Coma and End of Life

Question 1

Coma

Answer 1

Coma is defined as a sleep-like, unarousable, unresponsive state.

Question 2

Persistent Vegetative State

Answer 2

The eyes periodically open or move, sleep and wake cycles occur, and pain responsiveness may return, but meaningful interaction remains absent since severe cortical impairment persists.

Question 3

What are some possible causes of coma?

Answer 3

• Hypoxia
• Cerebral Hypotension
• Hypoglycemia
• Drug intoxication/overdose

Question 4

Can a solitary unilateral cerebral lesion cause coma?

Answer 4

No. Unless it affects the opposite hemisphere via brain edema or herniation.

Question 5

How can a brain stem lesion cause coma?

Answer 5

Coma may be produced by a brain stem lesion if it disrupts the reticular formation.

Question 6

What are asymmetrical neurological signs suggestive of?

Answer 6

Structural Lesion - ischemic infarction, hemorrhage or tumor

Question 7

What are symmetrical neurological signs suggestive of?

Answer 7

Toxi-metabolic Process - anoxia

Question 8

Decorticate Posturing

Answer 8

Decorticate posturing is flexion of the upper limbs with extension of the lower limbs associated with a lesion at the level of the cerebral cortex or hemisphere.

Question 9

Decerebrate Posturing

Answer 9

Decerebrate posturing is extension of the upper and lower limbs, associated with a lesion at the level of the midbrain (red nucleus).

Question 10

What is Cheyne-Stokes respiration indicative of?

Answer 10

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

***Elderly patients can have this pattern of breathing as they sleep

Question 11

Central Neurogenic Hyperventilation

Answer 11

Lesion in the low midbrain to upper pons

Question 12

Ataxic Respiration Pattern

Answer 12

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

Question 13

What happens to the pupillary light reflex in patients with coma from metabolic causes?

Answer 13

Often in coma from metabolic causes the pupillary light reflex is preserved

Question 14

What can large, blown and fixed pupils be indicative of?

Answer 14

Uncal Herniation

Question 15

What happens to the pupils with a pontine lesion?

Answer 15

A pontine lesion selectively involves the sympathetic fibers, causing small, pinpoint pupils

Question 16

Oculocephalic Reflex “doll’s eyes”

Answer 16

The eyes should normally move in the direction opposite to the lateral turn of the head.

Question 17

Oculovestibular Reflex “cold caloric”

Answer 17

Eyes normally move slowly toward the cold (irrigated) ear

Question 18

What should be immediately ruled out in an emergency coma?

Answer 18

Hypoglycemia

Question 19

How does hyperventilation decrease ICP?

Answer 19

Intracranial blood volume is reduced since hypocarbia from hyperventilation causes arterial vasoconstriction

Question 20

Brain Death

Answer 20

Irreversible loss of function for both cerebrum and brain stem, leading to the inevitable failure of other vital organs, including the heart.

Question 21

What is the current preference for the confirmation test of brain death?

Answer 21

Current preference is absent cerebral blood flow over a 10 minute period on radioisotope brain scan