PDF - Coma / Death

Question 1

Definition coma?

Answer 1

Sleep-like, unarousable, unresponsive state

- Only stem reflexes are testable, since cortical function is absent

Question 2

What is persistent vegetative state?

Answer 2

1. Eyes periodically open or move
2. Sleep / wake cycles occur
3. Pain responsiveness may return
4. Meaningful interaction remains absent since severe cortical impairment persists

Question 3

Can unilateral brain lesion cause coma?

Answer 3

Not unless it adversely affects opposite hemisphere via edema or herniation

Question 4

How can brain stem lesion cause coma?

Answer 4

If reticular formation which is responsible for wake, sleep cycles is damaged

Question 5

Command or pain withdrawal seen in coma?

Answer 5

No

Question 6

What are decorticate and decerebrate posturing?

Answer 6

Decorticate: flexion of upper limbs w/ extension of lower
- Associated w/ lesion at level of cerebral cortex
Decerebrate: extension of upper and lower limbs
- Associated with a lesion at midbrain (red nucleus)

Question 7

What is Cheyne-Stokes respiration?

Answer 7

Alternating tachypnea and apnea (crescendo-decrescendo respiration)
- Patient observed to take progressively deeper, often faster, breaths, followed by slower shallower breathing leading to apnea

Question 8

Causes Cheyne-Stokes respiration?

Answer 8

1. Bilateral cortical lesions

2. Toxic metabolic encephalopathy

Question 9

Lesion causing neurogenic hyperventilation?

Answer 9

1. Low midbrain

2. Upper pons

Question 10

Cause ataxic respiration?

Answer 10

Lesion or edema in the medulla
- Ominous sign, signaling respiratory arrest and
emergent need to intubate and ventilate

Question 11

Lesion causing large blow pupils?

Answer 11

1. Tectal (dorsal) midbrain lesion
   - Selectively involves PS fibers, causing large, fixed pupils (unopposed sympathetic fibers)
2. Compression of ipsilateral CN III from swollen temporal lobe (uncal herniation)

Question 12

Lesion causing small pinpoint pupils?

Answer 12

1. Pontine
2. Narcotics
3. Glaucoma meds

Question 13

What does asymmetric eye reflexes point to?

Answer 13

Structural lesion is more likely cause of coma than a toxic metabolic

Question 14

How to reduce ICP in comatose?

Answer 14

1. Hyperventilation
   - Intracranial blood volume is reduced since hypocarbia causes arterial vasoconstriction
2. Osmotic diuretics like mannitol
3. Dexamethasone
   - Can counteract edema produced by a cerebral tumor, abscess or encephalitis

Question 15

Can brain death be diagnosed with heart still beating?

Answer 15

Yes

Question 16

What is needed to diagnose brain death?

Answer 16

1. Cause must be know

2. Must be severe enough to account for state

Question 17

What should not be seen in diagnosing brain death?

Answer 17

1. Decorticate or decerebrate posturing
2. Seizures
3. Swallowing
4. Yawning
5. Vocalizations

Question 18

Muscle reflexes still seen in brain death?

Answer 18

Those mediated by spinal cord:

1. Muscle stretch reflexes
2. Babinski sign

Question 19

What must be absent in brain death?

Answer 19

1. All cranial nerve
2. All brain stem reflexes
3. Any spontaneous respirations