Tutorial #28: Transient Loss of Consciousness

Question 1

What is the definition of syncope?

Answer 1

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

Question 2

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

Answer 2

“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)

Question 3

At what systolic BP does syncope typically occur?

Answer 3

<60 mmHG

Question 4

What are the mechanisms that cause syncope?

Answer 4

• Fall in total peripheral resistance or
• Decreased cardiac output

Question 5

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

Answer 5

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

Question 6

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

Answer 6

b) syncope

Question 7

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

Answer 7

a) seizures

Question 8

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

Answer 8

b) syncope

Question 9

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

Answer 9

a) seizures

Question 10

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

Answer 10

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

Question 11

What are three main causes of syncope?

Answer 11

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

Question 12

Decribe two efferent mechanisms of reflex syncope

Answer 12

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

OVERALL: results in lower blood pressure and cerebral hypoperfusion

Question 13

List common triggers for reflex syncope (x5)

Answer 13

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

Question 14

What are features of a prodrome associated with reflex syncope?

Answer 14

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

Question 15

What are three types of reflex syncope?

Answer 15

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)

Question 16

What are positive predictors for reflex syncope?

Answer 16

• 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

Question 17

What are the general management strategies for reflex syncope?

Answer 17

Avoid provoking factors.

Avoid medications that lower BP.

Question 18

Negative predictors for reflex syncope:

Answer 18

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.

Question 19

What is orthostatic hypotension?

Answer 19

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

Question 20

What can cause orthostatic hypotension?

Answer 20

hypovolemia, spinal cord injury, neurologic disorders, or medications

Question 21

What classes of medications commonly cause orthostatic hypotension?

Answer 21

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

Question 22

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

Answer 22

Immediately or up to 30 minutes

Question 23

How do you take postural vital signs?

Answer 23

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

Question 24

What are the postural vital sign cutoffs?

Answer 24

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

Question 25

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

Answer 25

Orthostatic hypotension

Question 26

How do you manage orthostatic hypotension?

Answer 26

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.

Question 27

What is cardiogenic syncope?

Answer 27

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

Question 28

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?

Answer 28

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.

Question 29

What are positive predictors for cardiogenic syncope? List 10

Answer 29

- 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

Question 30

What is the type of murmur heard with aortic stenosis?

Answer 30

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

Question 31

What is the type of murmur heard with HCM?

Answer 31

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

Question 32

What EKG abnormalities might suggest a cardiac cause of syncope?

Answer 32

<-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

Question 33

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

Answer 33

- 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

Question 34

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

Answer 34

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)

Question 35

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

Answer 35

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.

Question 36

What are useful initial investigations for the workup of syncope?

Answer 36

Question 37

List RED FLAGS for syncope (history or ECG)

Answer 37