24.1 Consciousness

Question 1

What is the definition of a coma?

Answer 1

A prolonged state of deep unconsciousness

Question 2

In a graph measuring level of consciousness (wakefulness) against content of consciousness (awareness), where does coma fall compared to other states?

Answer 2

Right at lowest levels of wakefulness and awareness

Question 3

What are some causes of coma?

Answer 3

• Focal lesions: trauma, stroke, tumour, abscess
• Drugs, toxins
• Seizures
• Systemic infection
• Endocrine issues: diabetes, thyroid, adrenal
• Meningitis
• Encephalitis
• Demyelination (e.g. MS)

Question 4

Which cause of coma accounts for 40% of cases?

Answer 4

Drug poisoning

Question 5

Which cause of coma accounts for 25% of cases?

Answer 5

Lack of oxygen (hypoxia) - usually from cardiac arrest

Question 6

What is the difference between brain death and the vegetative state?

Answer 6

A vegetative state is potentially reversible while brain death is not

Question 7

What is a persistent vegetative state?

Answer 7

A persistent vegetative state is a disorder of consciousness caused by severe and irreversible brain damage12. A person in this state has lost their thinking abilities and awareness of their surroundings, but retains some non-cognitive functions and normal sleep pattern

Question 8

What cause of coma accounts for 20% of cases?

Answer 8

Stroke

Question 9

What cause of coma accounts for 15% of cases?

Answer 9

Trauma: blood loss, malnutrition, hypothermia, etc

Question 10

What is a minimally conscious state?

Answer 10

Minimally conscious state (MCS) is defined as a condition of severely altered consciousness in which minimal but definite behavioural evidence of self or environmental awareness is demonstrated.