QuestionSBA
QuestionChoice
Acting out dreams can indicate a REM disorder. This can be an early feature of Parkinson's disease, where a DaTscan can illustrate loss of dopaminergic neurones in the basal ganglia. However, given the patient demographics and the absence of any parkinsonian features, the more likely underlying cause of the REM sleep disorder is OSA. The first-line investigation would be polysomnography.
52943
b
DaTscan
QuestionChoice
Waking in the middle of the night can occur in the context of heart failure, where the patient reports waking up breathless and coughing pink, frothy sputum (paroxysmal nocturnal dyspnoea (PND)). In this case, there are no reported heart failure symptoms, such as shortness of breath, PND, orthopnoea or ankle swelling. The clinical presentation is more in keeping with OSA.
52946
e
Brain natriuretic peptide
QuestionChoice
The history of snoring and daytime somnolence in a patient who is obese points towards a diagnosis of obstructive sleep apnoea (OSA). Acting out dreams can be a rapid eye movement (REM) disorder, which can also be seen in a small number of these patients. The first-line investigation for OSA would be polysomnography.
52942
a
Polysomnography
QuestionChoice
Enlarged tonsils, adenoids or a narrowed airway can be risk factors for OSA. A laryngoscopy could be used to evaluate any structural abnormalities narrowing the airway. However, this is not first line and is generally reserved for patients undergoing potential surgical treatment, where standard medical therapy such as continuous positive airway pressure has failed or not been tolerated.
52945
d
Laryngoscopy
QuestionChoice
A sleep diary is unlikely to yield much additional information since the patient and his wife have already given detailed accounts of his sleep patterns. Their accounts point towards a diagnosis of OSA; therefore, he should be referred for polysomnography.
52944
c
Sleep diary
Concept
Chapter
# Summary

Obstructive sleep apnoea (OSA) is caused by intermittent obstruction of the upper airways during sleep when there is loss of oropharyngeal muscle tone. Patients predisposed to this include those with obesity, large neck circumferences, anatomically smaller airways and decreased muscle tone due to alcohol or drugs (amongst other risk factors). The intermittent airway obstruction and resulting hypoxaemia leads to frequent awakening from sleep and so symptoms include excessive daytime sleepiness, morning headaches and poor concentration. The diagnostic investigation is polysomnography (a sleep study) to determine how many apnoeic or hypopnoeic episodes a patient is experiencing. Treatment includes modifying risk factors such as excess body weight and sleeping position, and continuous positive airway pressure (CPAP) devices to prevent airway obstruction overnight. 

# Definition

Obstructive sleep apnoea (OSA) is a condition where the upper airway becomes completely or partially obstructed during sleep, causing apnoeas (where breathing temporarily stops) or hypopnoeic episodes (decreased airflow during breathing). These episodes cause oxygen desaturations which cause brief arousals from sleep which can be hundreds of times per night. This leads to poor sleep quality which causes symptoms of daytime drowsiness, morning headaches and impaired concentration.

# Epidemiology

OSA is common, affecting an estimated 1.5 million adults in the UK, however around 85% of these are undiagnosed. Around half of people affected are overweight or obese, with 40% of obese people and 77% of morbidly obese people having OSA.

OSA is strongly linked with cardiovascular disease and the metabolic syndrome, and is a significant risk factor for coronary artery disease, type 2 diabetes and stroke.

Daytime sleepiness is an important consideration, especially in patients who drive or whose jobs require vigilance. Patients who drive for work and so are on the road for long periods of time and may be driving large vehicles are of particular concern due to the increased risk of injury to themselves and other road users.

# Aetiology

During sleep there is a normal loss of muscle tone in the oropharynx. In most people, there is still sufficient airway patency during sleep so that it does not become obstructed. Patients with OSA, however, require the muscle tone when awake to counteract additional pressures on their airway and so are unable to maintain patency when asleep.

Risk factors for OSA include:

- Obesity
- Male sex
- Older age
- Decreased muscle tone - e.g. alcohol excess, sedative medications, muscular dystrophy or other neuromuscular disorders
- Anatomical defects - e.g. retrognathia, macroglossia
- Large neck circumference
- Adenotonsillar hypertrophy (particularly in children)
- Sleeping supine
- Down’s syndrome

# Signs and symptoms

- Unrefreshing sleep, or frequent waking at night
- Daytime sleepiness
- Others may witness snoring, apnoeas, gasping or choking during sleep
- Difficulty concentrating
- Morning headaches
- Behavioural problems and hyperactivity in children

On examination, patients may be drowsy and may have some of the risk factors above such as:

- Obesity (check BMI)
- Large neck circumference (can measure or ask collar size) 
- Jaw abnormalities (retrognathia or micrognathia)
- Mouth breathing or nasal speech (due to nasopharyngeal obstruction, e.g. due to adenotonsillar enlargement)

Also look for signs and symptoms of complications of OSA such as hypertension or arrhythmias. 

