Coma End of Life

Question 1

coma

Answer 1

sleep-like unarousable nonresponse state

• only brain stem reflexes are clinically testable
• cortical function absent

Question 2

persistive vegetative state

Answer 2

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

Question 3

What things directly/indirectly cause affect the cerebral cortex?

Answer 3

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

Question 4

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

Answer 4

it adversely affects the opposite hemisphere via brain edema or herniation

Question 5

What type of brainstem lesion can lead to a coma?

Answer 5

disruption of the reticular formation

• responsible for wakefulness and arousal
• projects from tegmental brainstem to thalamus and subcortical nuclei

Question 6

What do asymmetrical neurological signs suggest?

Answer 6

structural lesion

-ischemic infarction, hemorrhage, or tumor

Question 7

What do symmetrical neurological signs suggest?

Answer 7

more diffuse or toxi-metabolic process

-such as anoxia

Question 8

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

Answer 8

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

Question 9

Decorticate posturing

Answer 9

flexion of the upper limbs with extension of the lower limbs

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

Question 10

Decerebrate posturing

Answer 10

extension of the upper and lower limbs

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

Question 11

cheyne-stokes respiration

Answer 11

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

Question 12

What does central neurogenic hyperventilation result from?

Answer 12

lesion or edema in the low midbrain to upper pons

Question 13

Ataxic respiration patttern

Answer 13

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

Question 14

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

Answer 14

metabolic causes

Question 15

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

Answer 15

large, fixed pupils

Question 16

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

Answer 16

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

Question 17

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

Answer 17

sympathetic fibers

Question 18

oculocephalic reflex

Answer 18

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

(if doesn’t move brainstem depressed)

Question 19

oculovestibular reflex

Answer 19

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

Question 20

What does dexamethasone do?

Answer 20

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

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

Question 21

Brain Death

Answer 21

Irreversible loss of function of both the cerebrum and brainstem

Question 22

What do you need to declare brain death?

Answer 22

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