Parameters affecting pharyngeal response to genioglossus stimulation in sleep apnoea (original) (raw)
Related papers
Surgical and Radiologic Anatomy, 2016
Purpose To determine the ideal implantation site for selective tongue neurostimulation in obstructive sleep apnea, anatomy of the distal branching of the hypoglossal nerve (HGN) was revisited. Methods The HGN distal course and intramuscular distribution to the tongue muscles were studied in 17 embalmed and 5 fresh heads (age 60-98, BMI 20-35). Medial branches supplying selectively the genioglossus (GG) muscle were identified. Then, the distinct bundles entering the oblique (GGo) and horizontal (GGh) parts of the GG were located. Morphometric data were compared to similar measurements made on MRI sections from 12 patients (age 43-71, BMI 18-47). Results The key facts relevant to optimize stimulation and electrode design are the following: the mean width of both GG muscles in embalmed and fresh cadavers was 20.7 ± 2.9 and 21.4 ± 5 mm, respectively; it is significantly (p \ 0.05) superior to the MRI value of 18.26 ± 2.0 mm. Selective nervous branches for GGh and GGo were located at 52 ± 8% of hyoid bone-mandibular symphysis distance and at 5.8 ± 1.1 mm from the inferior border of the GG muscle. The surface of stimulation is a 4.4 ± 1.1 9 6.9 ± 3.8 mm ellipse. Conclusions According to our observations, the optimal selective or supra-selective stimulation of the tongue protractor muscles can be performed on the lateral surface of the GG at roughly equal distance between the mandibular symphysis and the hyoid bone, at a depth of about 0.6 cm above the GG lower border.
American Journal of Orthodontics and Dentofacial Orthopedics, 1996
Knowledge of how dental appliances alter upper airway muscle activity when they are used for the treatment of snoring and/or obstructive sleep apnea (OSA) is very limited. The purpose of this study was to define the effect of a tongue retaining device (TRD) on awake genioglossus (GG) muscle activity in 10 adult subjects with OSA and in 6 age and body mass index (BMI) matched symptom-free control subjects. The TRD is a custom-made appliance designed to allow the tongue to remain in a forward position between the anterior teeth by holding the tongue in an anterior bulb with negative pressure, during sleep. This pulls the tongue forward to enlarge the volume of the upper airway and to reduce upper airway resistance. In this study, two customized TRDs were used for each subject. The TRD-A did not have an anterior bulb but incorporated lingual surface electrodes to record the GG electromyographic (EMG) activity. The TRD-B contained an anterior bulb and two similar electrodes. The GG EMG activity was also recorded while patients used the TRD-B but were instructed to keep their tongue at rest outside the anterior bulb; this condition is hereafter referred to as TRD-X. The GG EMG activity and nasal airflow were simultaneously recorded while subjects used these customized TRDs during spontaneous awake breathing in both the upright and supine position. The following results were obtained and were consistent whether subjects were in the upright or the supine position. The GG EMG activity was greater with the TRD-B than with the TRD-A in control subjects (p < 0.05), whereas the GG EMG activity was less with the TRD-B than with the TRD-A in subjects with OSA (p < 0.01). Furthermore, there was no significant difference between the GG EMG activity of the TRD-A and the TRD-X in control subjects, whereas there was less activity with the TRD-X than with the TRD-A in subjects with OSA (p < 0.05). On the basis of these findings, it was concluded that the TRD has different effects on the awake GG muscle activity in control subjects and patients with OSA. The resultant change in the anatomic configuration of the upper airway caused by the TRD may be important in the treatment of OSA because such a change may alleviate the impaired upper airway function. (Am J Orthod
Pharyngeal Pressure and Flow Effects on Genioglossus Activation in Normal Subjects
American Journal of Respiratory and Critical Care Medicine, 2002
Pharyngeal dilator muscles are clearly important in the pathogenesis of obstructive sleep apnea syndrome. Substantial data support the role of local mechanisms in mediating pharyngeal dilator muscle activation in normal humans during wakefulness. Using a recently reported iron lung ventilation model, we sought to determine the stimuli modulating genioglossus activity, dissociating the influences of pharyngeal negative pressure, from inspiratory airflow, resistance, and CO 2. To achieve this aim, we used two gas densities at several levels of end-tidal CO 2 and a number of intrapharyngeal negative pressures. The correlations between genioglossus electromyography (GGEMG) and epiglottic pressure across a breath remained robust under all conditions (R values range from 0.71 Ϯ 0.07 to 0.83 Ϯ 0.05). In addition, there was no significant change in the slope of this relationship despite variable gas density or CO 2 levels. Although flow also showed strong correlations with genioglossus activity, there was a significant change in the slope of the GGEMG/flow relationship with altered gas density. For the group averages across conditions (between breath analysis), the correlation with GGEMG was robust for negative pressure (R 2 ϭ 0.98) and less strong for other variables such as flow and resistance. These data suggest that independent of central pattern generator activity, intrapharyngeal negative pressure itself modulates genioglossus activity both within breaths and between breaths.