# Differential Diagnosis

- **Insomnia** - defined as difficulty falling asleep, staying asleep or poor sleep quality that leads to daytime impairment, commonly associated with other mental and physical health conditions
- **Sleep disturbance** - for example due to shift work
- **Restless legs syndrome** - patients get irresistible urges to move their legs accompanied by unpleasant sensations, often at night disturbing sleep
- **Narcolepsy** - excessive daytime sleepiness, sudden attacks of sleep, excessive dreaming are common, may be associated with cataplexy (sudden loss of muscle tone, often triggered by strong emotions)
- **Hypothyroidism** - also a risk factor for OSA, causes fatigue, poor concentration, weight gain and depression among other symptoms
- **Depression** - associated with OSA, overlapping symptoms include low energy levels, poor concentration and low mood
- **Medications** - SSRIs, antiepileptic medications and benzodiazepines can cause symptoms of daytime sleepiness and disturbed sleep
- **Gastro-oesophageal reflux disease** - mimics nocturnal symptoms of choking and gasping, can disturb sleep

# Investigations

Initial screening for OSA symptoms and severity should be done using a questionnaire - the two recommended are STOP-Bang and the Epworth sleepiness scale.

**STOP-Bang** asks about snoring, sleepiness, apnoeas, hypertension, obesity, neck circumference, age and sex and gives a low, medium or high risk of OSA.

The **Epworth sleepiness scale** focuses on daytime sleepiness and asks how likely the patient would be to fall asleep in a variety of situations (e.g. when watching TV). This gives a result of either normal daytime sleepiness or mild, moderate or severe excessive daytime sleepiness.

The definitive investigation is **polysomnography** (also called a sleep study) which would usually be arranged by a specialist clinic.

Patients should be referred for this urgently (to be seen within 4 weeks) if:

- Excessive sleepiness is impacting on their safety to work (e.g. professional driver)
- They have a related comorbid condition such as treatment resistant hypertension or COPD
- They have upcoming major surgery 
- They are pregnant

Patients who do not fall into the above categories but have moderate or severe OSA or mild OSA which is impacting quality of life should be referred routinely to a sleep clinic for consideration of polysomnography.

Usually polysomnography is done as an outpatient and patients can do the study at home overnight. In some situations an overnight admission may be required.

The study looks at how many episodes of apnoeas or hypopnoeas lasting 10 seconds or more patients have per hour of sleep (referred to as the apnoea-hypopnoea index or AHI). Five or more is diagnostic of OSA and severity is classified as below:

- Mild OSA: AHI 5-14 per hour
- Moderate OSA: AHI 15-30 per hour
- Severe OSA: AHI over 30 per hour

The number of episodes of oxygen desaturation per hour is also measured, with more episodes of desaturation predictive of poorer cardiovascular outcomes.

# Management

**Conservative management includes:**

- Patient education, especially concerning driving (see section on driving advice)
- Advise to sleep on their side rather than supine where possible (aids such as repositioning pillows may be of help)
- Weight loss advice and support (including diet, exercise, medications and surgery)
- Reduction in alcohol intake
- Smoking cessation

**Medical management includes:**

- Continuous Positive Airway Pressure (CPAP) therapy - this is first line in symptomatic OSA and is a long-term treatment. 
- A mask over the nose or face is used to deliver additional airway pressure that splints open the airways and prevents the collapse seen in OSA. 
- Education and support are key as tolerance can be a problem and masks need to fit well to be effective.
- If patients do not tolerate or respond to CPAP, an intra-oral mandibular advancement device is another option. 
- These devices pull the mandible forward, opening the airway and preventing obstruction. 
- Management of comorbidities including hypertension, diabetes and depression is also important.

**Surgical management includes:**

- In cases where there is oropharyngeal obstruction e.g. due to adenotonsillar enlargement, surgery may be considered to relieve this for example a tonsillectomy.

# Driving advice

All patients with daytime sleepiness due to OSA should be advised as follows:

- If OSA is suspected or mild, advise patients not to drive until symptoms are controlled. If this is not achieved within 3 months, they should inform the DVLA.
- If OSA is moderate or severe, patients should inform the DVLA immediately and not drive; this will be reviewed by the DVLA and they may be allowed to drive once symptoms are controlled.

This is the same for group 1 drivers (cars and motorbikes) and group 2 (lorries, buses and coaches), however group 2 drivers returning to driving after symptom control is achieved require annual reviews of this (rather than 3 yearly for group 1 drivers).

# Complications

Complications related to daytime sleepiness include:

- Road traffic collisions - patients with OSA have a 2.5x increased risk compared to those without the condition
- Accidents at home or at work
- Deterioration in mental health, including irritability and depression

Cardiovascular and metabolic complications include:

- Stroke
- Coronary artery disease
- Hypertension that may be treatment resistant
- Congestive heart failure
- Type 2 diabetes

# NICE Guidelines

[NICE CKS - Obstructive sleep apnoea syndrome](https://cks.nice.org.uk/topics/obstructive-sleep-apnoea-syndrome/)

# References

[Patient UK - Obstructive sleep apnoea](https://patient.info/doctor/obstructive-sleep-apnoea-syndrome-pro) 

[British Lung Foundation - OSA Toolkit](https://www.asthmaandlung.org.uk/sites/default/files/OSA_Toolkit_2015_BLF_0.pdf) 

[DVLA - Tiredness can kill: advice for drivers](https://www.gov.uk/government/publications/tiredness-can-kill-advice-for-drivers)
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Polysomnography is the gold standard investigation for diagnosing obstructive sleep apnoea, it simultaneously records brain activity, eye movement, muscle activity, heart rate, respiratory effort, airflow, and oxygen saturation during sleep to identify apneic episodes and assess their severity.
A 42-year-old man attends his GP after a 6-month history of difficulty sleeping. He reports waking up multiple times a night gasping for breath and then napping more regularly in the day. His wife has also noticed that he tends to act out his dreams while asleep and snores heavily. On examination, his body mass index is 35 and otherwise unremarkable.

What is the best next investigation for his poor sleep?
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