Persistent Vegetative States

Front 1

What is consciousness?

Back 1

“State of full awareness of the self and oneʼs
relationship to the environment”

Front 2

Describe the two different anatomical regions of consciousness.

Back 2

Front 3

What parts of the brain are responsible for arousal?

Back 3

• Reticular activating system
◦Influence arousal
◦ Rostral midbrain and mid pons
◦ Project to subthalamus, hypothalamus, Thalamus

Front 4

Describe the relationship between arousal and awareness in differing states of consciousness.

Back 4

Front 5

What is the vegetative state?

Back 5

• Complex neurological condition in which
patient appears to be awake but shows no
sign of awareness of themselves or their
environment.

Front 6

What is the minimal consciousness state?

Back 6

• Wakefulness accompanied by inconsistent
but reproducible signs of awareness.
◦Non reflexic response to sensory stimulus.
◦Awareness of self or environment.
◦Language comprehension or expression
◦Visual tracking
◦Lack of object use

Front 7

What are the causes of vegetative state?

Back 7

n.b. common stem of acute brain injury

Front 8

How is PVS diagnosed?

Back 8

• Detailed clinical history
• Repeated observation of spontaneous and
elicited behavior.
• Repeated clinical examination
• Imaging - anatomical = MRI, functional = MRI, PET, diffusion tensor
• EEG based technology

Front 9

What are diagnostic criteria of PVS?

Back 9

• Cycles of eye opening and closing giving
the appearance of sleep wake cycle.
• Complete lack of self or environment.
• Complete or partial preservation of
hypothalamic and brain stem autonomic
functions

Front 10

What electrophysiology can be used to diagnose PVS?

Back 10

• Somato-sensory evoked potentials; absent
predicts VS
• EEG not a good predictor
• ERP predict VS

Front 11

What anatomical correlates are seen in PVS?

Back 11

• Widespread subcortical
white matter
• Thalamus
• Disconnection from
fronto-parietal cortex

Front 12

Describe the cerebral metabolism in varying states of consciousness.

Back 12

Front 13

On an fMRI, what can be used to measure neural activity?

Back 13

Blood Oxygenation Level Dependent (BOLD) signal - Indirect measure of neural activity

neural activity -> ↑ blood oxygen -> ↑ fMRI signal

Front 14

What factors affect recovery from PVS?

Back 14

• Time spent in Vegetative state
• Age
• Type of brain injury

Front 15

What are the factors of chances of recovery?

Back 15

Time inversely proportional to chance of recovery
1m◦42% 3m 27% 6m 12%

Age - younger patient better recovery

Traumatic brain injury better than anoxic