Unit 7 - Neuro - Spinal Cord

Question 1

most important radicular artery

Answer 1

artery of adamkiewicz

Question 2

where does the artery of adamkiewicz most commonly originate

Answer 2

T11-T12

Question 3

what does the artery of adamkiewicz supply

Answer 3

anterior cord in thoracolumbar region (along with anterior spinal artery)

Question 4

how do sensory neurons enter the CNS from periphery

Answer 4

via dorsal nerve root

Question 5

3 neuron pathway common to spinal tracts

Answer 5

• 1st order = periphery to spinal cord or brainstem
• 2nd order = spinal cord/brainstem to a subcortical structure
• 3rd order = subcortical structure to cerebral cortex

Question 6

function of dorsal column - medial lemniscal system

Answer 6

transmits mechanoreceptive sensations:
* fine touch
* proprioception
* vibration
* pressure

Question 7

fibers that make up dorsal column

Answer 7

large, myelinated, rapidly conducting

Question 8

which transmits sensory info faster - dorsal column or anterolateral system

Answer 8

dorsal

Question 9

which is capable of 2 point discrimination - medial lemniscal system (dorsal) or spinothalamic tract (anterolateral)?

Answer 9

medial lemniscal (dorsal)

Question 10

type of fibers that make up spinothalamic tract

Answer 10

smaller, myelinated, slower conducting

Question 11

most important motor pathway

Answer 11

corticospinal tract

aka pyramidal tract

Question 12

bedside exam that can assess integrity of corticospinal tract

Answer 12

babinski test

Question 13

responses to babinski test

Answer 13

• normal = downward motion of all toes
• upper motor neuron injury: upward extension of big toe, fanning of other toes
• lower motor neuron injury: no response

Question 14

where do upper motor neurons begin and end

Answer 14

begin: cerebral cortex
end: ventral horn of spinal cord

Question 15

where do lower motor neurons begin & end

Answer 15

begin: ventral horn
end: NMJ

Question 16

how do upper vs lower motor neuron injury present

Answer 16

• upper = hyperreflexia, spastic paralysis
• lower = impaired reflexes, flaccid paralysis

Question 17

why does neurogenic shock result in bradycardia & reduced inotropy

Answer 17

impaired cardioaccelerator fibers = unopposed cardiac vagal tone

Question 18

what causes decreased CO and BP in neurogenic shock

Answer 18

decreased SNS tone = vasodilation, venous pooling

Question 19

what causes hypothermia in neurogenic shock

Answer 19

impaired sympathetic pathways from hypothalamus to blood vessels impairs ability to vasoconstrict or shiver

blood flow redistributes toward periphery & allows more heat to escape

Question 20

differentiate neurogenic shock vs. hypovolemic shock

Answer 20

• neurogenic = bradycardia, hypotension, hypothermia with pink warm extremities
• hypovolemic = tachycardia, hypotension, cool clammy extremities

Question 21

use of succs in spinal cord injury

Answer 21

avoid for 24 hours after injury & shouldn’t be used for at least 6 months after (some say a year)

Question 22

when does a pt with SCI become at risk for autonomic hyperreflexia

Answer 22

after shock phase ends (1-3 weeks)

Question 23

patho of autonomic hyperreflexia

Answer 23

spinal sympathetic reflexes return below level of injury but without inhibitory influences that would normally come from above level of injury

stimulation below SCI leads to overactive sympathetic reflexes below injury

Question 24

level of injury assoc with autonomic hyperreflexia

Answer 24

85% of pts with injury above T6 will develop
very unlikely to occur below T10

higher level of injury = more intense response

Question 25

6 situations that can precipitate autonomic hyperreflexia

Answer 25

• Stimulation of the hollow organs - bladder, bowel, or uterus
• Bladder catheterization
• Surgery - especially cystoscopy or colonoscopy
• Bowel movement
• Cutaneous stimulation
• Childbirth

Question 26

classic presentation of autonomic hyperreflexia

Answer 26

HTN
bradycardia

other s/s: nasal stuffiness, HTN, malignant HTN

Question 27

what causes bradycardia in autonomic hyperreflexia

Answer 27

baroreceptor reflex activation in carotid sinus

Question 28

best anesthesia techniques for SCI pts

Answer 28

general or neuraxial

Question 29

best treatment for HTN assoc with autonomic hyperreflexia

Answer 29

• remove stimulus
• deepen anesthetic
• rapid acting vasodilator (Nipride)

Question 30

patho of ALS

Answer 30

progressive degeneration of motor neurons in corticospinal tract

upper & lower motor neurons affected

Question 31

use of NMBs in ALS

Answer 31

• sensitive to succs
• sensitive to NDNMBs