Sleep Apnoea and Narcolepsy

Question 1

What is obstructive Sleep Apnoea Syndrome? Why does it usually occur?

Answer 1

Its when there is are recurrent episodes of obstruction in the upper respiratory tract whilst sleeping causing Apnoea. Usually between the pallitive soft tissue, end of tongue and posterior pharyngeal wall.

Usually occurs due to being overweight/narrowed parynx and relaxed surrounding muscles, related to snoring.

Causes unrefreshing sleep, daytime sleepiness (somnolence) and poor daytime concentration.

Question 2

Where is the level of the obstruction?

Answer 2

Usually between the soft palate, base of tongue and posterior pharyngeal wall.

Question 3

Do pharyngeal muscles relax when sleeping?

Answer 3

Yes

Question 4

What can cause closure of upper airway?

Answer 4

Pharyngeal muscle relaxation, narrow pharynx and obesity (decreasing the amount of free space). Negative pressure upon inhalation draws airway together, if already close, more likely to block.

Question 5

What is snoring?

Answer 5

The noise heard from vibrations of the base of tongue, on the soft palate/posterior wall of the pharynx

Question 6

Apnoea vs Hypopnoea?

Answer 6

Apnoea = cessation of breathing ( complete obstruction of airway) for 10s+
Hypopnoeas - Partial obstruction of airway - causes snoring for 10s+

Question 7

What is a microarousal and what are the consequences?

Answer 7

When the brain has to keep jumping from deep to light sleep to keep breathing. Not very restful at all!

Question 8

Why is OSAS Important?

Answer 8

Significantly affects Quality of Life
Can cause marital disharmony
Increased chance of Road Traffic Accident
Also associated with hypertension, increased risk of stroke and probably increased risk of heat disease

Question 9

What disease are OSA associated with?

Answer 9

Increased risk of hypertension, Increased risk of stroke and probably increased risk of heart disease

Question 10

Prevalence in the UK?

Answer 10

Probably
1% females, 2% males
Based on apnoea/hypopnea index of more than 5 (at least mild sleep apnoea)

Question 11

Diagnosis?

Answer 11

History and examination
Epworth Questionnaire
Sleep study tests (pulse ox./limited sleep studies/full polysomnography)

Question 12

What is the Epworth sleep questionnaire?

Answer 12

A comprehensive questionnaire asking patients to rate how likely they were to fall asleep/doze in various situations

Question 13

What score is considered abnormal for the Epworth questionnaire?

Answer 13

11+/24

Question 14

Pulse Ox overnight readings for OSA?

Answer 14

Normal readings are ox between 90-100% and HR relatively steady.

If has OSA then pulse ox will be dropping and rising between 70-90% repeatedly with the heart rate also fluctuating.

Question 15

What is central apnoea?

Answer 15

Caused by there not being the respiratory drive from the CNS to kick in and take a breath, no obstruction, just no stimulus. Much rarer than Obstructive Sleep Apnoea.

Question 16

What is Polysomnography?

Answer 16

The most sophisticated sleep study of them all!! 
Gives shed tonne of readings throughout the night including:
Oronasal airflow
Thoracoabdominal movement
Oximetry
Body position
EEG (E - Electricity, brainwaves)
EOG (O- Optomography, eye movements)
EMG (M-Movements, perhipheral)
ECG (C- Cardio)

Question 17

What is an EEG and what does it determine?

Answer 17

Brainwaves - determines if in deep/light sleep etc (stages of sleep) based on brain activity)

Question 18

EOG?

Answer 18

Eye moments (Optomography graph)

Question 19

EMG?

Answer 19

Perhipheral movements

Question 20

What is REM sleep?

Answer 20

Rapid Eye Movement sleep, usually dream sleep.

Sets in after approx 90 mins for most people but with narcolepsy sets in at start and ends of sleep.

Question 21

What is grading based on? What is Norma/mild/moderate

Answer 21

The no. Apnoeas/hypopneas per hour in the night (OR oxygen desaturation /hour/night if pulse ox was used)

Normal = under 5
Mild = 5-15
Moderate = 15-30
Severe = 30+

Question 22

Treatment??

Answer 22

Continuous Positive Airway Pressure management (CPAP) - mask
Mandibular repositioning splint (funky gum shield that pushes mandible forward)
Health factors that can be improved! eg weight loss, alcohol reduction before sleep, diagnose endocrine disorders eg hypothyroidism, acromegaly (pituitary gland produces too much growth hormone)

Question 23

Can patients with Sleep Apnoea drive?

Answer 23

Depends on how bad it is. May be doctors decision for driving to stop or at least be limited until symptoms are controlled. DVLA must be informed.

Question 24

Is Narcolepsy more or less common? Is it familiar?

Answer 24

Less common than sleep Apnoea (prevalence 0.05%). It can be familiar (run in families)

Question 25

Clinical features of Narcolepsy

Answer 25

Cataplexy (spontaneous collapse “falling asleep” but aware of surroundings - can be due to laughter or crying)
Excessive Daytime somnolence
Hypnagogic/hynopompic hallucinations (Hallucinations falling asleep/waking up - can be frightening, increase in REM at these times)
Sleep Paralysis

Question 26

Investigations?

Answer 26

Polysomnography
Wired up (brainwaves) and attempt to go to sleep at 4/5 points in the day - MSLT Multiple Sleep Latency Test, looking to fall asleep on average under 8 minutes
Test the Orexin in CSF. Often Low in Narcolepsy

Question 27

When does REM sleep occur? In narcolepsy?

Answer 27

At the beginning or at the End of sleep, sleep can begin with REM sleep)

Question 28

What is Orexin and how does it differe in narcolepsy?

Answer 28

Neuropeptide involved in controlling wakefullness. Low in Narcolepsy.

Question 29

What treatment of narcolepsy?

Answer 29

NOT cures, but help of symptoms.
Modafinil - stimulant
Dexamphetamine - Stimulant
Venlafaxine (for catcplexy) - serotonin reuptake inhibitor
Sodium Oxybate - second line treatment for sleepiness and cataplexy