Coma, persistent vegetative state and brain death Flashcards
what is a coma
A state of unrousable psychological unresponsiveness
subjects lie with eyes closed and show no psychologically understandable response to external stimulus or inner need
what 2 components does consciousness depend on
AROUSAL
need an intact ascending reticular activating system
- acts as the alerting or awakening element of consciousness
ENVIRONMENTAL AWARENESS
need a functioning cerebral cortex of both hemispheres
- determines the content of that consciousness
what can cause your GCS to drop
Toxic/metabolic states
- Hypoxia, hypercapnia, sepsis, hypotension
- Drug intoxication/renal or liver failure
- Hypoglycaemia, ketoacidosis
Seizures
Damage to reticular activating system
Causes of raised intracranial pressure
- tumour, stroke, EDH, SDH, SAH, hydrocephalus
what is a persistent vegetative state
the brain stem recovers to a considerable extent but there is no evidence of recovery of cortical function
arousal and wakefulness but no awareness or purposeful behaviour of any kind
what is locked in syndrome
total paralysis below the level of the third nerve nuclei
although able to open, elevate and depress the eyes, has no horizontal eye movements and no other voluntary eye movement
cognitive function unaffected, can still hear, see, have sleep-wake cycles
what does the diagnosis of locked in syndrome depend on
recognising that the patient can open their eyes voluntarily and signal numerically by eye closure
what can cause depressed respiration
drug overdose, metabolic disturbance
what can cause increased respiration
hypoxia, hypercapnia, acidosis
what can cause fluctuating respiration
brainstem lesion
what are the stabilising steps in presenting a coma
ABC
blood samples - glucose, biochemistry, haematology, blood gas, toxicology
establish BP, pulse, temp, IV access
stabilise neck
examine for meningitis
what should be continuously monitored in a coma
Temperature Heart rate, Blood Pressure, CVS Respiration Skin, breath Abdomen Meningism Fundal examination
what from the history can give you an idea about what caused the coma
? Predictable progression of underlying illness
? Unpredictable event in patient with previously known disease
? Totally unexpected event
- Head injury, sudden collapse, limb twitching, previous history of drug or alcohol abuse
what comprises the neurological assessment of coma
GCS
brainstem function
motor function +reflexes
what are the three aspect of the GCS
eye opening
best verbal response
best motor response
how is eye opening scored in GCS
Spontaneous - 4
To speech - 3
To pain - 2
None - 1
how is the best verbal response scored in GCS
Orientated - 5 Confused - 4 Inappropriate words - 3 Incomprehensible sounds - 2 None - 1
how is the best motor response scored in GCS
Obeying Commands - 6 Localising to pain - 5 Withdrawing from pain - 4 Flexing to pain - 3 Extending to pain - 2 None - 1
when does the GCS indicate a coma
<8
Eye opening - 2 or less
Verbal response - 2 or less
Motor response - 4 or less
*less than 8 = intubate
what motor functions looked for in coma
motor response
muscle tone
tendon reflex
seizures
what can cause coma without focal or lateralising signs and without meningism*
*neck stiffness, photophobia, headache
Anoxic/ ischaemic conditions Metabolic disturbances Intoxications Systemic infections Hyperthermia/ Hypothermia Epilepsy
what investigations should be done for coma -f/l signs and
-meningism
toxicology - alcohol blood sugar electrolytes assess hepatic/renal functions acid/base assessment BP ?CO poisoning
what can cause coma without focal or lateralising signs with with meningism
subarachnoid haemorrhage
meningitis
encephalitis
what investigations should be done for coma -f/l signs and +meningism
CT head scan
LP
- appearance CSF
- cell count
- glucose
- capsular antigen tests
what can cause coma with focal brainstem or lateralising cerebral signs
Cerebral tumour
Cerebral haemorrhage
Cerebral infarction
Cerebral abscess
