Treating Obstructive Sleep Apnea With Hypoglossal Nerve Stimulation

Arie Oliven


Curr Opin Pulm Med. 2011;17(6):419-424. 

In This Article

Experimental Animal Models

Functional electrical stimulation of striated muscles provides an important tool to assess their mechanical effect and has been largely employed since the early 1980s to assess the effects of pharyngeal dilator muscles on the upper airway. Virtually all animal studies have confirmed that stimulation of dilator muscles enlarges and stabilizes the pharynx. Results obtained in anesthetized animals need to be interpreted cautiously when applied to humans, as upper airway anatomy differs among mammals in several important aspects, and none of the animal models studied are prone to developing sleep apnea. Keeping these reservations in mind, the following are some of the animal studies that provided findings relevant to therapeutic dilator muscle stimulation: stimulation of hypoglossus nerve fibers that innervate the tongue appears to produce equal or larger mechanical effects compared to other cranial nerves that innervate pharyngeal and palatal muscles;[14] stimulation of the whole hypoglossus nerve, which co-activates both protrusor and retractor muscles of the tongue, enlarges the pharynx to a similar degree as selective stimulation of the medial branch of the hypoglossus nerve, which preferentially contracts tongue protrusors;[15] unilateral stimulation of the hypoglossus nerve produces responses comparable to bilateral stimulation in rabbits, even with sub-maximal stimulation intensities;[16] direct stimulation of the genioglossus muscle produces similar results to those obtained by stimulation of the hypoglossus nerve, suggesting that stimulation of the genioglossus muscle can predict responses to hypoglossus nerve stimulation;[17] comparison of the effects of several dilator muscles indicates that the mechanical response to genioglossus muscle stimulation is significantly larger than that of stimulation of other muscles, and is independent of head position[18] genioglossus muscle contraction can also ameliorate partial or complete pharyngeal obstruction;[19] in dogs implanted with hypoglossus nerve stimulators (HGNSs), mechanical efficacy is maintained despite chronic excitation over months without any sign of damage to the hypoglossus nerve;[20] and finally, specially designed electrodes may enable selective stimulation of specific fiber bundles within the hypoglossus nerve.[21]


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