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CR2 > Tutorial #28: Transient Loss of Consciousness > Flashcards

Tutorial #28: Transient Loss of Consciousness Flashcards

1
Q

What is the definition of syncope?

A

TLOC due to cerebral hypoperfusion; it is characterized by a rapid onset, short duration, and spontaneous complete recovery

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2
Q

What is the definition of transient loss of consciousness? How is it different than seizure or syncope?

A

“A state of real or apparent LOC with loss of awareness, characterized by amnesia for the period of unconsciousness, abnormal motor control, loss of responsiveness, and a short duration”
- it is an umbrella term that encompases both seizures (cerebral epileptic event) and syncope (cerebral hypoperfusion event)

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3
Q

At what systolic BP does syncope typically occur?

A

<60 mmHG

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4
Q

What are the mechanisms that cause syncope?

A
  • Fall in total peripheral resistance or
  • Decreased cardiac output
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5
Q

Which of the following can be associated with urinary incontinence?
a. seizures
b. syncope

A

BOTH a) and b)!
But much more commonly with a)- seizures

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6
Q

Which of the following is associated with pallor:
a. seizures
b. syncope

A

b) syncope

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7
Q

Which of the following is associated with cyanosis:
a. seizures
b. syncope

A

a) seizures

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8
Q

Which of the following is commonly caused by a trigger:
a. seizures
b. syncope

A

b) syncope

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9
Q

Which of the following is associated with auras (motor, somatosensory, auditory, or visual phenomena):
a. seizures
b. syncope

A

a) seizures

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10
Q

Which clinical sign is the strongest predictor of a seizure (highest LR+)?

A

Waking up with a tongue bite (specifically, a lateral tongue bite)

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11
Q

What are three main causes of syncope?

A
  1. Reflex syncope (vasovagal, micturition, baroreceptor, etc)
  2. Orthostatic syncope
  3. Cardiac syncope (i.e. arrythmia, ischemia, structural heart disease, etc)
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12
Q

Decribe two efferent mechanisms of reflex syncope

A
  1. increased parasympathetic tone causing reduced heart rate
  2. reduced sympathetic tone causing vasodilation

OVERALL: results in lower blood pressure and cerebral hypoperfusion

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13
Q

List common triggers for reflex syncope (x5)

A
  1. Venous blood pooling from prolonged sitting or standing
  2. Central stimuli (eg, pain, sight of blood, emotional stress)
  3. Visceral stimuli (eg, distended stomach or bladder)
  4. Carotid sinus baroreceptor stimulation (eg, pressure on the neck)
  5. Intracardiac baroreceptor stimulation
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14
Q

What are features of a prodrome associated with reflex syncope?

A
  • Lasts at least 15 seconds
  • Contains some of the following features: fatigue, nausea, sweating, pallor, visual disturbance, abdominal pain, light-headedness.
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15
Q

What are three types of reflex syncope?

A
  1. Vasovagal: mediated by orthostatic stress or psychological stress (pain, fear)
  2. Carotid sinus hypersensitivity: Head turning, shaving, or other pressure on carotid sinus.
  3. Situational: post-prandial, post-exercice, micturition (i.e. urination)
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16
Q

What are positive predictors for reflex syncope?

A
  • Onset <35 years old
  • Previous similar episodes.
  • Provocative circumstances: prolonged standing (37%), hot weather (42%), lack of food (23%), fear (21%), and acute pain (14%), during or after urinating or defecating.
  • It can occur after exercise, whereas DURING exercise is more concerning for cardiac syncope
17
Q

What are the general management strategies for reflex syncope?

A

Avoid provoking factors.

Avoid medications that lower BP.

18
Q

Negative predictors for reflex syncope:

A

abnormal EKG or known structural heart disease, syncope during exertion (reflex syncope can occur on exertion, but this is a red flag for more dangerous causes), long duration of LOC.

19
Q

What is orthostatic hypotension?

A

Inadequate compensation to position changes causes hypotension, especially when standing up.

20
Q

What can cause orthostatic hypotension?

A

hypovolemia, spinal cord injury, neurologic disorders, or medications

21
Q

What classes of medications commonly cause orthostatic hypotension?

A
  • blood pressure medications,
  • nitrates,
  • tricyclic antidepressants
  • alpha blockers (which are used for hypertension, benign prostatic hypertrophy, PTSD, and sometimes for urinary calculi).
22
Q

What range of time can orthostatic hypotension occur after a positional change?

