new form of respiratory neurostimulation (RNS) therapy for OSA treatment. We hypothesized that percutaneous stimulation of both nerves in humans with temporary electrodes would make testing of the physiologic response to different RNS strategies possible.

STUDY DESIGN

Nonrandomized acute physiology study.

SETTING

Tertiary care hospital.

METHODS

Fifteen participants with OSA underwent ultrasonography and placement of percutaneous electrodes proximal to the medial division of the hypoglossal nerve and the branch of the ansa cervicalis innervating the sternothyroid muscle (ACST). Procedural success was documented in each participant, as were any failures or procedural complication.

RESULTS

The hypoglossal nerve was successfully localized in 15 of 15 (100%) participants and successfully stimulated in 13 of 15 (86.7%). The ACST was successfully localized in 15 of 15 (100%) participants and successfully stimulated in 14 of 15 (93.3%). Stimulation failure of the hypoglossal nerve was due to suboptimal electrode placement in 1 participant and electrode displacement in the other 2 cases. No complications occurred.

CONCLUSIONS

The hypoglossal nerve and ACST can be safely stimulated via percutaneous electrode placement. Larger trials of percutaneous stimulation may help to identify responders to different RNS therapies for OSA with temporary or permanent percutaneous electrodes. Techniques for electrode design, nerve localization, and electrode placement are described.