Obstructive sleep apnea-hypopnea syndrome (OSAHS) is primarily caused by airway obstruction due to narrowing and blockage in the nasal and nasopharyngeal, oropharyngeal, soft palate, and tongue base areas. The mid-frequency anti-snoring device is a new technology based on sublingual nerve stimulation. Its principle is to improve the degree of oropharyngeal airway stenosis in OSAHS patients under mid-frequency wave stimulation. Nevertheless, there is a lack of clinical application and imaging evidence.

To investigate the clinical efficacy and mechanisms of a mid-frequency anti-snoring device in treating moderate OSAHS.

We selected 50 patients diagnosed with moderate OSAHS in our hospital between July 2022 and August 2023. They underwent a 4-wk treatment regimen involving the mid-frequency anti-snoring device during nighttime sleep. Following the treatment, we monitored and assessed the sleep apnea quality of life index and Epworth Sleepiness Scale scores. Additionally, we performed computed tomography scans of the oropharynx in the awake state, during snoring, and while using the mid-frequency anti-snoring device. Cross-sectional area measurements in different states were taken at the narrowest airway point in the soft palate posterior and retrolingual areas.

Compared to pretreatment measurements, patients exhibited a significant reduction in the apnea-hypopnea index, the percentage of time with oxygen saturation below 90%, snoring frequency, and the duration of the most prolonged apnea event. The lowest oxygen saturation showed a notable increase, and both sleep apnea quality of life index and Epworth Sleepiness Scale scores improved. Oropharyngeal computed tomography scans revealed that in OSAHS patients cross-sectional areas of the oropharyngeal airway in the soft palate posterior area and retrolingual area decreased during snoring compared to the awake state. Conversely, during mid-frequency anti-snoring device treatment, these areas increased compared to snoring.

The mid-frequency anti-snoring device demonstrates the potential to enhance various sleep parameters in patients with moderate OSAHS, thereby improving their quality of life and reducing daytime sleepiness. These therapeutic effects are attributed to the device’s ability to ameliorate the narrowing of the oropharynx in OSAHS patients.

Obstructive sleep apnea-hypopnea syndrome (OSAHS) is primarily caused by airway obstruction due to narrowing and blockage in the nasal and nasopharyngeal, oropharyngeal, soft palate, and tongue base areas. Its main clinical manifestations include snoring and associated breathing pauses during nighttime sleep. Most patients experience dry mouth upon waking in the morning, and some may also have symptoms such as headaches, daytime sleepiness, fatigue, lack of concentration, etc[1].

Transcutaneous electrical stimulation of the genioglossus muscle is a non-invasive treatment method for OSAHS [2]. Recently, a mid-frequency anti-snoring device has been developed that delivers specific pulse-modulated compound waves to provide intermittent electrical stimulation to the genioglossus muscle and its sublingual nerve branches. This leads to a responsive contraction of the genioglossus muscle, an increase in upper airway tension, a reduction in the severity of oropharyngeal upper airway collapse, and the maintenance of an open upper airway, ultimately terminating snoring. This device is beneficial for improving the quality of sleep in OSAHS patients.

This study focused on patients with moderate OSAHS and investigated whether the treatment with a mid-frequency anti-snoring device can improve various sleep parameters in OSAHS patients and enhance their quality of daily life. Additionally, it explores whether the airways in the oropharyngeal region expand under the stimulation of mid-frequency waves. Currently, there is a lack of imaging evidence in this regard. Therefore, this study conducted oropharyngeal computed tomography (CT) scans in OSAHS patients in awake, snoring, and mid-frequency anti-snoring device treatment states to measure the cross-sectional area at the narrowest points in the soft palate posterior and retrolingual areas. This approach aimed to provide imaging-based confirmation of the working mechanism of this technology in treating OSAHS.

With the advancement of medical diagnostic technology and increased awareness of personal health, the incidence of OSAHS in the population has increased. For example, a recent study found that out of 38000 Russian citizens (aged 30-70 years), 48.9% suffered from an AHI ≥ 5, 18.1% from an AHI ≥ 15, and 4.5% from an AHI ≥ 30[3]. OSAHS significantly impacts people’s safety, quality of life, social interactions, and relationships with family members. As such, it requires active intervention and treatment[4]. The pathological mechanism of OSAHS lies in the obstruction and collapse of the upper airway during sleep. The obstruction can occur in the nasopharynx, oropharynx, or hypopharynx, with over 80% of patients experiencing combined oropharyngeal obstruction[5]. Therefore, the core of OSAHS treatment is to relieve narrowing in the oropharyngeal region and keep the airway open.

Currently, OSAHS treatment includes general therapy, medication, devices, surgery, and rehabilitation[6]. Each treatment method has its advantages and limitations, and the treatment choice should be based on the patient’s specific condition. Hypoglossal nerve stimulation is one effective method for treating OSAHS, where a nerve stimulator is implanted under the patient’s skin in the neck and is connected to a sublingual nerve[7]. It stimulates the sublingual nerve to generate nerve signals synchronized with inhalation, helping the muscles tighten, pulling the tongue forward, expanding the pharynx, and relieving airway narrowing caused by the posterior displacement of the tongue root. However, this method is only effective in the short term, with limited long-term efficacy, and the equipment is expensive, restricting its clinical use[8].

