37 Coma

Question 1

Abulia:

Answer 1

eyes open but demonstrates no spontaneous interaction with the environment

may answer questions with vigorous stimulation

Question 2

Causes of abulia?

Answer 2

severe bifrontal lobe damage (lobotomy at its worst)

Question 3

Akinetic mutism:

Answer 3

no evidence of mental activity can be elicited with vigorous stimulation; “vegetative”

Question 4

Sleep promoting area?

Destruction causes…

Answer 4

ventrolateral preoptic nucleus

insomnia

Question 5

Location of arousal center?

Answer 5

midbrain (RAS)

Question 6

MC site of lesion generating coma?

Answer 6

paramedian tegmental area just ventral to the aqueduct of Sylvius from the midbrain to the rostral pons

Question 7

Lesions confined to _____ can cause coma in the absence of midbrain and thalamic injury

Answer 7

upper pons

Question 8

Location of RAS?

Answer 8

intralaminar nuclei of thalamus, tegmentum of midbrain, tegmentum of upper 1/3 pons

Question 9

Role of monoaminergic systems?

Answer 9

improve the signal to noise ratio for messages from the thalamus (= prevent any misperception of incoming sensory stimuli)

Question 10

Function of VLPO?

Answer 10

inhibit the many centers that promote wakefulness in the ascending arousal system

Question 11

Ascending Arousal System receives feedback from:

Answer 11

thalamus, the limbic system, the frontal and association cortex

Question 12

Why is it important for Ascending Arousal System to receive feedback?
Loss causes:

Answer 12

pathways mediate emotional memories, permit concentrated attention to 1 sensory modality when necessary

Loss = apathy and indifference to sensory stimuli

Question 13

Transtentorial herniation of the medial temporal lobe or the uncus of the temporal lobe causes:

Answer 13

1. CN3 entrapment, likely starting with pupillary contr nerves
2. PCA entrapment (causing ipsalat ischemia and stroke in the occipital lobe)

(then, pressure on the midbrain and diencephalon produce ischemia and cause increasing lethargy, stupor and coma)

Question 14

Falcine herniation sometimes traps and compresses:

What does this cause?

Answer 14

one or both anterior cerebral arteries against the falx

ischemic stroke in the parasagittal cortex on one or both sides

Question 15

Progression of central herniation?

Answer 15

rostral to caudal

1. reticular grey in both thalami
2. hypothalamus
3. midbrain
4. Decorticate or flexor posturing (late)
5. decerebrate or extensor posturing (late)

Question 16

Effects of thalami compression in central herniation?

Answer 16

increasing lethargy due to early pressure on the reticular grey in both thalami

Question 17

Effects of hypothalamic compression in central herniation?

Answer 17

central sympathetic tracts originating in hypothalamus compromised –> small but still reactive pupils

**small due to the unopposed cholinergic activity mediated by the Edinger-Westphal nucle

Question 18

Effects of midbrain compression in central herniation?

Answer 18

Edinger-Westphal nuclei fail = Constrictive pupillary tone is lost + pupils become fixed in mid-position

Question 19

Early warning of central herniation?

Answer 19

Cheyne-Stokes respirations (apneic spells interspersed with hyperventilation periods)

Question 20

Intrinsic brainstem lesions causing infratentorial compression?

Answer 20

top of basilar artery ischemic stroke

pontine hemorrhage

Question 21

Extrinsic brainstem lesions causing infratentorial compression?

Answer 21

cerebellar hemorrhage
cerebellar infarction
cerebellar brain tumor

Question 22

1’ brainstem lesions cause:

Answer 22

1. segmental CN deficits
2. asc spinothalamic tract dysf
3. desc corticospinal tract dysf
4. early cerebellar signs

Question 23

Pontine hemorrhage: Clinical syndrome?

Answer 23

• abrupt coma
• pinpt pupils
• decerebrate rigidity or flaccid quadriplegia
• horiz gaze paresis
• ocular

Question 24

How does one recognize metabolic encephalopathy at the bedside?

Answer 24

neurological deficits are diffuse and global

Question 25

CT in metabolic encephalopathy?

Answer 25

nml

Question 26

Symptoms in metabolic encephalopathy?

Answer 26

- pupils stay reactive to light - asterixes - multifocal myoclonus - tremor

Question 27

Account for about 90% of delirium in the elderly:

Answer 27

dehydration, drug intoxication and infection

Question 28

In non-traumatic coma, absence of ____ carries a poor prognosis.

Answer 28

pupillary light reflex at 3 days

Question 29

In hypoxic coma, absence of ____ carries a poor prognosis.

Answer 29

purposeful motor movement in 3 days