COMA Flashcards
What is a coma?
State of unresponsiveness, in which a patient cannot be aroused
Awareness is
Content of consciousness
Awareness occurs as a result of …
activity in cerebral cortex (supratentorial, matter) - loss of awareness seen in vegetative state
Arousal is
level of consciousness/alertness (high in normal wakefulness)
Arousal occurs as a result of
activity with specific brainstem and diencephalic structures (deep in thalamus)
In a coma, anesthesia or sleep how is awareness and arousal?
Both are zero
In a vegetative state how is arousal…(1)
how is awareness (2)
Arousal is HIGH
Awareness is LOW
In a minimally conscious state how is arousal…(1)
how is awareness (2)
- Arousal is HIGH
2. Awareness is ABOVE zero.. but low
In lesions causing coma what happens to cerebral cortex?
BILATERAL damage of both hemispheres or ascending arousal system including
1) paramedian region of upper brainstem or
2) diencephalon on both sides of the brain
In locked in syndrome what 3 things in intact
Awareness
Vertical eye movements
Vision
Where does lesion in locked in syndrome occur
BELOW level of arousal,
in the caudal pons - wipe out cortico spinal and corticobulbar tract
What are some causes of coma ?
- structural brain disease (supratentorial or infra outside dura, inside dura, blood, pus, tumor)
- destructive lesions - not extra tissue, loss of oxygen, encephalitis (supra or infra tent)
- epilepsy, diffuse intrinsic lesions in the brain
- metabolic disease - severe anoxia, low blood glucose, liver failure, acid-base imbalances
What is tonsillar herniation
swelling within cerebellum after infarct, edematous, cerebellum expands, pushes forward
1) first thing that happens is respiratory pause - presses on medullary respiratory center
how do you treat a tonsillar herniation?
suboccpital craniotomy
how do you treat a patient with an epidural hematoma?
- ABCs
REDUCE ICP - elevate the head 30 deg
- hyperventilate - pco2 25-30 (contrict arterioles in brain )
- mannitol 20% over 30ml (diuertic pull out interstitial fluid)
evacuate the bleed
What happens in right uncal herniation?
- Decreased arousal - depressed LOC
- RIGHT CN3 palsy
- cerebral peduncle involved - LEFT hemiparesis or RIGHT hemiparesis
- PCAs - cortical blindness -occipital infarct
What is the name of the condition in which the left cerebral peduncle is pressed against the left tentorial notch?
Kernohan’s notch - FALSe localizing signals
What is the key factor in determining uncal herniation (w/r to side of the lesion?)
it’s the 3rd nerve palsy will be localizing!!!!
hemiparesis cannot be trusted
What do asymmetrical occulomotor findings typically identify?
A STRUCTURAL rather than a metabolic cause of a coma (asymmetrical findings and LOC)
What does the doll’s eye maneuver tell you?
Localize the lesion to the brainstem
- If you have a RIGHT lateral pontine lesion what will the doll’s eye maneuver show? (RIGHT PPRF nucleus)
- thrust head to left, eyes dont move gaze paralysis
2. Thrust head to right , eyes move to left
If you have a left paramedian pontine lesion (now it’s left PPRF and MLF) what will the doll’s eye maneuver show?
- Thrust the head to the left, left eye stays put called 1.5 syndrome
- thrust head to the right, gaze paralysis
(can abduct eye away from side of lesion, cannot adduct eye on side of lesion)
If you have a MLF lesion - bilateral internuclear opthamlmoplegia
neither eye can adduct
but both eyes can abduct
A lesion in the pons area will result in what kind of pupils?
Pinpoint pupils, no sympathetics
A lesion in the midbrain - what happens?
EWN destroyed, fix pupils, not reactive to light
Fluctuating level of C could indicate
Metabolic reasons for coma
general exam in state of coma
look for general signs
look for racoon eyes, look for echymosis behind ears, signs of basal skull fracture
liver failure, jaundice, ascites
meningeal signs - nuchal rigidity - board coming off bed
brudinski’s lift head - patient lifts feet
look for signs of drug abuse
subtle signs of seizures (flickering eye lids)
What are the 3 brain stem reflexes to check in a comatose patient?
- pupillary light reflex
- doll’s eye reflex (occulocephalic)
- corneal, gag
What does extension posture suggest?
lesion at level of upper brainstem - midbrain - exclude neurosurgical interventions - vegetative, no operation
what does flexion posturing suggest?
lesion at diencephalon