In recent years, the mid-frequency anti-snoring device has been developed based on hypoglossal nerve stimulation, and it is a new technology used to treat OSAHS. It delivers specific frequency pulse-modulated composite waves and provides intermittent electrical stimulation to the genioglossus muscle and its sublingual nerve branches. This stimulates the genioglossus muscle to contract responsively, increases the tension of the upper airway, reduces airway collapse, and maintains airway patency, thus terminating snoring and apnea and improving sleep quality. While this method is theoretically feasible, it lacks clinical practice and research support. Therefore, this study aimed to explore this issue.

In the preliminary experiments of this study, it was found that mild OSAHS patients had low treatment willingness, poor compliance, and could not complete the entire study due to their mild symptoms. Therefore, they were not included in the study. Severe OSAHS patients, on the other hand, had more severe symptoms and showed unclear effects of the mid-frequency anti-snoring device. Clinically, they were mainly treated with non-invasive positive pressure ventilation. Therefore, they were not included either. Nevertheless, moderate OSAHS patients had a strong willingness to be treated, good compliance, and could complete the study. Therefore, they were chosen as the subjects of this study. The results of this study indicated that after 4 wk of treatment with the mid-frequency anti-snoring device, the AHI of moderate OSAHS patients decreased, the time of snoring during nighttime sleep decreased, the duration of the most prolonged apnea decreased, the duration of SPO₂ < 90% decreased, and the LSPO₂ increased, confirming a significant improvement in the patients’ nighttime sleep quality. The study results also indicated that the sleep apnea quality of life index scores of patients increased after treatment compared to before treatment, including social activity scores, emotional state scores, and symptom scores. The Epworth Sleepiness Scale scores decreased, confirming that this treatment improved the patient’s clinical symptoms and quality of life.

The study results also showed that after using the mid-frequency anti-snoring device, the number of AAI resp occurrences decreased, AAI non-resp decreased, and respiratory effort-related arousals decreased. OSAHS patients experience repeated awakenings during sleep, which hurts sleep quality. During the initial treatment phase, this study found that mid-frequency anti-snoring treatment increased patient awakenings, affecting sleep quality. The main reasons were that the initial stimulation intensity was too high, and patients had a low tolerance for stimulation. The study continuously adjusted stimulation intensity based on patients’ actual experiences. After a period, patients fully adapted, and the number of awakenings significantly decreased.

This study conducted oropharyngeal CT examinations on OSAHS patients in awake, snoring, and mid-frequency anti-snoring treatment states to confirm that the mid-frequency anti-snoring device worked by expanding the narrow oropharyngeal airway. The narrowest points of the airway in the soft palate posterior area and retrolingual area were chosen as measurement points, and the cross-sectional areas of the airways were measured. The results showed that in the awake state the cross-sectional area of the narrowest part of the soft palate posterior airway was 80.47 ± 18.56 mm² and the narrowest part of the retrolingual airway was 155.36 ± 13.29 mm². When patients snored during sleep, there was evidence of tongue root or uvula collapse, leading to oropharyngeal airway narrowing or obstruction. The cross-sectional area of the narrowest part of the soft palate posterior airway decreased to 22.05 ± 16.47 mm², and the cross-sectional area of the retrolingual airway decreased to 120.45 ± 12.23 mm² showing significant reductions. During mid-frequency anti-snoring treatment, the cross-sectional area of the narrowest part of the soft palate posterior airway was 71.61 ± 17.38 mm², and the cross-sectional area of the retrolingual airway was 150.61 ± 12.35 mm², showing significant improvement compared to the snoring state. The study results confirmed that during treatment with the anti-snoring device, the relaxation of the tongue root and uvula was alleviated, and the degree of oropharyngeal airway narrowing was significantly improved, providing strong evidence from an imaging perspective for the working mechanism of the mid-frequency anti-snoring device.

Several objective issues were encountered throughout this study, resulting in some limitations in the examination results. First, this study employed a natural sleep approach and did not use sedative-hypnotic drugs to induce sleep. The examination process was time-consuming and challenging. In addition, patients were influenced by unfamiliar environments, such as the low temperature and high noise in the CT examination room, making it difficult for OSAHS patients to fall asleep naturally. Consequently, CT examinations were prone to interruptions and were not reflective of the patient’s actual home sleep state, potentially affecting the accuracy of the examination results. Second, the number of cases included in this study was relatively small, which may lead to statistical bias. Third, differences in patient height, weight, and disease severity, as well as differences in upper airway anatomy, could impact CT examination results. Fourth, during treatment with the anti-snoring device, high pulse stimulation intensity could cause patient awakenings, affecting the accuracy of CT examinations. Resolving the above issues requires further increasing the number of patients, expanding the sample size, improving the environment in the CT examination room, optimizing the CT examination process, and using sedative-hypnotic drugs to induce sleep if necessary.

In conclusion, this study confirmed that the mid-frequency anti-snoring device can expand the oropharyngeal airway in patients with moderate OSAHS, thereby improving their clinical symptoms and sleep quality. Our study provided a new method for the clinical treatment of OSAHS.