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Week 232 - Epilepsy > Coma > Flashcards

Coma Flashcards

1
Q

Define Coma

A

A state of unrousable unconsciousness

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2
Q

Define arousal

A

Level of consciousness/alertness

- the function of reticular activating system in pons and midbrain and its interaction with the thalamus

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3
Q

Define awareness

A

Content of counsciousness

  • awareness of self environment
  • function of multiple cortical areas
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4
Q

What are the four general causes of coma?

A

Massive cortical damage

Brainstem lesion

Brainstem compression

Diffuse physiological brain dysfunction

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5
Q

What is massive cortical damage?

A

Extensive damage to the brain cerebral cortex and cortical connections

  • unilateral
  • bilateral
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6
Q

What are the causes of unilateral cortical damage?

A

Large expanding mass lesions which causes increased ICP

e.g. haemorrhage, large middle cerebral artery infarct

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7
Q

What are the causes of bilateral cortical damage?

A 
Subarachnoid haemorrhage
Encephalitis
Diffuse brain injury
Acute hydrocephalus
Diffuse cerebral oedema
Hypoxic-ischaemic encephalopathy
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8
Q

What is a brainstem lesion?

A

A structural injury to the brainstem or thalamus, e.g.

  • bilateral thalamic lesions
  • ischaemia
  • tumour
  • haemorrhage
  • stroke
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9
Q

What is a brainstem compression?

A

A supratentorial mass lesion within the brain compresses the brainstem inhibiting the ascending reticular activating system
e.g. coning from a brain tumour or haemorrhage

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10
Q

What is diffuse physiological brain dysfunction?

A

Generalised severe metabolic/toxic disorders depress cortical and ARAS function, e.g.

  • Hypothermia
  • Sudden hypertension
  • Prolonged status epilepticus
  • Drugs, toxins, poisonings
  • Psychiatric
  • Metabolic = derranged Na, raised Ca, derranged glucose, renal failure, hepatic failure
  • Endocrine = hypothyroidism, Addison’s, Pan-hypopituitarism
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11
Q

What are the most common causes of coma?

A

Metabolic disorders (35%)

Drugs and toxins (25%)

Mass lesions (20%)

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12
Q

Name two important coma mimicks

A

Locked in syndrome

Psychogenic coma

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13
Q

What is locked in syndrome?

A

De-efferented motor tracts, leads to:

Complete paralysis except blinking and vertical eye movements intact in ventral pontine infarction

Awareness and arousal retained

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14
Q

Describe the immediate management of coma

A

ABC

  • intubate if necessary
  • improve oxygen sats and correct BP
  • warm up/cool down

Blood glucose if hypoglycaemic

Treat seizures with buccal medazolam

IV Abx if fever and meningism

Antidote if OD, or thiamine if Wernicke’s encephalopathy

Treat underlying cause

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15
Q

When is the neurological assessment of a coma patient not reliable?

A

If they:

  • are metabolically derranged
  • are hypothermic
  • have sedative drugs in their circulation
  • have an endocrine disturbance
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16
Q

What four specific things are involved in the neurological examination?

A

Meningism signs

Fundi

Brainstem function
- pupils; eye movements and position; other reflexes;

Lateralising signs

17
Q

What does a dilatation of one fixed pupil mean?

A

Compression of CN III - surgical emergency

18
Q

What does bilateral mid-point reactive pupils (normal) mean in coma?

A

Sedative drugs that are not opiates

19
Q

What does bilateral light-fixed dilated pupils mean?

A

Sign of brain death
- occur in deep coma of any cause, particularly:
> barbiturate intoxication
> hypothermia

20
Q

What does bilateral pinpoint, light-fixed pupils mean?

A 
Pontine lesions (e.g. haemorrhage), or
Opiates
21
Q

What are dysconjugate eyes and what are they a sign of?

A

Divergent ocular axes
- e.g. skew deviation (one eye up, one eye down)

Sign of Brainstem lesion

22
Q

What is conjugate daze deviation a sign of?

A

Towards the lesion in frontal lobe and the normal limbs
=> intact side pushing eyes away

Away from lesion in brainstem towards weak limbs
=> PPRF in pons controls lateral gaze ipsilaterally

23
Q

What is the oculocephalic response (vestibulo-ocular reflex)?

A

Normally, passive head turning produces conjugate ocular deviation away from direction of rotation

Dissapears in: deep coma, brainstem lesions, brain death

24
Q

What other brainstem reflexes can be tested?

A

Corneal reflex

Cough/gag reflex

Respiratory drive - hypercapnia

25
Q

What lateralising signs can be looked out for?

A

Asymmetry of response to visual threat

Asymmetry of face

Asymmetry of tone

Asymmetry of decerbrate and decorticate posturing

Asymmetrical response to painful stimuli

Asymmetry of tendon reflexes and plantar response

26
Q

Which form of imaging is best at revealing a midbrain/brainstem lesion, white matter disease or encephalitis?

A

MR

27
Q

Which form of imaging is best at detecting a basillar artery thrombosis?

A

MR angiogram or CT angiogram

28
Q

What is CT scan good at?

A

Quick and easy, will reveal blod or large hemisphere lesion

29
Q

When is a Lumbar puncture indicated in coma?

A

When imaging is normal and no cause for coma

30
Q

What are the outcomes of Coma?

A

Regain Consciousness

  • Minimally conscious
  • Dependant
  • Good recovery

Persistent Vegatative State

Death

Week 232 - Epilepsy (3 decks)

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