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Oxford Clinical Cases > Blackout > Flashcards

Blackout Flashcards

1
Q

Define syncope.

A

A form of loss of consciousness in which hypoperfusion of the brain is the cause

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2
Q

List the four main mechanisms of syncope.

A

Reflex – caused by a primitive reflex that leads mammals to play dead. It causes a temporary drop in blood pressure.
Cardiac
Orthostatic
Cerebrovascular – non-cardiac structural causes of reduced cerebral perfusion (RARE)

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3
Q

How can the cardiac causes of syncope be further divided?

A

Arrhythmia
Outflow obstruction (e.g. aortic stenosis, HOCM)
Postural hypotension

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4
Q

What can cause orthostatic hypotension?

A

Blunting of the normal autonomic response to standing up (vasoconstriction + rise in heart rate)
It is most commonly due to drugs or autonomic neuropathy

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5
Q

What are some of the causes of syncope (that fall under the four mechanisms)?

A 
Reflex
Vasovagal syncope
Other: carotid sinus hypersensitivity
Cardiac
Arrhythmias
Outflow obstruction
Orthostatic
Drugs 
Dehydration
Autonomic instability 
Baroreceptor dysfunction 
Cerebrovascular
Vertebrobasilar insufficiency
Subclavian steal syndrome
Aortic dissection
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6
Q

List some non-syncopal causes of blackout.

A

Intoxication
Head trauma
Psychogenic (non-epileptic)
Epileptic seizure

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7
Q

What is the most common cause of blackout in:
Young
Middle-aged
Elderly

A 
The young
Vasovagal
The middle-aged
Vasovagal + arrhythmia
The elderly
Postural hypotension
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8
Q

Which classes of medications are commonly associated with orthostatic hypotension?

A 
ACE inhibitors
Diuretics 
Beta-blockers
Alpha-blockers
CCBs
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9
Q

List three questions that are important to ask about the event preceding the blackout.

A

Was there any WARNING?
Were there any PRECIPITATING FACTORS?
Was there any HEAD TRAUMA?

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10
Q

Which causes of collapse may be associated with symptoms preceding collapse?

A

Epileptic seizure – patients may experience a prodromal aura

Vasovagal – patients may experience vagal symptoms (e.g. sweating, pallor, nausea, dizziness)

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11
Q

Which causes of collapse tend to occur with no warning?

A

Cardiac causes

NOTE: arrhythmias may cause preceding palpitations

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12
Q

List some factors that may precipitate collapse and state the underlying cause of collapse that they are associated with.

A

Standing up – postural hypotension
Exercise – cardiac pathology (e.g. aortic stenosis, HOCM, long QT)
Head turning – carotid body hypersensitivity
Vigorous arm activity – subclavian steal syndrome
Vasovagal has many precipitants (e.g. fear, heat, standing for a long time)

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13
Q

List two questions that are important to ask about what happened during the collapse.

A

HOW LONG did the blackout last?

Was there any TONGUE-BITING, MOVEMENT OF LIMBS or INCONTINENCE of urine or faeces?

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14
Q

What feature of the collapse is pathognomonic with an epileptic seizure?

A

Tongue-biting

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15
Q

What question is important to ask about the state of the patient after the collapse?

A

Did the patient RECOVER SPONTANEOUSLY or were they CONFUSED afterwards?

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16
Q

List five key components that should be explored in the patient’s past medical history.

A 
Previous episodes of collapse 
Diabetes 
Cardiac illness
Peripheral vascular disease (ask about intermittent claudication because they may not have had a PVD diagnosis)
Epilepsy
Anaemia
Psychiatric illness
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17
Q

List some important features of the drug history that help narrow the differential for collapse.

A

Insulin and other hypoglycaemics
Antihypertensives
Vasodilators
Anti-arrhythmics (paradoxically predisposes to arrhythmia)
Antidepressants (hypotension may be a side effect)
Warfarin and other anticoagulants

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18
Q

List some important features of the social history.

A

Alcohol

Use of stimulant recreational drugs (e.g. cocaine) – can cause tachyarrhythmia and drop cardiac output

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19
Q

What key question must be asked about the family history of the patient?

A

Have you had any close relatives who have died suddenly below the age of 65?

20
Q

List some key features of general examination that allow narrowing of the differential diagnosis.

A

Tongue-biting
Dehydration
Head trauma

21
Q

List some features of the cardiovascular examination that may indicate a cardiac cause of collapse.

