Coma W3 Flashcards
consciousness origination in brain?
reticular formation (arousal)
cerebral hemispheres and diencephalon (perception of content around you)
coma pathophysiology?
impaired function of
both cerebral hemispheres
reticular activating system in brainstem or diencephalon
or both of above
what factors cause coma?
structural lesions (20%)
metabolic (35%)
drugs and toxins (25%)
CNS infections
stroke
other
what causes diffuse (widespread) hemispheric problems
trauma
ischaemia
hypoglycaemia/other met disorders
infection
drugs
causes of bilateral changes in brain stem
haemorrhage
compression eg mass lesions
drugs
structural causes of coma?
pressure on reticular acting system of brain stem which may lead to focal neurological signs eg hemiparesis, papilloedema or 3rd nerve palsy
especially common with posterior fossa masses
what is hemiparesis?
weakness down one side of body
what is papilloedema
swelling of optic disks
what is uncal herniation
mass (eg brain tumor) pushes through uncus, medial temporal lobe compressed, problems with 3rd nerve and brain stem
name of innermost part of temporal lobe (hook-shaped)
uncus
what is coning?
progressive brain stem compression
tonsil herniation? what does this cause/lead to
herniation through foramen magnum
causes loss of all brainstem reflexes leading to death
metabolic cause of coma?
hypoxia
hypercapnia
deranged electrolytes (renal failure)
endocrine problems
hepatic encephalopathy (liver failure)
uraemia
hypothermia
drugs and toxins causes of coma?
overdose
opiates (pinpoint pupils)
sedatives
alcohol
CO
poisons
CNS infections causing coma?
meningitis, encephalitis
other causes of stroke?
trauma
seizures
management of coma?
resuscitation
history (circumstances - where and when)
general examination
neurological examination
investigations
supportive and specific treatments
general examination for coma?
temperature? (fever, hypothermia)
meningism (neck stiffness, kernig’s sign)
trauma (blood, battles sign, racoon eyes etc)
skin (cyanosis, jaundice etc)
breath - alcohol?
BP
neurological examination for coma aims to determine what?
level of consciousness
brainstem function
lateralisation of pathology
neurological examination for coma?
pupil size and activity
eye movements (baseline position?)
corneal reflex intact? (indicates cranial nerves intact)
respond to painful stimulus with motor response?
tone and reflexes in arms and legs
coma with no focal signs and no meningism indicates what cause?
metabolic eg:
drugs/toxins
hypoxic-ischaemic
seizure
coma with focal signs and no meningism indicates what cause?
mass lesion
haemorrhage
infarction (stroke)
coma with meningism and no focal signs indicates what cause?
meningitis
meningo-encephalitis
SAH (sub-arachnoid hemorrhage)
brainstem functions
respiratory rate and rhythm
pupillary reaction
corneal reflex
spontaneous eye movements
reflex eye movements
gag/cough reflex
examination of brainstem functioning?
examination of pupils
papilloedema
sub-hyloid haemorrhage
pupil size + reactions
resuscitation and investigation for coma?
maintain airway
give dextrose if hypoglycaemic
consider thiamine + naloxone
treat seizures
antibiotics if there’s suggestion of infection
what does thiamine reverse the effects of
alcohol excess
what does naloxone reverse the effects of
opiate excess
priority blood tests for coma?
electrolytes
arterial blood gas
priority tests for coma?
urgent CT head
lumbar puncture
