Coma, persistent vegetative state & brain death Flashcards
Define coma
A state of unarousable psychological unresponsiveness
Consciousness depends on what 2 things
1) An intact ascending reticular activating system to act as the alerting or awakening element of consciousness
2) A functioning cerebral cortex of both hemispheres which determines the content of that consciousness (i.e. being aware of environment)
Define a persistent vegetative state (2)
A state in which the brain stem recovers to a considerable extent but there is no evidence of recovery of cortical function
There is arousal and wakefulness but the patient does not regain awareness or purposeful behaviour of any kind
Causes of a decreased GCS (9)
Head trauma
Toxic/metabolic states - e.g. hypoxia, hypercapnia, hypoglycaemia, drug/alcohol intoxication
Seizures
Damage to reticular activating system
Stroke
Subarachnoid haemorrhage
Questions to ask yourself when taking a history of a coma patient (3)
o Is it a PREDICTABLE progression of their underlying illness
o Or UNPREDICTABLE event of previously known disease
o Or TOTALLY UNEXPECTED – e.g. head trauma, sudden collapse, drug/alcohol abuse
Neurological assessment of a coma involves what 3 things
GCS score, if ≤8 = coma
Brainstem function
Motor function + reflexes
Brainstem function can be tested with what 6 things
Pupillary reflex Corneal reflex Spontaneous eye movements Oculocephalic reflex (doll's eye) Oculovestibular reflex Resp pattern
What is the oculocephalic reflex (doll’s eye)
If brainstem intact, eyes would stay fixed on an object as you turn your head but if brainstem not intact, eyes move with the head and can’t stay fixed on an object
What is the oculovestibular reflex
If normal cortical & brainstem response – COWS (cold opposite: quick nystagmus (cortical response) away from stimulus side, then slow nystagmus back (brainstem response))
If abnormal cortex but intact brainstem – eyes move towards stimulus side
Name the 3 types of coma
Coma WITHOUT focal or lateralising signs (unilateral signs) + WITHOUT meningism
Coma WITHOUT focal or lateralising signs (unilateral signs) + WITH meningism
Coma WITH focal or lateralising signs (unilateral signs) +/- meningism
Causes of Coma WITHOUT focal or lateralising signs (unilateral signs) + WITHOUT meningism (4)
Drug/alcohol intoxication
Metabolic disturbances - e.g. hypoglycaemia, hypothermia
Systemic infections
Epileptic seizures
Causes of Coma WITHOUT focal or lateralising signs (unilateral signs) + WITH meningism (3)
Subarachnoid haemorrhage
Meningitis
Encephalitis
Causes of Coma WITH focal or lateralising signs (unilateral signs) +/- meningism (4)
Focal cerebral lesion: Cerebral tumour Cerebral haemorrhage Cerebral infarct Cerebral abscess
Investigations of coma (7)
ABGs U&Es Blood glucose LFTs - if liver failure suspected Blood culture - only if fever or hypothermia
CT
LP + CSF analysis
EEG
Factors affecting prognosis of coma patients (5)
Age Cause of coma Depth of coma Duration of coma If brainstem reflexes are intact
