Hypoglossal nerve stimulation - Optimizing its therapeutic potential in obstructive sleep apnea (Aug 2014, Journal of Neurological Sciences)
Obstructive sleep apnea is characterized by recurrent periods of upper airway obstruction (apneas and hypopneas) during sleep, leading to nocturnal hypercapnia, repeated oxyhemoglobin desaturations and arousals. It is a highly prevalent condition affecting 4 to 24% of men and 2 to 9% of women, and well over 50% of obese individuals. Obstructive sleep apnea is a major cause of morbidity and mortality in Western society and contributes significantly to the development and progression of neurocognitive, metabolic, cardiovascular, and oncologic diseases.
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Introduction: Obstructive sleep apnea (OSA) is a Residual Effect of THN Hypoglossal Stimulation in Obstructive Sleep Apnea. A disease modifying therapy. (Jun 2013, American Journal of Respiratory and
Background: Obstructive Sleep Apnea is a debilitating chronic sleep-related condition where pharyngeal closure leads to temporary breathing cessation inducing falls in oxygen saturation, sympathetic surges and sleep fragmentation. The disease is efficiently treated with continuous positive airway pressure applied through the nose, a symptomatic therapy without residual effect, but the devices used are cumbersome and many patients abandon or refuse the treatment. Hypoglossal nerve stimulation is emerging as an alternative therapy that could have disease modifying properties. Hypothesis: Long-term treatment with Hypoglossal Targeted Neurostimulation could show residual effects through changes in tongue muscle properties or coordination and result in at least temporary abolition of obstructive sleep apnea. Methods: We studied 10 patients with moderate to severe obstructive sleep apnea non compliant with CPAP, after one year THN therapy. Patients had polysomnographic recording with active THN therapy and with THN turned off. Results: THN resulted in significant improvements in the Apnea-Hypopnea index, the 4%Desaturation Index and sleep fragmentation with respect to the diagnostic results at 3 and 12 months therapy. Turning off the stimulation for one night produced no changes in these results: patients remained significantly less affected by sleep apnea than before treatment. Conclusions: THN appears not only as a symptomatic treatment but may have disease modifying properties with residual effects, paving the way to some form of intermittent treatment.
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Targeted Hypoglossal Neurostimulation for Obstructive Sleep Apnea. A 1 year pilot Study. (Feb 2013, European Respiratory Journal)
Continuous positive airway pressure (CPAP) is an effective but cumbersome treatment for obstructive sleep apnoea (OSA). Noncompliant patients need alternative therapies. We studied a tongue neurostimulation approach: targeted hypoglossal neurostimulation (THN) therapy with the aura6000™ System. A multi-contact electrode positioned around the main trunk of the twelfth nerve connected to an implanted pulse generator stimulates segments of the nerve, activating dilator muscles. The primary objective was to improve the polysomnographically determined apnoea/hypopnoea index (AHI) at 3 months, and maintain the improvement after 12 months of treatment. 13 out of 14 operated patients were successfully implanted. At 12 months, the AHI decreased from 45±18 to 21±17, a 53% reduction (p<0.001). The 4% oxygen desaturation index fell from 29±20 to 15±16 and the arousal index from 37±13 to 25±14, both p<0.001. The Epworth sleepiness scale decreased from 11±7 to 8±4 (p=0.09). THN was neither painful nor awakened patients, who all complied with therapy. There were two transient tongue paresis. The present study represents the longest study of any hypoglossal neurostimulation reported to date. We conclude that THN is safe and effective to treat OSA in patients not compliant with CPAP.
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Tongue Anatomy and Physiology, the Scientific Basis for a Novel Targeted Neurostimulation System Designed for the Treatment of Obstructive Sleep Apnea (Jul 2013, Journal of Neuromodulation)
chronic condition that affects millions adults. The effective standard treatment is positive airway pressure (PAP). However, approximately half of the patients that are prescribed PAP are unable or unwilling to comply with this therapy. Untreated OSA ultimately leads to very serious comorbidities. An alternative therapy for this patient population, therefore, is desirable. Hypoglossal nerve (HGN) stimulation is under investigation by multiple groups as a possible alternative therapy for OSA. Objective: To understand the underlying mechanisms of actions related to HGN stimulation, and the implication of this knowledge for specifying and designing a neurostimulation system for the treatment of OSA. Results: Loss of lingual and pharyngeal tone within a narrow airway is the primary mechanism for OSA. Posterior and anterior tongues are different in their anatomy and physiology. Muscle fibers in the posterior tongue are predominantly fatigue resistant that are responsible for the long sustained tonic activities required for maintaining the tongue's position and preventing its mass from falling into the retroglossal airway. The human tongue is a muscular hydrostat and hence would benefit from a sophisticated HGN stimulation system that is capable of achieving a concerted spatio-temporal interplay of multiple lingual muscles, including retrusors. Conclusion: Targeted neurostimulation of the proximal HGN presents as a viable system approach that is far more versatile and physiologic and quite different than prior systems.
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