Sleep Disorders

Question 1

What is Narcolepsy?

List the Tetrad of Narcolepsy.

Answer 1

= autoimmune disease characterized by excessive daytime sleepiness, mild to extreme limb cataplexy, sleep paralysis and hypnagogic hallucinations.

Tetrad of Narcolepsy
• Excessive daytime sleepiness
• Mild to extreme cataplexy (limb weakness in emotional episodes)
• Sleep paralysis
• Hypnagogic hallucinations (vivid dream recollection prior to wakening)

Question 2

What is the pathophysiology of Narcolepsy?

Answer 2

• Autoimmune condition –> Loss of orexinergic neurons in lateral hypothalamus ≈ reduced activation of arousal nuclei + reduced inhibition of VLPO ≈ sleeping more

Question 3

Outline the investigations you may wish to carry out in a patient with suspected Narcolepsy.

Answer 3

• Epworth sleepiness questionnaire
• Polysomnography (EEG, EMG, record movements, record breathing, vital signs and ECG): snoring, frequent awakenings, reduced sleep efficiency, periods of REM in first 15 minutes sleep, multiple arousals
• Multiple sleep latency test (MSLT): < 8 minutes plus > 2 sleep-onset REM periods (SOREMs)
• Actigraphy and sleep diary (non-invasive test measuring activity via actimetry sensor): No evidence of short sleep duration; no circadian disorder explaining symptoms

• CSF Hypocretin-1 (Orexin) level: Low or undetectable in 90%

Question 4

Outline the treatment for a patient with diagnosed Narcolepsy.

Answer 4

• Sleep hygiene + lifestyle changes: reduce caffeine/shiftwork/15-30 min naps/clean area

• CNS Stimulant:
- 1º: Modafanil 200mg PO OD in morning (max 400mg/day)/
- 2º: Dexamfetamine 5-10mg PO (max 60mg/day)/
- 2º Methylphenidate 10-60mg/day PO OD in 2-3 divided doses
- 3º: Sodium oxybate (GHB)
• SSRs and TCAs: Suppress REM sleep
• Avoid triggers: Venlafaxine (anti-depressant ≈ reduce cataplexy)

Question 5

What is Sleep Apnoea?

Answer 5

= episodes of complete or partial upper airway obstruction during sleep

Question 6

What are the risk factors for sleep apnoea?

Answer 6

• Male
• Post-menopausal women
• FHx OSA
• Increasing age
• Obesity
• Maxillomandibular anomalies
• Macroglossia

Question 7

Outline the pathophysiology of Sleep Apnoea.

Answer 7

• Upper pharyngeal dilator muscle activity decreases with sleep onset + both tonic and phasic dilator reduced in REM sleep + narrow pharyngeal cross-sectional area ≈ obstructed pharynx ≈ hypoxemia + hypercapnia ≈ feedback ≈ sympathetic activation ≈ cardiac dysrhythmias + vasoconstriction

Question 8

List the signs and symptoms of Sleep Apnoea.

Answer 8

• Excessive daytime sleepiness
• Episodes of apnoea
• Episodic gasping
• Restless sleep
• Insomnia
• Chronic snoring

Question 9

Outline the investigations you may wish to conduct in a patient with suspected Sleep Apnoea.

Answer 9

• PSG: Apnoea-Hypopnoea Index (AHI) > 15 episode/hour
• Portable multichannel sleep tests: Respiratory Event Index (REI) > 15 episodes/hour
• Awake fibreoptic endoscopy: Nasal polyps or tumours

Question 10

Outline the management for a patient with sleep apnoea.

Answer 10

• CPAP
• Upper airway surgery
• Weight loss
• Modafinil/Armodafinil

Question 11

What is insomnia?

Answer 11

sleep disorder by which you have trouble falling asleep ± staying asleep.

Question 12

List the risk factors for insomnia.

Answer 12

• Female sex
• Advancing age
• Chronic physical illness
• Chronic psychological illness
• Use of alcohol/drugs/stimulants

Question 13

Outline the signs and symptoms of insomnia.

Answer 13

• Partner sleep complaints
• Delayed sleep onset
• Multiple/long awakenings
• Accidents
• Impairments of functioning
• Decreased sleep time

Question 14

Outline the investigations for a patient with insomnia.

Answer 14

• Epworth Sleepiness Scale: ≥ 9
• PSG: Variable finds
• Actigraphy: Abnormal circadian rhythm, patterns or sleep disturbances

Question 15

Outline the management for someone with insomnia.

Answer 15

• CBT-I
• Sleep hygiene + relaxation techniques
• Hypnotic: Zolpidem 5-10mg PO OD
• Antidepressant