Persistent Vegetative State Flashcards
What is consciousness?
State of full awareness of self and the environment
What are the 2 parts of consciousness?
Arousal - sleep and wake up cycle
Content - sum of all our interactions with environment
What is a vegetative state?
Complex condition
Spontaneous eye-opening signalling wakefulness but no evidence of purposeful behaviour suggesting awareness of self or environment
No purposeful behaviours when exposed to stimuli and no language comprehension or expression
Patient appears to be awake but shows no sign of awareness of themselves/environment
What are the 2 types of vegetative state?
- persistent (persistent for 1 month)
- permanent (12 months after traumatic brain injury, 3 months after non traumatic causes - anoxia/hypoxia)
What are the anatomical correlations of consciousness?
Small region in rostral dorsolateral pontine tegmentum
- connected to 2 cortical regions: ventral anterior insula and pregenual ACC
- disconnection = disorders of consciousness
How is vegetative state diagnosed?
- clinical history
- repeated observation of spontaneous and elicited behaviour
- imaging (anatomical and functional)
- electrophysiology
What do you look for on an electrophysiology?
- absent somato-sensory evoked potentials
- EEG: global slowing
Which anatomical tests do you carry out?
MRI
Which functional tests do you carry out?
PET
MRI - reduction in default mode neurons
Diffusion Tensor Imaging
What do you look for on an observation of spontaneous and elicited behaviour?
Sustained reproducible purposeful or voluntary response to visual/olfactory/auditory/tactile or noxious stimuli
- comprehension of language/expression
How do you assess consciousness?
- Auditory Stimulation
- imaging: PET or blood oxygenation level dependent MRI imaging to see central blood flow associated with brain activity
How can a misdiagnosis occur?
Assessor Factors: lack of training, limited knowledge
Patient Factors: physical disability, visual impairment
What is a minimally conscious state?
wakefulness with inconsistent signs of awareness:
- non-reflexic response to sensory stimulus
- language comprehension/expression
- visual tracking
- appropriate smiling/crying to visual/linguistic stimuli
Akinetic Mutism
What is akinetic mutism?
Awake but diminished drive to respond
- apparent alertness along with lack of almost all motor functions including speech, gestures and facial expression
- often misdiagnosed as depression or delirium
What factors affect recovery?
- time spent in vegetative state (inversely proportional)
- age (younger better)
- type of brain injury (traumatic better outcome than anoxic)
What pharmacological treatment is there?
Amantadine - weak NMDA receptor antagonist and blocks dopaminergic reuptake
Zolpidem - indirect GABAa receptor agonist, ST treatment
What surgical treatment is there?
Central thalamic DBS
What other problems would need supportive treatment?
Spasticity
UTI
Sleep problems
Agitation/hyperkinesia
What is the ethical perspective?
- only made if patient shown to be unaware of self/environment
- stopping artificial nutrition/hydration requires approval of high court
- is continued treatment in patients best interest?
What structures of the brain control consciousness?
Rostral dorsolateral pontine tegmentum connected to 2 cortical regions: ventral anterior insula and pregenual anterior cingulate cortex
What is the function of the pontine tegmentum?
Controls sleep states and levels of arousal and vigilance
What is the seat consciousness?
Lateral prefrontal cortex
Posterior parietal cortex
(responsible for high-level complex thought)
What is the global workspace theory?
We taken on sights/sounds/taste and combine into global workspace, selects all the ones we want filtering it and merge it into a single person object
What can alter consciousness?
Traumatic brain injury
Severe stroke
Haemorrhage
Hypoxia
