1: Disorders Of Consciousness

Question 1

What are the four disorders of consciousness

Answer 1

• Locked-In
• Coma
• Persistent vegetative state
• Brainstem death

Question 2

What is a coma

Answer 2

State of unarousable consciousness

Question 3

How is a coma defined

Answer 3

E2
V2
M4

Question 4

What is E2

Answer 4

Eyes open to pain

Question 5

What is V2

Answer 5

Sounds

Question 6

What is M4

Answer 6

Flexion (Withdraw) From Pain

Question 7

What GCS indicates coma and what does this indicates

Answer 7

8 - requires intubation

Question 8

What are the two broad etiological categories for coma

Answer 8

Neurological

Metabolic

Question 9

Give 3 neurological causes of coma

Answer 9

Infection (Encephalitis, Meningitis)
Trauma
Seizures: non-convulsive SE

Question 10

Give 5 metabolic causes of coma

Answer 10

Hypoxia 
CO poisoning 
Hypoglycaemia
Hypothermia
Septicaemia
Addison's

Question 11

Explain self-awareness in coma

Answer 11

No self-awareness

Question 12

Explain sleep-wake cycle in coma

Answer 12

No sleep-wake

Question 13

Explain movement in coma

Answer 13

No movement

Question 14

Define consciousness

Answer 14

Awareness of self and environment, with ability to respond appropriately to stimuli

Question 15

What are the two aspects of consciousness

Answer 15

• Awareness

- Arousal

Question 16

What controls arousal

Answer 16

Ascending reticular activating system (RAS) in the brainstem

Question 17

What controls awareness

Answer 17

Cortex

Question 18

What causes coma

Answer 18

• Bilateral cortical injury (Awareness)

- Reticular Activating System - RAS Injury (Arousal)

Question 19

Explain approach to someone in a coma

Answer 19

A-E
Intubate if GCS less than-8
Treat cause

Question 20

During history of coma, what may slow shallow breathing indicate

Answer 20

Metabolic cause

Question 21

During history of coma, what may deep rapid breathing mean

Answer 21

Metabolic acidosis

Question 22

During history of coma, what does rapid shallow breathing indicate

Answer 22

Brainstem lesion

Question 23

What is decorticate posture

Answer 23

Arms: Flexed
Legs: Extended

Question 24

What does decorticate posture indicate

Answer 24

Damage to cerebral cortex

Question 25

What is decerebrate

Answer 25

Arms: Extended Legs: Extended

Question 26

What does decerebrate posture indicate

Answer 26

Damage to brain-stem

Question 27

Define brainstem death

Answer 27

Loss of capacity for consciousness and irreversible lock of capacity to breathe spontaneously

Question 28

What are three pre-requisites for diagnosing brainstem death

Answer 28

1. No endocrine, metabolic, effect depressant drugs or hypothermia causing it 2. Known aetiology for reversible damage 3. Patient being ventilated

Question 29

What is step one for diagnosing brain stem death

Answer 29

Ensure dealing with brainstem death, this is either done by: 1. History - aetiology supports diagnosis 2. If unclear, use EEG

Question 30

What is step 2 of confirming brainstem death

Answer 30

Exclude reversible cause

Question 31

How is intoxication excluded

Answer 31

Sufficient period of time since intoxication

Question 32

How is hypothermia excluded

Answer 32

Core T above 34

Question 33

How is electrolyte abnormality excluded

Answer 33

Electrolytes in-range

Question 34

How is acid-base balanced excluded

Answer 34

In-range

Question 35

How is neuromuscular block excluded

Answer 35

Deep tendon reflexes present

Question 36

What is step 3 of confirming brainstem death

Answer 36

Formal brain-stem testing

Question 37

How many steps are there to formally diagnose brainstem death and what are they

Answer 37

6-steps: 1. Pupils fixed, non-responsive to light 2. Absent corneal reflex 3. Caloric test 4. No motor response 5. No Gag reflex 6. Apnoea test

Question 38

What is the caloric test

Answer 38

50ml ice-cold water injected into the ear - there should be no eye-movements observed (Loss oculovestibular reflex)

Question 39

Explain motor test

Answer 39

Pain to supra-orbital or limbs

Question 40

Explain apnea test

Answer 40

- Ensure patient on ventilator has sufficient oxygen so PaCO2 is less than 6kPa - Gradually reduce RR - causing pCO2 to rise to more than 6.5kPa - Turn off the ventilator and put patient on 6L oxygen - Wait 5-minutes to see if patient takes a breathe - Take ABG. Rise in pCO2 is a positive test as it indicates individual has not breathed

Question 41

Who can diagnose brainstem death

Answer 41

Two doctors experienced in diagnosing brainstem death with over 5-years postgraduate experience. One must be a consultant. Neither can be attached to transplant team

Question 42

Legally what are individuals with brainstem death classified as

Answer 42

Legally individual is classified as dead

Question 43

Define persistent vegetative state

Answer 43

cortex is impaired,, however, brainstem functions are preserved for more than one month

Question 44

How is persistent vegetative state commonly referred to

Answer 44

awake but not aware

Question 45

What causes persistent vegetative state

Answer 45

TBI | Diffuse cerebral hypoxia

Question 46

What are hypoxic causes of PVS

Answer 46

MI Drowning Strangled

Question 47

What usually precedes persistent vegetative state

Answer 47

Coma

Question 48

Explain sleep-wake cycles in PVS

Answer 48

Present

Question 49

Explain awareness in PVS

Answer 49

Absent

Question 50

How is it known individuals with PVS are not aware

Answer 50

- Unable to respond to external stimuli - Unable to communicate - Deconjugate eye-movements

Question 51

Explain reflexes in PVS

Answer 51

Present

Question 52

What causes PVS

Answer 52

Bilateral diffuse damage to white matter of cerebral cortex. Reticular activating system (RAS) of the brainstem is intact

Question 53

Explain how damage correlates with presentation in CVS

Answer 53

Cortex = awareness impaired RAS intact = sleep-wake, reflexes, respiratory control

Question 54

What is locked-in system

Answer 54

Bilateral damage to ventral pons

Question 55

What tracts are disrupted in locked-in syndrome

Answer 55

Corticospinal | Corticobulbar

Question 56

What is only function remaining in locked-in syndrome

Answer 56

Vertical gaze

Question 57

What region is damaged in locked-in syndrome

Answer 57

Bilateral ventral pons

Question 58

What are 4 causes of ventral pontine damage

Answer 58

- Ischaemic - Trauma - Demyelination - Tumour

Question 59

Occlusion of what artery causes ischaemic of ventral PONS

Answer 59

Vertebrobasilar arteries

Question 60

What haemorrhagic cause leads to damage to ventral pons

Answer 60

Rupture berry aneurysm due to HTN

Question 61

Describe clinical presentation of locked-in syndrome

Answer 61

- Quadriplegia - CN Palsy - Cheyne-Stokes - Consciousness intact

Question 62

Why is vertical. but not horizontal eye movement, in tact

Answer 62

Vertical gaze centre is located in midbrain | Horizontal gaze centre is located in PONS

Question 63

Why is cutaneous sensation intact in locked-in syndrome

Answer 63

Spinothalamic tract runs in dorsal PONS

Question 64

What investigations are ordered in locked-in

Answer 64

EEG - exclude brainstem death | CT- Identify cause

Question 65

What two conditions can cause demyelination of the PONS

Answer 65

Multiple Sclerosis | Central pontine myelinolysis

Question 66

What causes central pontine myelinolysis

Answer 66

Replacement sodium too quickly causing an osmotic demyelination