Coma, Persistent Vegetative State, Brain Death

Question 1

what is a coma?

Answer 1

A state of unrousable psychological unresponsiveness in which the subjects lie with eyes closed and show no psychologically understandable response to external stimulus or inner need

Question 2

what 2 things does consciousness depend on?

Answer 2

an intact ascending reticular activating system to act as the alerting or awakening element of consciousness

a functioning cerebral cortex of both hemispheres which determines the content of that consciousness

Question 3

what are causes of decreasing GCS?

Answer 3

Toxic/metabolic states
Seizures
Damage to reticular activating system
Causes of raised intracranial pressure

Question 4

what is a persistent vegetative state?

Answer 4

A state in which the brain stem recovers to a considerable extent but there is no evidence of recovery of cortical function

Question 5

what is “Locked-in” Syndrome?

Answer 5

The patient has total paralysis below the level of the third nerve nuclei and, although able to open, elevate and depress the eyes, has no horizontal eye movements and no other voluntary eye movement

Question 6

how does different breathing states give insight to the cause?

Answer 6

Depressed respiration - drug overdose, metabolic disturbance
Increased respiration - hypoxia, hypercapnia, acidosis
Fluctuating respiration - brainstem lesion

Question 7

on resuscitation what investigations should be done?

Answer 7

Blood samples
glucose, biochemistry, haematology, blood gas
toxicology
Examine for evidence of meningitis - treat on suspicion

Question 8

what GCS is regarded as being in a coma?

Answer 8

Eye opening - 2 or less
Verbal response - 2 or less
Motor response - 4 or less
GCS≤8

Question 9

how can the brainstem function be tested?

Answer 9

Pupillary reactions
Corneal responses
Spontaneous eye movements
Oculocephalic responses (Doll’s eye)
Oculovestibular responses
Respiratory pattern

Question 10

how can the motor function be tested?

Answer 10

Motor response
Muscle tone
Tendon reflexes
Seizures

Question 11

what are causes of a coma without focal or lateralising signs and without meningism?

Answer 11

Anoxic/ ischaemic conditions
Metabolic disturbances
Intoxications
Systemic infections
Hyperthermia/ Hypothermia
Epilepsy

Question 12

what are investigations for a coma without focal or lateralising signs and without meningism?

Answer 12

Toxicology screen including alcohol level
Measure blood sugar and electrolytes
Assess hepatic and renal function
Acid - base assessment and blood gases
Measure blood pressure
Consider carbon monoxide poisoning

Question 13

what are causes of a coma without focal or lateralising signs but with meningism?

Answer 13

Subarachnoid Haemorrhage
Meningitis
Encephalitis

Question 14

what are investigations for a coma without focal or lateralising signs but with meningism?

Answer 14

CT head scan

Lumbar puncture
Appearance
Cell count
Glucose level
Capsular antigen tests

Question 15

what are causes of a coma with focal or lateralising signs?

Answer 15

Cerebral tumour
Cerebral haemorrhage
Cerebral infarction
Cerebral abscess

Question 16

what are investigations for a coma with focal or lateralising signs?

Answer 16

CT or MRI obligatory

If CT/MRI not diagnostic, then investigate as for other causes of coma e.g. including
metabolic screens, lumbar puncture, EEG

Question 17

what are “Medical” causes of coma lasting more than 5 hours

Answer 17

40% due to drug ingestion ± alcohol
25% due to hypoxia e.g. secondary to MI
20% due to cerebrovascular event, either haemorrhage or infarction
15% metabolic e.g. diabetes

Question 18

what is the outcome of a non-traumatic coma for more than 6 hours?

Answer 18

15% good or moderate recovery

85% will die, remain vegetative or reach a state of severe disability in which they remain dependent

Question 19

what is the outcome of a non-traumatic coma for less than 6 hours?

Answer 19

good recovery is seen in:
35% of those with underlying metabolic cause
11% of those with hypoxic ischaemic insult
7% of those with cerebrovascular disease

Question 20

how can a head injury lead to focal neurological signs/Epilepsy?

Answer 20

Diffuse axonal injury
Contusion
Intracerebral haematoma
Extra-cerebral haematoma :
-Extra-dural haematoma
-Sub-dural haematoma

Question 21

how is Sub-dural/Extra-dural haematoma seen on a CT?

Answer 21

Subdural haematoma ellipse
convex/convex

Extradural haematoma
concave/convex (lens)

Question 22

how is increased ICP treated?

Answer 22

Surgery to relieve pressure -heamatoma, ventricular shunt
Osmotic agents e.g. mannitol
Nurse with head at 30-45% (Venous return)
Reduce pain
Maintain good PO2, reduce PCO2
Reduce metabolism (reduce temperature, barbiturates)