23. Persistant vegetative states

Question 1

Define consciousness

Answer 1

State of awareness of the self and one’s relationship to the environment

Question 2

What are the different components making up consciousness?

Answer 2

Arousal - sleep/wake cycle

And the total sum of our interactions with the environment

Question 3

What is ‘locked-in syndrome’?

Answer 3

This is a state of full body paralysis but the patient is still conscious
There is complete paralysis of the voluntary muscles (sometimes but often apart from the eyes) so the patient cannot move or communicate but they are aware and cognitively functioning
Often occurs due to a lesion in the region of the pons

Question 4

What is the Glasgow coma scale and what is it used for?

Answer 4

Neurological scale to give a reliable and objective way to record the conscious state of an individual
It is used to asses the level of consciousness by first responders, nurses, doctors and also in intensive care
Records the level of eye, verbal and motor responses

Question 5

Which region of the brain is responsible for consciousness?

Answer 5

There are a group of neurones in the core of the brainstem i.e. in the midbrain and pons and these are responsible for consciousness - damage to these will result in the patient going into a chronic coma and they will never wake up

Question 6

a

Answer 6

a

Question 7

Where do these neurones project to?

Answer 7

These project to variable regions within the brain - subthalamus, hypothalamus, thalamus, basal forebrain

Question 8

What neurotransmitters do these neurones use?

Answer 8

These neurones are heterotropic i.e. they use different neurotransmitters
They may be cholinergic, noradrenergic and orexinergic

Question 9

What is meant by ‘wakefulness’?

Answer 9

This is the most basic form of consciousness - if you are wakeful and aware, then you are conscious

Question 10

What is the vegetative state?

Answer 10

This is a complex neurological condition in which the patient appears to be awake but shows no signs of awareness of themselves or their environment

Question 11

Describe the state of a vegetative patient

Answer 11

These patients have full arousal but they do not have any wakefulness
SO their eyes can be open and they look like they are awake but they are not aware of their surroundings and no not interact - there are no small or minimal motor movements

Question 12

What is the minimal consciousness state?

Answer 12

This is a level of wakefulness accompanied by inconsistent but reproducible signs of awareness

Question 13

Describe the state of a patient in a minimal consciousness state

Answer 13

These patients will have some degree of awareness - will have a slight response to sensory stimulus e.g. may be able to move their hand, smile, cry, mumble etc
The most common motor movement in these patients is eye tracking - tracking people that are in the room

Question 14

What is akinetic mutism and how does it occur?

Answer 14

This is where there is damage to the cingulate gyrus in the frontal lobe i.e. the white matter
In this case, people lack the motivation to respond to anything - can talk or move normally if it is imperative but otherwise lack the motivation to do so

Question 15

Describe the progression from a coma to a permanent vegetative state

Answer 15

Coma - temporary state of unconsciousness lasting for 2/3 weeks
Vegetative state - if have been in a coma for longer than 2/3 weeks
Persistent vegetative state - if been in a vegetative state for more than a month
Permanent vegetative state - if been in a persistent vegetative state for more than 6 months (or 12 months if suffered major trauma)

Question 16

What is the significance of being in a permanent vegetative state?

Answer 16

In this instance, it is very unlikely that the patient will recover from this state especially the longer that they have been in this state for

Question 17

What is the cause for vegetative states?

Answer 17

There are a wide range of causes

Generally this occurs due to some form of trauma but may also occur due to a level of chronic neurodegeneration

Question 18

Give the anatomical structures in which damage could result in a patient being in a vegetative state

Answer 18

Medial prefrontal cortex
Thalamus (especially central thalamus)
Inferior parietal lobe (especially where it meets the temporal lobe)
Basal ganglia

Question 19

How is the vegetative state diagnosed?

Answer 19

History
Imaging
Electrophysiology (lesser degree)

Use examinations to assess all of the senses - visual, olfactory, auditory, tactile or noxious
To also get a sense of the their comprehension of language or expression

Question 20

What is the diagnostic criteria for a vegetative state?

Answer 20

Cycles of eye opening and closing giving the appearance of a sleep wake cycle
Complete lack of self or environment
Complete or partial preservation of hypothalamic and brainstem autonomic functions

Question 21

What types of imaging is used to assess a vegetative state?

Answer 21

Electophysiology

MRI

Question 22

How is electrophysiology used to asses a vegetative state?

Answer 22

EEG - electrodes on head, measure the electrical activity of the brain
Event related potentials (ERP) - put headphones onto the patient, they listen to sounds and you look for responses from the patient

Question 23

How is MRI used to asses a vegetative state?

Answer 23

MRI used for anatomical imaging to look at any abnormal calcifications or neuronal swellings/extracellular swellings
OR used for functional imaging - can see which area of the brain is activated in particular as the metabolism increases

Question 24

What are the different factors that can affect the recovery of a patient in a vegetative state?

Answer 24

Time spent in this state - the longer you spend in this state, the less likely you are to recover
Age - younger patients are more likely to recover as they have a much greater level of neuronal plasticity
The type of brain injury that has occurred - hypoxic brain injuries do not tend to do well

Question 25

What are the different treatment options for these patients?

Answer 25

Pharmacological
Surgical
Supportive

Question 26

How is a patient represented ethically and legally when in a vegetative state and how does a court make a decision on their outcome?

Answer 26

Represented legally by an official solicitor

The question of the court is whether continued treatment will be in the patient’s best interests