Introduction
Obstructive sleep apnoea syndrome (OSAS) is a highly prevalent disorder of the upper airway occuring during the sleep cycle.1, 2, 3, 4 During sleep when the muscles relax, the soft tissue in the back of the throat collapse and upper airway is blocked. This results in hypopnoeas (partial reductions) and apnoeas (complete block) in breathing. During these episodes, there is typical oxyhemoglobin desaturation. Episodes are terminated by brief microarousals that result in sleep fragmentation and diminished amounts of slow wave and REM sleep.5 Patients usually present with loud habitual snoring, witnessed apnoea and excessive daytime sleepiness. Despite the high prevalence of OSAS in the general population, the condition is frequently unrecognized and undiagnosed as patients often regard their symptoms as normal variants and/or a manifestation of poor lifestyle. However, during sleep, patients have significant breathing problems, while awake most of them have no any detectable respiratory abnormality.6 Proper diagnosis at right time is very important for the disease to be cured. It includes signs, symptoms, questionnaire, imaging and polysomnography. The definitive diagnosis and grading of OSA require an overnight polysomnogram (PSG). Although imaging cannot diagnose OSA, it can strongly suggest the diagnosis.7 Various imaging modalities like Erect Lateral Cephalogram, Cone Beam CT Scan (CBCT), CT Scan and MRI can demonstrate significantly narrowed airway in patients with symptoms suggestive of OSAS.8
Prevalence
Prevalence of OSA increases between middle and older age group, however it can occur at any age. 4% of men and 2% of women shows OSA with resulting daytime sleepiness. Breathing symptoms of OSA with or without daytime sleepiness occurs in about 24 percent of men and 9% of women. Approximately 80-90% of adults with OSA remain undiagnosed. Prevalence of OSA in children is about 2% and is most common at preschool ages.9
Risk Groups9
People who are overweight (Body Mass Index 25-29.9) and obese (Body Mass Index ≥ 30).
Men and women with large neck circumference: ≥17 inches for men, ≥16 inches for women.
Middle-aged and older men, post-menopausal women.
People with head and neck abnormalities (the bony and soft tissue structure assessed with Cephalogram).
Adults and children with Down Syndrome.
Children with adenoids and large tonsils.
Retrognathia.
People having family history of OSA.
People with endocrine disorders (like Acromegaly and Hypothyroidism).
Smokers.
People suffering from nocturnal nasal congestion due to abnormal morphology, rhinitis or both.
Diagnosis of OSAS
Common OSAS signs10 include
Snoring.
Day time sleepiness or fatigue.
Restlessness during sleep.
Dry mouth or sore throat when wake up.
Difficulty in concentrating, forgetfulness or depression.
Headaches in the morning.
Night sweats.
Waking up suddenly and feeling like gasping or choking.
Trouble getting up in the mornings.
Waking up often in the middle of the night to pass urine.
Person may feel drowsiness, increasing the risk of accidents while driving or working.
High blood pressure.
Standardized questionnaires:
Questionnaires are increasingly being used in primary care both to screen high-risk patient groups for OSA and to identify those that would benefit from treatment if they have symptomatic OSA. Screening can be performed using the Berlin (BQ), STOP-Bang and OSA-50 questionnaires.11 The Epworth sleepiness scale (ESS)12 quantifies excessive daytime sleepiness.
Polysomnography
Obstructive Sleep Apnoea is diagnosed with a sleep study (polysomnography) which is carried out at an overnight sleep laboratory. This records eye and leg movements, brain waves, oxygen levels, airflow, and heart rhythm during sleep. The test is interpreted by a physician who specializes in sleep disorders. Also, Home Sleep Apnoea Testing (HSAT) can be done at home in place of the laboratory study. The number of apnoea and hypopnoea episodes that occur every hour i.e., Apnoea Hypopnoea Index (AHI) determines sleep apnoea severity:12
Imaging
Extensive research, using imaging performed during wakefulness and sleep, has confirmed a highly significant correlation between the dimensions and shape of the upper airway with the measure of airway collapsibility, as well as the AHI: the severity of OSA. The cheapest and most widely available research and assessment tool is the erect lateral cephalogram. There is a highly significant relationship between an inferiorly positioned hyoid bone and the severity of OSA.8
The key measurements of the upper airway during wakefulness8
Conclusion
As untreated sleep apnoea disorder progresses, it causes impaired performance at work. Patients with OSA can develop cognitive and neurobehavioral dysfunction, lack of concentration, memory impairment and mood changes like irritability and depression. This reflects their performance at work and quality of life may be affected. If remains untreated, OSA can lead to cardiovascular morbidity and mortality. Any individual with excessive daytime sleepiness or other symptoms of sleep apnoea can be diagnosed by signs, symptoms, questionnaires, imaging and polysomnography so that diagnosis may be made and treatment may be started at the earliest.
