Coma

Question 1

What are the 2 components of consciousness?

Answer 1

arousal
awareness

coma = not aware and not awake

Question 2

What parts of the brain are arousal and awareness dependent on?

Answer 2

arousal = dependent on reticular activating syndrome (RAS) and diencephalon

awareness = mediated by cerebral cortex

Question 3

What GCS might require intubation?

Answer 3

GCS<8 (coma)

Question 4

What scale assesses conscious level?

Answer 4

GCS (glasgow coma scale)

Question 5

What causes neurogenic respiration?

Answer 5

any cause of metabolic acidosis:
- renal failure
- DKA
- aspirin overdose
- ethylene glycol poisoning

Question 6

What causes hypoventilation?

Answer 6

drugs:
- opiates
- benzodiazepines
- barbiturates

Question 7

What can cause myoclonus in a comatose patient?

Answer 7

usually hypoxic cortical injury

Question 8

Coma mimics

Answer 8

locked-in syndrome
psychiatric unresponsiveness

Question 9

What are 3 categories of coma?

Answer 9

coma with no focal signs or meningism
coma with meningism but no focal signs
coma with focal signs

Question 10

What causes coma with no focal signs or meningism?

Answer 10

results from neuronal depression due to intoxication, acute metabolic or endocrine derangement

• hypoxic
• metabolic
• toxic and drug-induced
• infections
• post-seizure states

Question 11

What causes coma with meningism but no focal signs?

Answer 11

meningitis (meningoencephalitis)
subarachnoid haemorrhage

Question 12

What causes coma with focal signs?

Answer 12

due to structural brain injury affecting:
- ascending reticular activating system in dorsal pons + midbrain
- both thalami
- bilateral cortex or white-matter connections to the cortex

• intracranial haemorrhage
• infarction
• tumour
• abscess

Question 13

Symptoms of raised ICP

Answer 13

headache
vomiting
progressive drowsiness

Question 14

Management of acute supratentorial mass with brain shift - raised ICP

Answer 14

intubation + mechanical ventilation

correct hypoxaemia/hypercapnia

elevate head to 30 degrees

treat extreme agitation with lorazepam 2mg IV or propofol

mannitol 20%, 1g/kg

dexamethasone, 100mg IV (tumours only)

Question 15

When should a head CT be performed within 1 hour in head injuries?

Answer 15

within 1 hour if any of:
- GCS <13/15 on A&E assessment
- GCS <15/15, 2 hours after injury
- suspected skull #
- focal neurological deficit
- any sign of basal skull # (haemotypanum, panda eyes, CSF leak from nose/ears, Battle’s signs)
- post-traumatic seizure
- >1 vomiting episode

Question 16

When should a head CT be performed within 8 hours in head injuries?

Answer 16

• on anticoagulants with evidence of head injury
• any LOC or amnesia since injury and one of: retrograde amnesia >30mins, clotting or bleeding disorder, age>65
• dangerous mechanism of injury (fall from >1m or 5 stairs, pedestrian/cyclist hit by motor vehicle, ejection from motor vehicle)

Question 17

Principles of management of patients in a coma

Answer 17

ensure oxygenation
maintain circulation
control glucose
lower ICP
stop seizures
treat infection
restore acid-base and electrolyte balance
adjust body temperature
administer thiamine
consider specific antidotes
control agitation