Consciousness Flashcards
Definition of consciousness
The state of being aware of and responsive to one’s surroundings
Key aspects and requirements of human consciousness
Arousal
Input
Output/ control
- motor
- cognitive
Emotional system
Sleep
Decreased arousal
Physiological
Active process
Reversible and cyclical
Coma definition
Characterised by complete loss of wakefulness and reactivity
A state of unresponsiveness to external stimuli with eyes closed
Coma
Pathological but usually reversible
Causes of coma
Sedation/ anaesthesia
Epilepsy
Electrolyte/ metabolic disturbance
Disturbance of thermoregulation
Structural damage to brainstem/ thalamus/ cortex
- stroke
- trauma
- tumour
- inflammation
- infection
Outcome of coma
Reversal and recovery
Survival into vegetative state or minimally conscious state
Irreversible cessation of function of
- brainstem
- cerebral cortex
- body
Vegetative state
Absent awareness
Preserved arousal
No voluntary response to environment
Variably preserved reflex responses to environment
Causes of vegetative state
Widespread damage to cerebral cortex
- anoxia
- head injury
Continuing vegetative state
4 weeks
Permanent vegetative state
After non-traumatic brain injury
- 6 months in UK
- 3 months in US
After traumatic brain injury
- 1 year
Unresponsive wakefulness syndrome
Proposed by the European Task Force on disorders of consciousness
Yet to be fully defined
Minimally conscious state
Like vegetative state but with at least 1/11 item
- consistent movement to command
- reproducible movement to command
- object recognition
- object localisation
- reaching
- visual pursuit
- fixation
- automatic motor response
- object manipulation
- localisation to noxious stimulation
- intelligible but non-functional verbalisation
Locked in syndrome
Conscious (aroused and aware)
Unable to respond (de-effected)
Most cases are partially locked in
- preserved vertical eye movements
- reserved eye opening
Causes of locked in syndrome
Ventral pontine damage
Severe guillain barre syndrome
