Consciousness Flashcards
What is consciousness?
The state of wakefulness and awareness of self and environoment
Wakefulness
a sleep wake cycle, eyes open, motor activity
Awareness
knowing one exists, the feeling of I am, the mind’s a subjective experience
Coma is a state of
unrousable unresponsiveness lasting for more than 6 hours
What constitutes consciousness:
- brain arousal/activation: eyes open, motor
arousal - connected thought patterns
- ability to sense sensory inputs: external,
interoception (sense of internal state of the
body), emotion - ability to affect controlled outputs: motor,
attention, cognition, emotional
Interoception is located in
the anterior insular cortex and von economo neurons
Different States of Consciousness:
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Coma:
- pathological
- fails to respond normally to painful stimuli,
light or sound - lacks a normal sleep-wake cycle
- does not initiate voluntary actions
- eyes are usually controlled: visual threat,
pupillary reactions - may be reversible or irreversible
Causes of Impaired Consciousness:
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hypoglycaemia = not enough glucose
dka = hyperglycaemia
Tools to Measure Consciousness:
- glasgow coma scale
- mmse
- alert, verbal, pain, unresponsive AVPU
- the 4As Test
Most coma tools are
sensori-motor stimulus and response tests
Glasgow Coma Scale:
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Never have less than 3; even if dead
GCS<8 is concerning because
can not protect their airway
correlated with outcome in brain injury
MMSE, CAM, 4As Test overview:
- multiple questionnaires used to measure
cognitive impairment, screen for dementia,
delirium and confusion - longer than GCS and AVPU but can be
performed easily at bedside
Questions to consider when seeing a confused patient:
- acute or chronic?
- fluctuations?
- agitation?
- hyperactive, hypoactive or mixed?
- therapeutic interventions have any effect?
Blackout and syncope are a transient loss of
consciousness
Global Neuronal Workspace:
particular type of information processing whereby multiple cognitive systems have simultaneous access to the same information
Blackout and Syncope:
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What structures of the brain correlate to conscious experiences?
- cerebral cortex, posterior cortical hot zone
- parietal, occipital and temporal regions
Integrated Information Theory
consciousness is a product of the highly complex and integrated nature of the brain’s structure
What is the highlighted area referred to as?
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Veon Economo Neurons:
- found in anterior insular cortex in humans,
apes etc - specific neuronal component of
consciousness
Claustrum:
- most densely connected structures in the
brain - specific component of consciousness
Intralaminar Thalamic Nuclei:
- general anesthetics suppress activity in this
region - specific component of consciousness
Reticular Activating System:
- located in the brain stem
- regulates sleep-wake cycles and behaviour
- specific component of consciousness
Minimally Conscious State:
- wakeful (preserved sleep/wake cycle) with
minimal awareness - inconsistent but reproducible responses
Vegetative State:
- wakefulness with absent awareness
- capacity for spontaneous or stimulus-
induced arousal evidenced by a rang of
reflexive and spontaneous behaviours
Locked in Syndrome
- loss of voluntary control of movement
- normal wakefulness and awareness
- conscious but unable to respond
Brainstem Death
- permanent and irrevocable loss of all
brainstem functions - confirmed by the absence of brainstem
reflexes: pupils, cornea, gag, oculovestibular - equated to death of an individual
- if any are present then the person is not
dead
Pre-conditions:
- cause of coma must be established as
irreversible and structural
- deep coma, apnoeic and ventilation
dependent
- pharmacological causes of the above
must be excluded
- reversible causes of coma (temp) must
be excluded
