Narcolepsy Flashcards
What is the epidemiology of narcolepsy?
Rare – 25,000 in the UK
M/F equally affected
Onset often during adolescence but can go undiagnosed until between 20-40yrs
What is the aetiology and pathophysiolgoy of narcolepsy?
Lots of cases hypothesised to be due to deficiency in hypocretin (orexin) = Neruopeptide used in sleep regulation, arousal and appetite
Thought to be due to an autoimmune response to proteins called trib 2 that are present in areas of the hypothalamus that also produce hypocretin – destruction leads to deficiency
What are some triggers for narcolepsy?
Inherited genetic fault
Hormonal changes
i) Puberty
ii) Menopause
Major psychological stress
Sudden change in sleep patterns
Infection
i) Strep
ii) Flu vaccine Pandemrix (small risk)
What is secondary narcolepsy?
Developing due to:
i) Head injury
ii) Brain tumour
iii) MS
iv) Encephalitis
How does narcolepsy present?
May develop slowly (yrs) or acutely (wks)
Excessive daytime sleepiness – can impact on functioning (concentration, coordination etc)
Sleep attacks – falling asleep suddenly and without warning; can be short (s) ‘microsleeps’ or long (mins); may occur several times during day
Cataplexy
Sleep paralysis – temporary inability to move/speak when waking up/falling asleep; seconds-minutes; anxiety inducing - may see figures (hypnopompic hallucinations)
Memory problems, headaches, restless sleep, insomnia, depression
What is cataplexy?
Sudden temporary muscle weakness or loss of muscular control – jaw dropping, head slumping, legs collapsing uncontrollably, slurred speech, double vision
Usually triggered by emotion ie excitement/laughter/surprise
Seconds-minutes; daily/yearly
People may become withdrawn to avoid triggering
Is rare without narcolepsy
How is narcolepsy investigated clinically?
Sleep/symptom diary
Epworth sleepiness questionnaire:
Used to assess how likely you are to fall asleep whilst doing certain activities ie reading, watching TV, travelling as a passenger in a car
<10 = comparable to general population, 11< increased daytime sleepiness – specialist referral
Hx:
Talk me through your symptoms
What is your sleep routine like? Hrs? Caffeine intake?
Mood? Impact on daily functioning?
Recent head injury?
Bowel habit? Temperature?
Medication history – some can cause drowsiness
Physical examination + Obs: Thyroid Anaemia Cranial nerves/neuro Body temp/BP/HR/Sats etc
Bloods:
FBC
TFT
What does specialist sleep analysis involve?
Referral to specialist sleep clinic:
Polysomnography -
Overnight stays for: EEG; ECG; EMG; EOG; Video/movment of chest/abdomen; Airflow though nose/mouth + pulse oximetry
Multiple sleep latency test:
How long to fall asleep during the day – asked to take several naps
If you fall asleep and into REM quickly – likely narcolepsy
Genetic markers:
HLA DQB *0602 - +ve supports but doesn’t confirm Dx (30% of people without narcolepsy also have marker)
Hypocretin levels:
LP to measure levels in CSF
How do you self manage narcolepsy?
No cure but symptoms remediable
Good sleeping habits: Frequent, brief naps evenly though day Sticking to a bedtime routine Relaxing before going to bed Bedroom a comfortable temperature, quiet and free from distractions Avoid caffeine, alcohol and smoking Not exercising 2hrs before bed Not eating large heavy meals before bed Avoid drowsiness inducing medicines during the day
Co-support: Talk to others with narcolepsy
What drugs can be given for narcolepsy?
Stimulants:
i) Modafinil, dexamphetamine or methylphenidate
ii) SEs: Headaches; GI disturbance – N, pain, weight loss; Nervousness; Insomnia; Irritability; HTN, arrhythmia – regular monitoring during treatment
Antidepressants:
i) Unknown efficacy but can be helpful with cataplexy, hallucinations and sleep paralysis
ii) Fluoxetine; venlafaxine; clomipramine
iii) Thought to reduce REM
What is the law on driving and narcolepsy?
May affect ability to drive:
i) Stop driving immediately and inform DVLA
ii) DVLA will review you (regularly) and if medically well controlled will be able to drive
