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Neurology > 1: Disorders Of Consciousness > Flashcards

1: Disorders Of Consciousness Flashcards

1
Q

What are the four disorders of consciousness

A
  • Locked-In
  • Coma
  • Persistent vegetative state
  • Brainstem death
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2
Q

What is a coma

A

State of unarousable consciousness

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3
Q

How is a coma defined

A

E2
V2
M4

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4
Q

What is E2

A

Eyes open to pain

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5
Q

What is V2

A

Sounds

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6
Q

What is M4

A

Flexion (Withdraw) From Pain

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7
Q

What GCS indicates coma and what does this indicates

A

8 - requires intubation

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8
Q

What are the two broad etiological categories for coma

A

Neurological

Metabolic

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9
Q

Give 3 neurological causes of coma

A

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

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10
Q

Give 5 metabolic causes of coma

A 
Hypoxia 
CO poisoning 
Hypoglycaemia
Hypothermia
Septicaemia
Addison's
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11
Q

Explain self-awareness in coma

A

No self-awareness

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12
Q

Explain sleep-wake cycle in coma

A

No sleep-wake

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13
Q

Explain movement in coma

A

No movement

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14
Q

Define consciousness

A

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

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15
Q

What are the two aspects of consciousness

A
  • Awareness

- Arousal

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16
Q

What controls arousal

A

Ascending reticular activating system (RAS) in the brainstem

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17
Q

What controls awareness

A

Cortex

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18
Q

What causes coma

A
  • Bilateral cortical injury (Awareness)

- Reticular Activating System - RAS Injury (Arousal)

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19
Q

Explain approach to someone in a coma

A

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

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20
Q

During history of coma, what may slow shallow breathing indicate

A

Metabolic cause

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21
Q

During history of coma, what may deep rapid breathing mean

A

Metabolic acidosis

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22
Q

During history of coma, what does rapid shallow breathing indicate

A

Brainstem lesion

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23
Q

What is decorticate posture

A

Arms: Flexed
Legs: Extended

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24
Q

What does decorticate posture indicate

A

Damage to cerebral cortex

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25
Q

What is decerebrate

A

Arms: Extended
Legs: Extended

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26
Q

What does decerebrate posture indicate

A

Damage to brain-stem

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27
Q

Define brainstem death

A

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

28
Q

What are three pre-requisites for diagnosing brainstem death

A
  1. No endocrine, metabolic, effect depressant drugs or hypothermia causing it
  2. Known aetiology for reversible damage
  3. Patient being ventilated
29
Q

What is step one for diagnosing brain stem death

A

Ensure dealing with brainstem death, this is either done by:

  1. History - aetiology supports diagnosis
  2. If unclear, use EEG
30
Q

What is step 2 of confirming brainstem death

A

Exclude reversible cause

31
Q

How is intoxication excluded

A

Sufficient period of time since intoxication

32
Q

How is hypothermia excluded

A

Core T above 34

33
Q

How is electrolyte abnormality excluded

A

Electrolytes in-range

34
Q

How is acid-base balanced excluded

A

In-range

35
Q

How is neuromuscular block excluded

A

Deep tendon reflexes present

36
Q

What is step 3 of confirming brainstem death

A

Formal brain-stem testing

37
Q

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

A

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
38
Q

What is the caloric test

A

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

39
Q

Explain motor test

A

Pain to supra-orbital or limbs

40
Q

Explain apnea test

A
  • 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
41
Q

Who can diagnose brainstem death

A

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

42
Q

Legally what are individuals with brainstem death classified as

A

Legally individual is classified as dead

43
Q

Define persistent vegetative state

A

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

44
Q

How is persistent vegetative state commonly referred to

A

awake but not aware

45
Q

What causes persistent vegetative state

A

TBI

Diffuse cerebral hypoxia

46
Q

What are hypoxic causes of PVS

A

MI
Drowning
Strangled

47
Q

What usually precedes persistent vegetative state

A

Coma

48
Q

Explain sleep-wake cycles in PVS

A

Present

49
Q

Explain awareness in PVS

A

Absent

50
Q

How is it known individuals with PVS are not aware

A
  • Unable to respond to external stimuli
  • Unable to communicate
  • Deconjugate eye-movements
51
Q

Explain reflexes in PVS

A

Present

52
Q

What causes PVS

A

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

53
Q

Explain how damage correlates with presentation in CVS

A

Cortex = awareness impaired

RAS intact = sleep-wake, reflexes, respiratory control

54
Q

What is locked-in system

A

Bilateral damage to ventral pons

55
Q

What tracts are disrupted in locked-in syndrome

A

Corticospinal

Corticobulbar

56
Q

What is only function remaining in locked-in syndrome

A

Vertical gaze

57
Q

What region is damaged in locked-in syndrome

A

Bilateral ventral pons

58
Q

What are 4 causes of ventral pontine damage

A
  • Ischaemic
  • Trauma
  • Demyelination
  • Tumour
59
Q

Occlusion of what artery causes ischaemic of ventral PONS

A

Vertebrobasilar arteries

60
Q

What haemorrhagic cause leads to damage to ventral pons

A

Rupture berry aneurysm due to HTN

61
Q

Describe clinical presentation of locked-in syndrome

A
  • Quadriplegia
  • CN Palsy
  • Cheyne-Stokes
  • Consciousness intact
62
Q

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

A

Vertical gaze centre is located in midbrain

Horizontal gaze centre is located in PONS

63
Q

Why is cutaneous sensation intact in locked-in syndrome

A

Spinothalamic tract runs in dorsal PONS

64
Q

What investigations are ordered in locked-in

A

EEG - exclude brainstem death

CT- Identify cause

65
Q

What two conditions can cause demyelination of the PONS

A

Multiple Sclerosis

Central pontine myelinolysis

66
Q

What causes central pontine myelinolysis

A

Replacement sodium too quickly causing an osmotic demyelination

Neurology (26 decks)

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