Consciousness Flashcards
Two components of consciousness
Arousal
Awareness
System required for arousal
Ascending reticular activating system
Neurones which promote sleep when active
Ventrolateral preoptic area of the hypothalamus
Model that suggests when ARAS is active, VLPO is silent and the person is awake; and when VLPO is active, ARAS is silent and the person is asleep
Flip flop model
Hypothalamic neurotransmitters which promote wakefulness
Orexins/hypocretin
Disorder where a deficiency of orexins is found
Narcolepsy
Function of ARAS in relation to the EEG
Desynchronise the EEG to suppress slow waves and potentiate gamma waves
State where someone appears to be asleep but may become alert with vigorous stimulation
Stupor
Two main types of stupor
Organic
Psychiatric - catatonia
Test used to differentiate between organic and psychiatric stupor
Caloric testing
Eye movements seen on caloric testing in organic stupor
Deviation but no following nystagmus
Eye movements seen on caloric testing in psychiatric stupor
Nystagmus following initial deviation
Process of caloric testing
Water is irrigated into the external auditory canal
Water is either cold or warm
If cold water and healthy patient there will be nystagmus to the ipsilateral ear
If warm water and healthy patient there will be nystagmus to the contralateral ear
State where someone is unable to speak or move, but alertness appears intact and sleep/wake cycles continue
Akinetic mutism
Classical clinical finding on akinetic mutism
Absence of spasticity or rigidity
Lesions and diseases causing akinetic mutism
Thalamic stroke
Bilateral cingulate damage
Final stages of CJD
State where someone has partial arousal but no awareness
Vegetative state
Clinical finding that can differentiate a vegetative state from akinetic mutism
Spasticity and rigidity of the limbs is present in a vegetative state
Differences between vegetative state and coma
Patients in a coma have no arousal; patients in a vegetative state have partial arousal
Patient in a vegetative state may - have basic reflexes, continue wake/sleep cycle, open eyes; patients in a coma will not
Patients in a vegetative state usually would not require breathing or circulation support
Pathological cause of vegetative state
Intact ARAS and thalamus with significant cortical damage
Features of locked in syndrome
Total paralysis below the level of the third cranial nerve nucleus
Ability to open eyes voluntarily
Ability to move eyes vertically voluntarily but not horizontally
