Tiredness and fatigue are common reasons for presenting to GPs. Obstructive sleep apnoea (OSA) is one of the more important causes of daytime somnolence because of the potentially serious systemic effects it has on multiple organ systems, as well as its effect on quality of life. The ENT surgeon has a role to play in the surgical management of both children and adults with this syndrome — for primary surgical treatment of an obstructive lesion or to improve nasal airflow for CPAP. In the Australian adult population, the prevalence of moderate to severe OSA is estimated to be 4.7%, with a higher prevalence in men than women. This figure underestimates the true burden of the disease, with many more people having symptoms of undiagnosed OSA. In children, the prevalence is estimated to be around 2%.
The pathophysiological process that causes OSA is upper airway collapse while sleeping. The mechanism is a combination of an easily collapsible upper airway with the relaxation of pharyngeal dilator muscles that normally occurs during sleep. Anatomical factors that can contribute to upper airway collapse include obesity, soft tissue hypertrophy (including tonsillar, adenoid and lingual tissue), macroglossia and micrognathia (relatively short mandible). These factors will all increase the extraluminal tissue pressure surrounding the airway Anatomical factors are not always the cause of OSA, however, and patients without obvious risk factors may have a problem with reflex pathways from the central nervous system to the pharyngeal dilator muscles.
Anatomically, the three major areas of obstruction are the nose, oropharynx and hypopharynx. Nasal obstruction may be caused by nasal septum deviation, turbinate hypertrophy and/or adenoid hypertrophy and can lead to open-mouth breathing during sleep. Mouth breathing, in turn, increases upper airway collapsibility, destabilises the oral tongue and may decrease the effect of the dilator muscles. In children, adenotonsillar hypertrophy is the major cause of OSA. However, other structural factors such as craniofacial abnormalities can also play a role in upper airway collapse.
Daytime hypersomnolence and loud snoring are the most common presenting complaints of adults with OSA. Other symptoms and signs include morning headache, restless sleep, or waking unrefreshed despite a good duration of sleep. The Epworth Sleepiness Scale is a commonly used tool to assess daytime sleepiness, with a score greater than 10 raising suspicion of OSA. General physical examination includes BMI calculation, blood pressure and assessment of body habitus. The nose should be assessed for external deformity and septal deviation.