3. Blackout Flashcards
What’s the difference between syncope and LoC?
Syncope - due to hypo-perfusion of the brain
LoC can be syncopal or non-syncopal
What are the mechanisms of syncope?
Reflex - play dead, HR and BP drops
Cardiac - drop in CO
Orthostatic/ postural
Cerebrovascular - obstructions to blood flow between heart and brain - uncommon
What are the causes of LoC?
Syncopal:
- Reflex - Vasovagal syncope, carotid sinus hypersensitivity, situational syncope
- Cardiac - Arrhythmias, Aortic stenosis, HOCM
- Orthostatic - Drugs (anti-hypertensives, anti-sympathetics), dehydration, autonomic instability, baroreceptor dysfunction
- Cerebrovascular - Vertebrobasilar insufficiency, subclavian steal, aortic dissection
Non-syncopal:
- Intoxication - alcohol, sedatives
- Head trauma
- Metabolic - hypoglycaemia
- Psychogenic (non-epileptic) seizure
- Epileptic seizure
- Narcolepsy
What is commonest cause of LoC in patient aged 25?
Young:
Vasovagal syncope
- with warning, presyncopal sensation
What is commonest cause of LoC in patient aged 55?
Middle-aged:
Vasovagal syncope or cardiac arrhythmias
(CA usually secondary to IHD)
- no warning
What is commonest cause of LoC in patient aged 85?
Elderly:
Orthostatic hypotension caused by medications
e.g. diuretics, ACEi - reduce blood vol and vasodilation
b-blockers - prevent increase in HR on standing
a-blockers - prevent vasoconstriction of major capacitance veins
CCB - prevent vasoconstriction and -ve inotropic/chronotropic
Which questions should you ask about what happened BEFORE the LoC episode?
Before LoC:
- any warning?
no warning = cardiac or cerebrovascular
aura = epileptic seizure
vasovagal = dizziness - any precipitating factors?
postural = orthostatic
head turning = carotid sinus hypersensitivity
sitting/lying down = cardiac arrhythmia
exercising = primary cardiac pathology e.g. aortic stenosis, cardiomyopathy (HOCM), cardiac channelopathy (long QT syndrome)
Vigorous arm activity = subclavian steal - recent head trauma?
elderly and alcoholics - trauma days/weeks earlier + subsequent seizures
Which questions should you ask about what happened DURING the LoC episode?
During LoC:
- how long did LoC last - seconds or mins
seconds = vasovagal or arrythmia - bite tongue, move limbs or incontinent (urine/faeces)?
bite tongue = epileptic seizure
twitching and incontinence can be other e.g. vasovagal
Which questions should you ask about what happened AFTER the LoC episode?
After LoC:
-did they recover spontaneously? if not how long to recover? confused after recovery?
spontaneous = not metabolic/neurological except epilepsy
slow recovery with confusion = epileptic seizure
Describe the features of LoC due to epilepsy
Before:
- sterotyped aura - partial seizure
- no warning - general seizure
During:
- lasts mins
- stereotypes episodes (same every time)
- tongue biting
- twitching and incontinence may occur
After:
- slow recovery
- confused for 5-30 mins
Describe the features of LoC due to vasovagal causes (i.e. faint)
Before:
- vagal symptoms - sweating, pallor, nausea
- may have precipitant e.g. fear
During:
- lasts seconds
- may have twitching or incontinence
After:
- rapid recovery on sitting/lying
Describe the features of LoC due to arrhythmia
Before:
- no warning
- may have palpitations
During:
- lasts seconds
- may have twitching or incontinence
After:
- rapid, spontaneous recovery
What would you ask about PMH?
has it happened before?
- ask same Q about prev episodes and if increasing freq
diabetes
- predisposes to vasc disease, hypoglycaemia, polyuria, dehydration, autonomic dyfunction - can cause orthostatic hypotension
cardiac illness
- palpitations and chest pain, HD = cardiac syncope, ?arrythmias after infarction, ?LV outflow obstruction after aortic stenosis or HOCM?
peripheral vasc disease
- associated with coronary artery disease and cerebrovasc events (TIA/stroke)
epilepsy
- same as typical seizure?
anaemia
= hypoxia - pt history of myelodysplastic syndrome, melenea or freq blood transfusions
psychiatric illness
- panic attacks associated with hyperventilation and LoC
- non- epileptic seizures
What questions would you ask about drug history?
Insulin, oral hypoglycaemics (not metformin - increases sensitivity to insulin)
Anti-hypertensives - diuretics, ACEi, b-blockers, CCBs
Vasodilators - GTN
Anti-arrhythmics - can paradoxically predispose to arrhythmias
Antidepressants - TCAs - hypotension is SE
Warfarin and and anti-coagulants - subdural haemorrhages
What questions would you ask about social history?
Alcohol
Stimulant recreactional drugs - cocaine, amphetamines = tachyarryhtmias and drop in CO