A

Irregular pulse – AF
Ejection-systolic murmur – aortic stenosis
Carotid bruits – carotid artery stenosis

22
Q

What test is important to perform in order to check for orthostatic hypotension?

A

Lying/standing blood pressure

23
Q

How is orthostatic hypotension clinically defined?

A

Systolic drop > 20 mm Hg

Diastolic drop > 10 mm Hg

24
Q

Why are focal neurological signs important to pick up?

A

Peripheral neuropathy may be caused by diabetes

Parkinson’s disease can lead to autonomic dysfunction

25
Q

List three important blood investigations that should be performed in a patient with collapse and state the reasons for using them.

A

FBC – anaemia can worsen oxygen starvation of the brain
U&Es – check for biochemical evidence of dehydration + electrolyte abnormalities
Capillary blood glucose – exclude hypoglycaemia + check for undiagnosed diabetes

26
Q

What other investigation is important to perform in a patient with collapse?

A

ECG – check for arrhythmia

NOTE: a normal ECG does not exclude a cardiac cause because arrhythmia may be paroxysmal

27
Q

List three causes of aortic stenosis.

A

Bicuspid aortic valve
Senile calcification
Rheumatic fever

28
Q

Define status epilepticus.

A

Seizures lasting for > 30 mins or repeated seizures without regain of consciousness in between

29
Q

Describe the treatment of status epilepticus.

A

IV benzodiazepines (e.g. lorazepam, buccal midazolam)
If still fitting after 10 mins, repeat IV benzo
If still fitting after 10 mins, consider phenytoin infusion
If still fitting after 10 mins, consider general anaesthesia (e.g. thiopentone)

30
Q

List some potential causes of status epilepticus.

A 
Poor compliance with anti-convulsant medications 
Metabolic (e.g. hypoglycaemia)
Alcohol and other toxins
Hypoxia
Infection
31
Q

What is a Stokes-Adams attack?

A

A sudden transient loss of consciousness induced by a slow or absent pulse and subsequent loss of cardiac output

32
Q

What underlying problems can cause Stokes-Adams attacks?

A

Complete heart block

Sinoatrial disease

33
Q

Define epilepsy.

A

A tendency to recurrent, unprovoked seizures

34
Q

Define seizure.

A

A transient excessive electrical activity with motor, sensory and cognitive manifestations

35
Q

What are the two different types of seizure?

A

Generalised – affecting the whole brain

Partial – affecting a part of the brain

36
Q

What are the subdivisions of generalised seizures?

A

Tonic-clonic – patients are initially rigid and then convulse with rhythmical muscular contractions
Absence – patients loses consciousness and seems vacant and unresponsive (mainly in children)
Atonic – brief loss of muscle tone making the patient fall
Tonic – like the tonic phase of tonic-clonic
Clonic – like the clonic phase of tonic-clonic
Myoclonic – extremely brief muscle contraction seen as jerky movements

37
Q

What are the two different types of partial seizure?

A

Simple Partial – consciousness is UNimpaired

Complex Partial – consciousness is impaired

38
Q

What is the main side-effect of all anti-convulsants?

A

They are ALL TERATOGENIC

39
Q

What birth defects are the following drugs associated with:
Sodium Valproate
Phenytoin

A

Sodium Valproate
Neural tube defects
Phenytoin
Cleft palate + congenital heart disease

40
Q

Describe the effect of carbamazepine and phenytoin on drug metabolism.

A

They are CYP450 inducers

They cause increased metabolism and, hence, reduced effectiveness of OCP and warfarin

41
Q

Which anti-convulsant is associated with Stevens-Johnson syndrome?

A

Lamotrigine

42
Q

List four rare cardiac causes of collapse.

A

HOCM
Long QT Syndrome
Brugada Syndrome
Arrhythmogenic Right Ventricular Dysplasia

43
Q

List two acquired causes of long QT syndrome.

A

Hypomagnesaemia

Hypokalaemia

44
Q

Describe the inheritance pattern of Brugada syndrome.

A

Autosomal dominant

45
Q

What ECG changes are associated with Brugada syndrome?

A

RBBB

Saddle-shaped ST elevation in V1-3

46
Q

What is the main intervention used for patients with these rare causes of collapse?

A

Implantable cardioverter defibrillator (ICD)

Oxford Clinical Cases (28 decks)

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