Dilation of the oropharynx via selective stimulation of the hypoglossal nerve
Journal of Neural Engineering, 2005
The functional effects of selective hypoglossal nerve (HG) stimulation with a multi-contact peripheral nerve electrode were assessed using images of the upper airways and the tongue in anesthetized beagles. A biphasic pulse train of 50 Hz frequency and 2 s duration was applied through each one of the tripolar contact sets of the nerve electrode while the pharyngeal images were acquired into a computer. The stimulation current was limited to 20% above the activation threshold for maximum selectivity. The images showed that various contact sets could generate several different activation patterns of the tongue muscles resulting in medial and/or lateral dilation and closing of the airways at the tongue root. Some of these patterns translated into an increase in the oropharyngeal size while others did not have any effect. The pharyngeal sizes were not statistically different during stimulation either between the two different positions of the head (30 • and 60 • ), or when the lateral contacts were compared with the medial ones. The contacts that had the least effect generated an average of 53 ± 15% pharyngeal dilation relative to the best contacts, indicating that the results are marginally sensitive to the contact position around the HG nerve trunk. These results suggest that selective HG nerve stimulation can be a useful technique to produce multiple tongue activation patterns that can dilate the pharynx. This may in turn increase the size of the patient population who can benefit from HG nerve stimulation as a treatment method for obstructive sleep apnea.
Interacting effects of genioglossus stimulation and mandibular advancement in sleep apnea
Journal of Applied Physiology, 2009
Both mandibular advancement (MA) and stimulation of the genioglossus (GG) have been shown to improve upper airway patency, but neither one achieves the effect of continuous positive airway pressure (CPAP) treatment. In the present study we assessed the combined effect of MA and GG stimulation on the relaxed pharynx in patients with obstructive sleep apnea (OSA). We evaluated responses of upper airway pressure-flow relationships and endoscopically determined pharyngeal cross-sectional area to MA and electrical stimulation of the GG in 14 propofol-anesthetized OSA patients. Measurements were undertaken at multiple levels of CPAP, enabling calculation of the critical closing pressure (Pcrit), upstream resistance (Rus), and pharyngeal compliance. GG stimulation, MA, and the combination of both shifted the pressure:flow relationships toward higher flow levels, resulting in progressively lower Pcrit (from baseline of 2.9 ± 2.2 to 0.9 ± 2.5, −1.4 ± 2.9, and −4.2 ± 3.3 cmH2O, respectively),...
Genioglossal But Not Palatal Muscle Activity Relates Closely to Pharyngeal Pressure
American Journal of Respiratory and Critical Care Medicine, 2000
The stimuli controlling pharyngeal dilator muscles are poorly defined. Local mechanoreceptors are a leading possibility. To address this, we assessed the relationship between two dilator muscle electromyograms (EMGs, i.e., genioglossus [GG-an inspiratory phasic muscle], tensor palatini [TP-a tonically active muscle]) and potential stimuli (i.e., epiglottic pressure [Pepi], airflow [ ], and pharyngeal resistance [Rpha]). Fifteen normal subjects were studied, during wakefulness and stable non-rapid eye movement (NREM) sleep. The GGEMG and TPEMG were assessed during basal breathing and during inspiratory resistive loading (four loads, done in triplicate), while quantifying Pepi and choanal pressures (Pcho, Millar catheters) plus. There was a strong correlation between Pepi and GGEMG during wakefulness in most subjects (9 of 15 had absolute R Ͼ 0.7 [p Ͻ 0.05], group mean R ϭ Ϫ 0.62, p Ͻ 0.05). These correlations were less robust during NREM sleep (8 of 15 absolute R Ͼ 0.6 [p Ͻ 0.05], group mean R ϭ Ϫ 0.39, ns). The slope of the Pepi versus GGEMG relationship was greater during wakefulness than sleep (Ϫ 0.67 versus Ϫ 0.39% max/ cm H 2 O, p Ͻ 0.05). No significant correlations were observed between TPEMG and any of the measured potential stimuli. We conclude that intrapharyngeal pressure may modulate genioglossus activity during wakefulness, with a fall in muscle responsiveness during sleep. The activity of the TP was not clearly influenced by any measured local stimulus either awake or asleep.
