Consciousness Flashcards
What is consciousness?
Ability to respond to stimuli Ability to spontaneously move Ability to speak Ability to orientate in time and space The experience of emotion The experience of sensory stimuli The experience of memory The experience of self and non-self
List some key aspects and requirements of human consciousness
Arousal
Input - sense organs, proprioception, interoception and emotion
Output / control - motor and cognitive
Emotional system
List some physiological and pathological states of conciousness
Sleep Coma Death PVS MCS Locked in Syndrome
Describe sleep
Decreased arousal (and hence awareness & therefore consciousness) Physiological Active process Reversible & Cyclical
Describe coma
Characterised by complete loss of wakefulness and reactivity
A state of unresponsiveness to external stimuli with eyes closed
Pathological but usually reversible
Prolonged Unconsciousness
What are the causes of coma?
Sedation / anaesthesia Epilepsy Electrolyte / metabolic disturbance Disturbance of thermoregulation Structural damage to brainstem / thalamus / cortex Stroke Trauma Tumour Inflammation Infection
What are the causes of metabolic coma?
hepatic uraemia diabetic pancreatic adrenocortical failure
List the outcomes of coma
Reversal and recovery Survival into vegetative state or minimally conscious sate Irreversible cessation of function of Brainstem (brainstem death) Cerebral cortex (neocortical death) Body
Describe the glasgow coma scale
Max 15, Min 3
Coma of 8
Eye opening is an indication of arousal
Absent eye opening distinguishes - coma/brainstem death from PVS and MCS
Divided into eye opening, best motor response to verbal command, best verbal response
What is a vegetative state
Absent awareness (& hence consciousness)
Preserved arousal (preserved sleep/wake cycle)
No voluntary response to environment
Variably preserved reflex responses to environment
Cause: widespread damage to cerebral cortex (esp anoxia, head injury) – Neocotical Brain death
Persistent Vegetative State >4 weeks
Permanent Vegetative State
What is a minimally conscious state?
Like Vegetative State, but with at least one of 11 items consistent movement to command reproducible movement to command object recognition object localization reaching visual pursuit fixation automatic motor response object manipulation localization to noxious stimulation intelligible but non-functional verbalization Emergence from MCS signaled by at least one of 2 items: functional communication object use.
What is locked in syndrome?
Conscious (aroused & aware) Unable to respond (de-efferented) Most cases are partially locked in: preserved vertical eye movements reserved eye opening
What are the causes of locked in syndrome?
Ventral Pontine Damage
Severe Guillain Barre Syndrome
What is brain stem death?
Irreversible cessation of brainstem function Such that consciousness could never be regained Absent Reflexes Pupils Ice Calorics Corneals Pain Gag Cough Apnoea 5 min test after pre-oxygenation and allowing CO2 to reach 6Kpa No arousal
What are the legal requirements of brain stem death?
Presence of an irreversible cause (eg anoxia, structural damage)
Absence of reversible cause; drugs, hypothermia, alcohol, poisons, metabolic (pupils react) or electrolyte disturbances
Irreversible cessation of function of
Brainstem (brainstem death) – confirmed by 2 doctors
Cerebral cortex (neocortical death)
Body
Must be repeated after 24 hours
Ongoing life support?
Organ donation
