Spinal Cord Flashcards

1
Q

Blood flow to spinal cord

A

Perfused by:
1 anterior spinal a. (anterior 2/3)
2 posterior spinal a. (posterior 1/3)
6-8 radicular a.

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2
Q

Posterior spinal arteries (2)

A

Perfuses posterior 1/3 of SC (green)

Aorta –> subclavian a. –> vertebral a. –> posterior spinal a.

Aorta –> segmental a. –> posterior radicular a. –> posterior spinal a.

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3
Q

Anterior spinal artery (1)

A

Perfuses anterior 2/3 SC (blue)

Aorta –> subclavian a. –> vertebral a. –> anterior spinal a.

Aorta –> segmental a. –> anterior radicular a. –> anterior spinal a.

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4
Q

What is the most important radicular artery?

A

artery of Adamkiewicz

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5
Q

Which spinal segment does the artery of Adamkiewicz typically enter the spinal cord?

A

T11-T12

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6
Q

What area does the artery of Adamkiewicz supply?

A

anterior cord in thoracolumbar region

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7
Q

Great radicular artery

A

Artery of Adamkiewicz

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8
Q

Anterior spinal artery syndrome

A

AKA Beck’s syndrome

aortic cross clamp above artery of Adamkiewicz –> ischemia to lower portion of anterior SC

S/S:
- flaccid paralysis of LE (corticospinal tract)
- bowel & bladder dysfunction (autonomic motor fibers)
- loss of temp & pain (spinothalamic tract)
-preserved touch & proprioception (dorsal column is perfused by posterior)

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9
Q

3 spinal pathways supplied by anterior spinal artery

A
  1. corticospinal
  2. autonomic motor fibers
  3. spinothalamic
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10
Q

List 1 spinal pathway supplied by posterior spinal artery

A

dorsal column

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11
Q

spinal cord anatomy

A
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12
Q

Grey matter

A
  • contains neuronal cell bodies
  • processing center for afferent signals
  • “H” shape
  • subdivided into 10 laminae
    1-6 in dorsal grey matter (sensory)
    7-9 in ventral grey matter (motor)
    10 central canal
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13
Q

White matter

A
  • contains axons of ascending & descending tracts
  • divided into dorsal, lateral, ventral columns
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14
Q

Sensory tracts

A
  1. Dosal column: cutaneous & gracilis
  2. Tract of Lissauer
  3. Lateral spinothalamic tract
  4. Ventral spinothalamic tract
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15
Q

Motor tracts

A
  1. Lateral corticospinal tract
  2. Ventral corticospinal tract
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16
Q

Dosal column: cutaneous & gracilis

A

fine touch & proprioception

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17
Q

Dosal Column - Medial Leminiscal System

A
  • fine touch, proprioception, vibration, pressure
  • 2 point discrimination
  • large, myelinated, rapid-conducting fibers
  • SSEPs monitor integrity
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18
Q

Meissner’s corpuscles

A

2 point discriminative touch
vibration

19
Q

Merkel’s discs

A

continuous touch

20
Q

Ruffini’s endings

A

proprioception
prolonged touch & pressure

21
Q

Pacinian corpuscles

22
Q

Tract of Lissauer

A

pain & temp

23
Q

Anterolateral system- spinothalamic tracts

A
  • lateral & ventral
  • pain, temp, crude touch, tickle, itch, sexual
  • no 2 point discrimination
    -smaller, myelinated & nonmyelinated, slower conducting fibers
    1. A-delta: 1st pain, mechanoreceptors
    2. C fibers: slow pain, polymodal nociceptors
24
Q

Lateral spinothalamic tract

A

pain & temp

25
Ventral spinothalamic tract
crude touch & pressure
26
Corticospinal tract (pyramidal tract)
- motor - lateral & ventral - voluntary fine motor control to limbs & coordination of posture -MEPs monitor integrity
27
Upper motor neurons
- cell body: cerebral cortex - synapse in ventral horn of SC - pass messages from brain to SC
28
Upper motor neuron injury
- contralateral spastic paralysis - hyperreflexia - positive Babinski ex: cerebral palsy, ALS
29
Lower motor neuron
- cell bodies: ventral horn of SC - synapse in NMJ of muscle - send message from SC to muscles
30
lower motor neuron injury
- ipsilateral flaccid paralysis - impaired reflexes - absent Babinski
31
Lateral corticospinal tract
limb motor
32
Ventral corticospinal tract
posture motor
33
What bedside exam assesses the integrity of the corticospinal tract?
Babinski test
34
Babinksi test
Assesses integrity of corticospinal tract -normal = downward motion of toes - upper motor neuron injury = upward ext of big toe w/ fanning of other toes - lower motor neuron injury = no response
35
Acute SCI
- causes: fall, MVC, assault, sports injury - C7 injury most common - flaccid paralysis & loss of sensation below level of injury - loss of bowel, bladder fx - spinal reflexes return after acute phase --> spasticity - neurogenic shock
36
Neurogenic shock
- sympathectomy below level of injury - Triad: 1. hypotension 2. bradycardia 3. hypothermia (impaired hypothalamus) - impaired cardioaccelerator fibers (T1-4) > unopposed cardiac vagal tone, bradycardia, reduced inotropy - decreased SNS tone --> vasodilation --> venous pooling --> decreased CO, BP - impaired cutaneous vasoconstriction --> heat loss
37
How can you differentiate neurogenic shock from hypovolemic shock?
- Neurogenic shock = bradycardia, hypotension, hypothermia w/ pink warm extremities - Hypovolemic shock = tachycardia, hypotension, cool clammy extremities
38
Discuss the use of sux in a patient w/ SCI
-"safe" within 24 hours - Avoid 24 hours after injury & at least 6 months thereafter
39
When is a patient w/ SCI at risk for autonomic hyperreflexia?
1-3 weeks after spinal shock phase
40
Autonomic hyperreflexia (AH)
- involuntary reaction to external stimuli in pt w/ SCI - increased SNS response below SCI - injuries above T6 - stimulation below SCI --> vasoconstriction BELOW injury & vasodilation ABOVE injury - Classic presentation: HTN & bradycardia
41
AH triggers
- bladder, bowel, uterus stimulation - catheter - surgery esp. cysto or colonoscopy - BM - cutaneous stimulation - childbirth
42
AH MGMT
- stimulation below level of SCI can trigger event - GA or spinal - Tx HTN: ~ remove stimuli ~ deepen anesthetic ~ rapid-acting vasodilator (Na+ nitroprusside) - Tx bradycardia w/ atropine or glyco - Sux contraindicated w/ chronic SCI - close postop monitoring
43
Amyotrophic Lateral Sclerosis (ALS)
- progressive degenerative of motor neurons in corticospinal tract - replaced by astrocytic gliosis - S/S 1. upper motor neurons ~ spasticity, hyperreflexia, loss of coordination 2. lower motor neurons ~ muscle wknss, fasciculation, atrophy 3. begins in hands spreads to rest of body 4. ocular muscles not affected 5. autonomic dysfunction ~ orthostatic hypotension, resting tachycardia 6. sensation intact - Riluzole (NMDA ant) reduces mortality - Resp failure most common cause of death
44
ALS MGMT
- NO SUX --> lethal hyperkalemia - increased sensitivity to NDNMB - bulbar muscle dysfx --> aspiration risk - chest wknss --> reduced VC - consider postop mechanical ventilation