The Unconscious Patient Flashcards
What is consciousness?
Awareness of self and surroundings, combination of awareness and wakefulness
What is awareness?
Ability to have and having experience of any kind
What is wakefulness?
is a state in which the eyes are open and there is a degree of motor arousal, contrasts with sleep – a state of eye closure and motor quiescence
What is consciousness regulated by?
Regulated by ascending reticular activating system – comes up through brainstem, triangulates thalamus
Intralaminar nuclei of the thalamus maintains arousal
ARAS contains cholingeric neurons
Monosminergic neurons project from upper brainstem to thalamus, basal forebrain and cortex
What does stimulation of the posterior hypothalamus result in ?
arousal
What is abulia and what can cause it?
Abulia – lack of motivation due to anterior cingulate lesions (distinct from unconsciousness)
What possible conditions cause LoC?
Problem in brainstem stopping ARAS
Problem in thalamus – at junctions of ARAS
Bilateral hemispheres – must be bilateral
Was is the definition of coma?
Unrousable Unresponsive >6 hours Cannot be wakened Lacks normal sleep-wake cycle No voluntary actions (can have reflex actions e.g. withdrawal from pain
What is the definition of vegatative state?
Can be diagnosed after 4 weeks – continuing vegetative state
Considered permanent if >1 year following TBI (given longer time as increased prospect of improvement following TBI), >6 months in other mechanisms
What is the definition of minimally conscious state?
Severely altered consciousness
Minimal evidence of self and environmental awareness at best
Inconsistent but reproducible responses to surroundings e.g. everytime a relative comes in the patient cries
Follow simple commands – areas of cortex preserved
Emotional responses to emotional stimuli e.g. crying, smiling, laughing
Reaching for objects with intent
Eye movement pursuit
Can be diagnosed after 4 weeks – ‘continuing’
Permanent if >5 years
Permanent if >3-4 years if diffuse injury seen on scans etc. and no improvement seen
What are the preconditions for diagnosis of VS or MCS?
Need to know cause of condition
Reversible causes excluded e.g. medications, metabolic disorders, structural causes such as haemorrhage/haematoma that can be treated.
Also Guillain-Barre Syndrome, a demyelination syndrome and if it affects the brainstem white matter can cause unconsciousness
Careful assessment
What are possible causes of prolongued disorders of consciousness?
Trauma – direct impact or deceleration injury
Vascular – ICH, SAH, CVA
Drugs/alcohol – generally reversible
Metabolic - severe hypoglycaemia that is unknown until on brink of coma – generally bad outcome as every neuron effected
Hypoxic – Cardiac arrest, shock
Inflammation/infection – encephalitis, vascuclitis §
What are some chronic states of altered conciousness and coma mimics?
Dementia
Hypersomnia
Akinetic mutism
Silent, alert, immobile, sleep wake cycles, no external evidence of mental activity and no spontaneous motor activity.
Apallic syndrome
Absent neocortical and preserved brainstem activity
Locked in syndrome
What is locked in syndrome? What can cause it?
Conscious and aware of self and the environment
No voluntary movement
High brainstem pathology with retention of blinking or vertical eye movement – sometimes not, this makes it almost impossible to diagnose
Central pontine myelinolysis most likely cause
Rapid over correction of hyponatraemia is also a cause– normally at hospital as patient would not think to correct hyponatraemia
What must be taken to assess PDOC?
collateral history
General examination
Neurological examination
