Table 2. Summary of the reviewed articles.

Reference	Study Design	Year of Publication	Sample Size (n)	Finding
Patrick J. Strollo et al. [11]	Randomised control Trial	2014	126	Following unilateral stimulation of the genioglossal muscle or hypoglossal nerve in sync with ventilation, there were significant and clinically significant reductions in the severity of obstructive sleep apnoea and self-reported sleepiness as well as improvements in quality-of-life measures in patients with obstructive sleep apnoea who had difficulty accepting or adhering to continuous positive airway pressure (CPAP) therapy at one-year follow-up.
Ursula G. Schulz et al. [12]	Randomised controlled Trial	2013	183	There is no relationship between obstructive sleep apnoea (OSA) and leukoaraiosis or 'age-related white matter changes.
Shu Y et al. [13]	Randomised controlled Trial	2018	603	During inspiration, the patency of the upper airway is compromised or collapses. Such collapse is the the comprehensive outcome of several multifactorial interactions involving functional and anatomical components. The combination of pharyngoplasty and tonsillectomy offers considerable potential for treating children with obstructive sleep apnea.
Bradley A. Edwards et al. [14]	Randomised controlled Trial	2016	14	OSA is a complex illness that isn't just brought on by a dysfunctional upper-airway structure and several additional nonanatomic characteristics, such as (1) the inability of the pharyngeal muscles to keep the airway open or make it rigid, (2) a ventilatory control system that is too sensitive (i.e., high loop gain), and (3) Low respiratory arousal threshold is another factor in the development of OSA.
Bradley A. Edwards et al. [15]	Randomised controlled Trial	2016	20	The combination of mandibular advancement and electrical genioglossus stimulation is effective in managing OSA. In individuals whose anatomy is not seriously impaired, reducing loop gain and raising the arousal threshold together is an efficient treatment for OSA.
Kazuomi Kario et al. [16]	Randomised controlled Trial	2016	535	OSA patients who received renal denervation had significantly lower office systolic blood pressure at 6 months than sham control patients. Renal denervation significantly decreased overnight systolic blood pressure in non-dippers (persons with a fall of less than 10% in nocturnal arterial blood pressure), which further demonstrated that renal denervation had an impact on these patients' sympathetic drive.
Ying-Chun Cao et al. [18]	Randomised controlled Trial	2018	72	The use of low-temperature plasma to remove tonsils from individuals with oropharyngeal blockage and obstructive sleep apnoea has been proven to be both safe and effective.
Finn Geoghegan et al. [21]	Randomised Controlled Trial	2015	45	Significant cephalometric alterations caused by mandibular advancement devices (MAD) around the hyoid bone's position and the soft palate's length suggests that MADs may affect the position of the local muscles and enhance patency of upper airway.
Blanca Ferrandez et al. [22]	Randomised controlled Trial	2014	191	Retinal sensitivity was significantly reduced in OSA patients compared with healthy subjects. Retinal ganglion cells provide a peripheral window into the central nervous system neurons, which may be damaged as a result of OSA.
Ali Talib et al. [23]	Randomised controlled Trial	2020	43	The majority of severely obese teenagers have Left Ventricular Hypertrophy, and unfavourable geometrical changes, particularly increased Interventricular septal thickness, are independently linked to several frequently occurring nonhemodynamic risk factors, such as OSA, dyslipidaemia, and insulin resistance.
Jouett NPet al. [24]	Randomised controlled Trial	2016	9	Intermittent hypoxia training (IHT) causes large increases in muscle sympathetic nerve activity and arterial pressure that lasts even when people breathe normally in the room air. This offers a potentially significant mechanistic explanation for the ongoing daytime muscle sympathetic nerve activity elevations are seen in OSA patients.
Schmickl CN et al. [25]	Randomised controlled Trial	2020	20	In patients with OSA, the pharyngeal muscles' central activity decreases significantly and quickly during the wake-sleep transition, which may be a factor in the the emergence of apnoeas and hypopnoeas. A decline in noradrenaline levels may also be important.
Jacq O et al. [28]	Randomised controlled Trial	2017	10	The muscles that dilate the upper airways, especially genioglossus, which are mostly innervated by the hypoglossal nerve, is necessary to maintain their patency throughout the breathing cycle. Osteopathic treatment of the sphenopalatine ganglion may help those with obstructive sleep apnea syndrome maintain pharyngeal stability.
Goh KJ et al. [32]	randomized crossover trial	2018	85	The relationship between craniofacial morphology and OSA is becoming more widely recognized, and it is more prominent in Asian populations than in Caucasian populations. Adherence to nasal masks, as opposed to oronasal masks and nasal pillows were highest for obstructive sleep apnoea (OSA) patients receiving continuous positive airway pressure (CPAP) therapy. When starting CPAP, nasal masks should be the first interface used.
Carter SG et al. [35]	Randomised controlled Trial	2016	12	OSA, as assessed by the apnoea-hypopnea index (AHI), is related to the genioglossus movement patterns while silent breathing awake. In contrast to airway dilatation during sleep is hypothesised that increased 23 genioglossus neural drive combined with counterproductive genioglossus motion during waking will induce velopharyngeal closure.
Doff MH et al. [36]	Randomised controlled Trial	2013	103	Oral appliances that cause mandibular protrusion aid patients with OSA but they are viewed as a lifelong treatment option.
Blake KV et al. [37]	Randomised controlled Trial	2019	75	Adenoids and tonsils play a pivotal role in causing OSA in children and adenotonsillectomy is the most common (90%) operation performed in children 0 to 6 years old for airway obstruction or sleep disruption.
Kasai T et al. [38]	Randomised controlled Trial	2014	24	The Upper Airway lumen can become constricted and have an impact on the AHI when fluid from the legs are displaced into the soft the tissue of the pharynx while you sleep. Therefore, in OSA patients, fluid redistribution from the lower to the upper body while reclining may aid in upper airway narrowing and increasing the chance of it collapsing as you sleep. On the other hand, there seem to be mechanisms that cause UA dilation in response to the the rostral fluid shift in people without sleep apnoea, which could prevent the onset of OSA.
Yadollahi A et al. [39]	Randomised controlled Trial	2014	17	In comparison to younger men, older men are more vulnerable to the negative impacts of loading intravenous fluid on the severity of obstructive sleep apnoea. The collapsibility of the upper airways in response to loading intravenous fluid or age-related changes in the quantity of the fluid that builds up in the neck could be to blame for this. Additionally, the Upper Airway dilator reflexes may weaken with age, and older people (those over 40) have much weaker ventilatory and genioglossus muscle responses to hypoxia than younger people.
Glos M et al. [40]	Randomised controlled trial	2016	40	The potential benefits of OSA will vary trial depending on aspects including younger age, lower weight, female gender, and certain craniofacial characteristics.