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Flashcards in Coma End of Life Deck (22)
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sleep-like unarousable nonresponse state
-only brain stem reflexes are clinically testable
-cortical function absent


persistive vegetative state

eyes periodically open or move, sleep and wake cycles occur, and pain responsiveness my return but meaningful interaction remains absent since sever cortical impairment persists


What things directly/indirectly cause affect the cerebral cortex?

2. inadequate cerebral blood flow
3. hypoglycemia
4. drug intoxication
1. systemic infection
2. metabolic disturbances
3. hepatic or renal failure


A solitary, unilateral cerebral lesion does not produce a coma unless what?

it adversely affects the opposite hemisphere via brain edema or herniation


What type of brainstem lesion can lead to a coma?

disruption of the reticular formation
-responsible for wakefulness and arousal
-projects from tegmental brainstem to thalamus and subcortical nuclei


What do asymmetrical neurological signs suggest?

structural lesion
-ischemic infarction, hemorrhage, or tumor


What do symmetrical neurological signs suggest?

more diffuse or toxi-metabolic process
-such as anoxia


Do motor responses to command or withdrawal to pain stimuli occur in coma?

no because localizing response to a noxious stimulus requires some cortical function
-may show certain stereotyped or automatic movements spontaneously or after painful stimulus such as decorticate or decerebrate


Decorticate posturing

flexion of the upper limbs with extension of the lower limbs

-associated with lesion at the level of :
cerebral cortex or hemisphere


Decerebrate posturing

extension of the upper and lower limbs

-associated with lesion at the level of :
midbrain (red nucleus)


cheyne-stokes respiration

alternating tachypnea and apnea (crescendo-decrescendo respiration)

-bilateral cortical involvement due to metabolic encephalopathy
-such as from: renal failure, unilateral lesion with severe brain edema, or from bilateral structural lesions in cerebral cortex


What does central neurogenic hyperventilation result from?

lesion or edema in the low midbrain to upper pons


Ataxic respiration patttern

variable breaths at an irregular rate from lesion or edema in the medulla


What type of coma results in the pupillary light reflex being preserved despite loss of other brainstem or cranial nerve reflexes ?

metabolic causes


A tectal midbrain lesion selectively involves the parasympathetic fibers causing what?

large, fixed pupils


The presence of a larger blown fixed pupil which is unresponsive to consensual or direct light is often due to what?

compression of the ipsilateral oculomotor nerve CN3 from a swollen temporal lobe (uncal herniation)


A pontine lesion selectively involves what lading to small pinpoint pupils?

sympathetic fibers


oculocephalic reflex

dolls eyes reflex
-brainstem mediated reflex
eyes should move in the opposite direction of the turned head

(if doesn't move brainstem depressed)


oculovestibular reflex

(cold caloric)
-brainstem mediated
-eyes to turn toward cold ear
(if doesn't move brainstem depressed)


What does dexamethasone do?

counteract the edema produced by a cerebral tumor, abscess or encephalitis

(doesn't affect edema from ischemia infarction or hemorrhage)


Brain Death

Irreversible loss of function of both the cerebrum and brainstem


What do you need to declare brain death?

1. apparent cause should be known
2. must be sufficient to account for the irreversible coma
3. bedside neuro exam should not show any hint or suggestion of cerebral function in a comatose patient unresponsive to painful stimuli
-no decorticate or decerebrate post, seizures, swallowing yawning, or vocalizations
----except some spinal cord mediated movements may still persist (stretch reflex and babinski)
4. all cranial nerves or brainstem reflexes must be absent
5. apnea can be verified by specific testing
6. confirmation tests of brain death are not required-radioisotope brain scan-absence of cerebral blood flow

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