A

Immediately or up to 30 minutes

23
Q

How do you take postural vital signs?

A

Have patient lay down for at least 5 minutes then stand up.

Check blood pressure within the first 30 seconds and again at 3 minutes, as well as at whatever point they’re feeling the most symptomatic

24
Q

What are the postural vital sign cutoffs?

A

At 3 minutes:
- HR increase by ≥30bpm
- SBP decrease ≥20
- DBP decrease ≥10

25
Q

Which type of syncope/presyncope is associated with position change?

A

Orthostatic hypotension

26
Q

How do you manage orthostatic hypotension?

A
  1. Reassess medications
  2. Lifestyle changes: slow position changes; avoid triggers such as fatigue and overeating; eat smaller more frequent meals if symptoms are postprandial; increase salt and water intake
  3. Waist high elastic “stockings” and medications in severe cases.
27
Q

What is cardiogenic syncope?

A

Decreased cardiac output from arrhythmia, ischemia, or obstruction leading to cerebral hypoperfusion.

28
Q

A previously well 19yo male presents with exertional syncope.
What is the most important cause of syncope you should assess for? What do you expect to find on your initial investigations, and what is your confirmatory test?

A

Cardiogenic syncope from hypertrophic cardiomyopathy (HCM).
Your ECG may demonstrate signs of left ventricular hypertrophy (i.e. large QRS voltages)
Confirmatory test is formal echocardiogram.

29
Q

What are positive predictors for cardiogenic syncope?
List 10

A
  • Occurs during exertion (suggests obstruction from aortic stenosis or HCM),
  • Preceded by palpitations,
  • When supine (because other types of syncope usually don’t occur then)
  • Sudden with lack of prodrome,
  • Known cardiac disease
  • Age >65 years old,
  • Meds that prolong QT interval
  • Family history of sudden cardiac death.
  • Elevated troponin
30
Q

What is the type of murmur heard with aortic stenosis?

A

Systolic, crescendo-decrescendo, often radiates to carotids loudest at RUSB, radial pulses often are low amplitude and delayed

31
Q

What is the type of murmur heard with HCM?

A

harsh crescendo-decrescendo but it doesn’t radiate to carotids. The pulse is brisk. Murmur intensifies with valsalva and standing.

32
Q

What EKG abnormalities might suggest a cardiac cause of syncope?

A

<-30 or >100, - Arrhythmias (especially rate <50 or >150),
- Bifascicular or trifascicular block,
- QT >480,
- QRS duration >130 or with pre-excitation pattern,
- Abnormal axis <-30 or >100,
- significant ventricular hypertrophy,
- non-sustained VTach,
- Brugada pattern

33
Q

What initial tests would you order for a patient suspected or having cardiogenic syncope?

A
  • EKG and cardiac monitoring
  • Basic bloodwork including K, Mg, Ca, troponin

Depending on the type of cardiogenic syncope, assessment by cardiology is reasonable to determine admission, role for urgent echo if aortic stenosis or HCM are suspected, monitoring/treatment of arrythmias

34
Q

What are important elements of the history on a patient presenting with TLOC?

A

Step-by-step recount of the event!
- Events leading up to it
- Sensations in the moments before
- How they felt afterwards
- Ask patients if they knew something was about to happen or if they had time to brace themselves before falling.

  • Description of any previous events
  • History of cardiac events, cardiac risk factors
  • Other past medical history and current medication list
  • Family history of sudden cardiac death

Witnesses’ accounts - can confirm patient history, describe the event itself (duration, colour changes, movements, time between first sign of consciousness and return to normal)

35
Q

What are elements of a physical exam that you would look for on a patient presenting with a TLOC?

A

General appearance: level of alertness/GCS

Vital signs including capillary glucose (it counts as a vital sign for any patient with altered LOC).

Postural BP measurements only useful if strongly suspicious of orthostatic hypotension, as sensitivity is poor

Cardiac exam including radial pulses

Neurologic exam if there is suspicion of neurologic cause or if the patient sustained a head injury.

36
Q

What are useful initial investigations for the workup of syncope?

A
37
Q

List RED FLAGS for syncope (history or ECG)

A

CR2 (20 decks)

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