Consciousness (Lecture 19)

Question 1

4 major components of brainstem

Answer 1

cranial nerve nuclei & related structures
long tracts
cerebellar circuitry
reticular formation and related structures

Question 2

long tracts

Answer 2

dorsal column medial lemniscal pathway
lateral corticospinal tract
spinothalamic

Question 3

clinical consequences of damage to CN nuclei and related structures

Answer 3

cranial nerve abnormalities

Question 4

clinical consequences of damage to long tracts

Answer 4

hemiparesis and/or hemianesthesia

Question 5

clinical consequences of damage to cerebellar circuitry

Answer 5

ataxia

Question 6

clinical consequences of damage to reticular formation and related structures

Answer 6

impaired level of consciousness

impairment in autonomic functions (BP, HR)

Question 7

what is the reticular formation

Answer 7

core of cell bodies loosely grouped into nuclei that run throughout the entire length of the brainstem tegmentum (above the basis)

Question 8

function of reticular formation

Answer 8

rostral 1/2: maintenance of alert, consciousl state in the cerebrum
caudal 1/2: autonomic reflexes (HR, BP, respiration, digestion), motor (origin of reticulospinal tract), reflexes involving the head (coughing, sneezing, swallowing, sucking, etc)

Question 9

where is rostral 1/2 of reticular formation found

Answer 9

midbrain and rostral pons

Question 10

where caudal 1/2 of reticular formation found

Answer 10

caudal pons and medulla; continuous with grey matter of spinal cord

Question 11

purpose of reticular activating system

Answer 11

sends info from pontomesencephalic reticular formation to the thalamus and finally the cerebral cortex

Question 12

requirements of consciousness

Answer 12

alertness (RAS)
attention (RAS, limbic system, frontal & parietal lobes)
awareness of surroundings (primary sensory cortices and sensory association cortex)

Question 13

Coma

Answer 13

unarousable unresponsiveness

• pt lies with eyes closed
• brainstem reflexes still present
• no sleep wake cycles

Question 14

brainstem reflexes

Answer 14

blink to threat
pupillary light response
oculocephalic reflex
corneal reflex
gag reflex

Question 15

how to test blink to threat (CN II, VII)

Answer 15

hold eyes open and come toward pt with hand. both eyes should blink

Question 16

how to test pupillary light response (CN II, III)

Answer 16

shine light in eye, pupil constricts

Question 17

how to test oculocephalic reflex (CN VIII, III, VI)

Answer 17

hold eyes open, turn head to left, eyes should move right

Question 18

how to test corneal reflex (CN V, VII)

Answer 18

touch cornea with wisp of cotton, both eyes should blink

Question 19

how to test gag reflex (CN IX, X)

Answer 19

touch back of throat with tongue depressor, pt should gag

Question 20

continuum between consciousness and coma

Answer 20

awake and alert
drowsy
stuporous
comatose
brain death

Question 21

glasgow coma scale

Answer 21

helps determine progonsis in TBI, measures level of consciousness

Question 22

highest possible score on glasgow coma scale

Answer 22

15

Question 23

worst possible score on glasgow coma scale

Answer 23

3

Question 24

what score on the glasgow coma scale indicates a good prognosis

Answer 24

8 or higher

Question 25

bilateral damage to these structures leads to a permanent comatose state

Answer 25

cerebral hemispheres medial aspect of thalami bilaterally reticular formation of the pons and midbrain

Question 26

how to perform neurologic exam with someone with decreased level of consciousness

Answer 26

cranial nerve reflexes observe for motor activity reflexes response to pain (sternal rub, nail bed pressure)

Question 27

decorticate posture

Answer 27

LE extended, UE flexed | rubrospinal tract

Question 28

decerebrate posture

Answer 28

UE and LE ext | reticulospinal tract/vestibulospinal tract

Question 29

most common general cause of decreased level of consciousness

Answer 29

bilateral cerebral hemisphere dysfunction (due to trauma or toxic/metabolic causes)

Question 30

what can cause bilateral cerebral hemisphere dysfunction

Answer 30

``` medications illicit drugs liver failure kidney failure hypoxia trauma ```

Question 31

why do pts with a decreased LOC often require an imaging study of the brain

Answer 31

determine if there is anything that can be fixed

Question 32

``` Which of the following are present in brain death? purposeful response to stimuli sleep-wake cycles cranial nerve reflexes cortical electrical activity cortical blood flow ```

Answer 32

``` purposeful response to stimuli- no sleep-wake cycles- no cranial nerve reflexes- no cortical electrical activity- no cortical blood flow- no ```

Question 33

``` Which of the following are present in coma purposeful response to stimuli sleep-wake cycles cranial nerve reflexes cortical electrical activity cortical blood flow ```

Answer 33

``` purposeful response to stimuli- no sleep-wake cycles- no cranial nerve reflexes- yes cortical electrical activity-abnormal cortical blood flow-yes ```

Question 34

``` Which of the following are present in persistent vegetative state? purposeful response to stimuli sleep-wake cycles cranial nerve reflexes cortical electrical activity cortical blood flow ```

Answer 34

``` purposeful response to stimuli- no sleep-wake cycles- yes cranial nerve reflexes- yes cortical electrical activity- yes cortical blood flow- yes ```

Question 35

``` Which of the following are present in minimally conscious state purposeful response to stimuli sleep-wake cycles cranial nerve reflexes cortical electrical activity cortical blood flow ```

Answer 35

``` purposeful response to stimuli- inconsistent sleep-wake cycles- yes cranial nerve reflexes- some cortical electrical activity- yes cortical blood flow- yes ```

Question 36

criteria for brain death

Answer 36

``` no purposeful response to painful stimuli no CN reflexed no spontaneous respirations no reversible cause for coma EEG or angiogram 2 separate exams required ```

Question 37

difference between persistent vegetative state and minimally conscious state

Answer 37

they are the same except minimally conscious state my intermittently and inconsistently perform any of the following: - visual tracking - follow simple commands - signal yes/no - intelligible verbalizations - restricted purposeful behavior

Question 38

what causes locked-in syndrome

Answer 38

bilateral damage to basis of pons (typically bilateral infarct)

Question 39

symptoms of brain ischemia

Answer 39

- face motor/sensory loss on one side and body motor/sensory loss on the other side - eye movement abnormalities - pupillary abnormalities - nystagmus

Question 40

lateral medullary syndrome caused by

Answer 40

PICA thrombosis