The Effect of Neuromuscular Stimulation of the Genioglossus on the Hypopharyngeal Airway
The Laryngoscope, 2002
Objectives To determine the effects of neuromuscular stimulation (NS) of the genioglossus muscle on hypopharyngeal airway size.Study Design Fourteen consecutively recruited healthy volunteers underwent percutaneous electrical NS of the genioglossus muscle.Methods Bipolar hooked wires were inserted percutaneously into the genioglossus muscle and used for NS. The anterior–posterior diameter of the hypopharynx was measured at the level of the superior edge of the epiglottis at baseline and during NS from recorded video endoscopic examinations.Results NS of the genioglossus muscle resulted in a significant increase in the diameter of the hypopharyngeal airway (P = .002) compared with baseline, ranging from a 33% to 284% increase in airway diameter. Three of the 14 patients demonstrated modest decreases in airway diameter, likely the result of faulty electrode placement in surrounding tongue retrusive muscles.Conclusions NS of the genioglossus muscle was effective in increasing the hypop...
Short-Term Potentiation in the Control of Pharyngeal Muscles in Obstructive Apnea Patients
Sleep, 2014
Study Objectives: To determine if activation of the genioglossus (GG) muscle during obstructive apnea events involves short-term potentiation (STP) and is followed by sustained activation beyond the obstructive phase (after-discharge). Design: Physiological study. Setting: Sleep laboratory in a tertiary hospital. Participants: Twenty-one patients with obstructive apnea. Interventions: Polysomnography on continuous positive airway pressure (CPAP) with measurement of genioglossus activity. Brief dial-downs of CPAP to induce obstructive events. Measurements and Results: Peak, phasic, and tonic genioglossus activities were measured breath-by-breath before, during, and following threebreath obstructions. Tonic but not phasic activity increased immediately following the first obstructed breath (4.9 ± 1.6 versus 3.6 ± 1.2 %GG MAX ; P = 0.01) under conditions where stimuli to genioglossus activation were likely constant, strongly implicating STP in mediating recruitment of tonic activity. Both phasic and tonic activities declined slowly after relief of obstruction (after-discharge). Decay time constants were systematically shorter for phasic than for tonic activity (7.5 ± 3.8 versus 18.1 ± 8.4 sec; P < 0.001). Decay time-constant of peak activity correlated with tonic, but not phasic, recruitment. Cortical arousal near the end of obstruction resulted in a lower after-discharge (P < 0.01). Contribution of tonic activity to the increase in peak activity (6-65%Peak), as well as the decay constant (6-30 sec), varied considerably among patients. Conclusions: Short-term potentiation contributes to recruitment of the genioglossus during obstructive episodes and results in sustained tonic activity beyond the obstructive phase, thereby potentially preventing recurrence of obstruction. Wide response differences among subjects suggest that this mechanism may contribute to severity of the disorder. The after-discharge is inhibited following cortical arousal, potentially explaining arousals' destabilizing effect.
Tongue mechanical characteristics and genioglossus muscle EMG in obstructive sleep apnoea patients
Respiratory Physiology & Neurobiology, 2004
The increased genioglossus muscle (GGm) activity seen in obstructive sleep apnoea syndrome (OSAS) may lead to increased fatigability or longer recovery time of the tongue.Maximal force, endurance, and recovery times of the tongue, electromyogram (EMG) absolute value, and EMG spectral analysis of the GGm obtained during submaximal contractions were compared in eight individuals without chronic snoring and eight OSAS patients.Endurance