Review of genioglossus muscle electrical stimulation efectiveness for the treatment of obstructive sleep apnea-hipopnea (OSAHS)

Abstract

In 1978 Remmens determined that genioglossus (GG) is the main pharyngeal dilator muscle. His study showed an increase of neuromuscular activity of GG in the process of overcoming the obstruction of the upper airway. Accordingly, electrical stimulation (ES) of GG appears to be a suitable treatment for OSAH. However, recent studies do not support it due to the GG is a phasic muscle, which is more strong in untreated OSAH patients. We have searched articles in Medline, Embase and Cochrane Library. In favour: a study of Oliven showed a decrease of the critical pressure intrapharyngeal after applying ES in patients with OSAH. There was no difference between the electrodes implanted in the hypoglossal nerve and into the GG muscle. Later, Ludwing showed that the ES transcutaneous is also effective for toning GG. His study obtained an increase in the volume of GG (3D sonography measurement). There was no difference between the large electrode placed on the mouth’s floor and multi-point electrodes. Against: fiber compositions of the pharyngeal muscles analysis performed by Wouldson showed that GG is a phasic muscle (type II fibers, which are strong and fatigables). Since maintaining the patency of upper airway is a typical function of type I fibers (which are slightly stronger and tireless) it seems that GG ES is not suitable. A study of Berry found that the GG neuromuscular activity in untreated OSAH patients was higher than in healthy subjects. GG weakness is not the cause of upper airway obstruction. We can say that GG acts to compensate the upper airway blockage caused by postural muscles weakness (as tensor of the soft palate muscle). The most effective ES in OSAHS should impact on the postural muscles. The authors thank Hospital General de Catalunya.