Apex- Spinal Cord Flashcards
The artery of Adamkiwicz (select 2):
- More commonly arises from the left side
- provides collateral circulation to the posterior spinal cord
- usually arises between T4-T8
- occlusion can cause flaccid paralysis
- More commonly arises from the left side
- occlusion can cause flaccid paralysis
(arises between T8-T12 in 75% of population)
(supplies the anterior spinal artery which serves the anterior [not posterior] two-thirds of the spinal cord
Becks syndrome is AKA:
Anterior spinal artery syndrome
The spinal cord circulation consists of what 3 types of arteries and what do they each supply?
- 2 Posterior spinal arteries - supply posterior 1/3 of SC
- 1 Anterior spinal artery
- perfuses anterior 2/3 of SC - Radicular arteries (6-8) - supply the spinal arteries in the thoracolumbar region of the spinal cord
What supply the anterior and posterior spinal arteries in the cervical region of the spinal cord?
-what about below this?
Cervical = vertebral arteries
Below = radicular and lumbar arteries
What does the artery of Adamkiewicz perfuse?
The anterior spinal cord in the thoracolumbar region
The artery of Adamkiewicz usually originates on which side (left/right) and at which level?
Left side
T11-12
What can result in anterior spinal artery syndrome (beck syndrome)?
An aortic cross-clamp placed above the artery of adamkiewicz (can cause ischemia to the lower portion of the anterior spinal cord)
Classic s/s of anterior spinal artery syndrome (4)
- Flaccid paralysis of LE’s
- Bowel and bladder dysfunction
- Loss of temp and pain
- Preserved touch and proprioception
What is preserved in beck’s syndrome? (anterior spinal artery syndrome)
Touch and proprioception
What is the radicularis magna?
The Artery of Adamkiewicz
Generally speaking, the (anterior/posterior) cord contains (motor/sensory) neurons
anterior cord = motor neurons
posterior cord = sensory neurons
The corticospinal tract is perfused by the (anterior/posterior) blood supply.
anterior (corticospinal/motor)
beck syndrome = flaccid paralysis of LE’s
Autonomic motor fibers are perfused by the (anterior/posterior) blood supply
anterior
beck syndrome = bowel and bladder dysfunction
The spinothalamic tract is perfused by the (anterior/posterior) blood fupply
anterior (spinothalamic = pain and temperature)
beck syndrome = loss of pain and temp
The dorsal column is perfused by (anterior/posterior) blood supply
Posterior (dorsal column = touch and proprioception)
Beck syndrome = preserved touch and proprioception bc thats supplied by the posterior circulation and beck syndrome is anterior circulation distruption
What are 3 spinal pathways that are supplied by the anterior spinal artery?
- Corticospinal (motor) - A fibers (A alpha)
- Spinothalmic (pain&temp) (A-Delta and C)
- Autonomic motor fibers (bowel and bladder) (b fibers)
What spinal pathway is supplied by the posterior spinal artery?
The dorsal column (touch and proprioception)
Sensory neurons from the periphery enter the spinal cord via the _____.
Motor and autonomic neurons exit via the _________
dorsal nerve root (sensory)
Ventral nerve root (motor and autonomic)
What is a collection of cell bodies that reside outside the CNS?
what about inside the CNS?
outside = ganglion
inside = nucleus
What laminae are sensory, motor, and central commisure (cross-over) area
1-6 = sensory (dorsal gray matter) 7-9 = motor (ventral gray matter) 10 = central commisures (crossover area)
What part of the spinal cord contains the axons of the ascending and descending tracts?
the white matter
The gray matter is larger in what 2 specific regions of the spinal cord and what do they contain/supply.
- C5-C7 - contain cell bodies for neurons that supply the upper extremities
- L3-S2 - contain cell bodies for the neurons that supply the lower extremities
What contains the axons of the ascending and descending tracts?
White matter
What is the white matter divided into?
Dorsal, lateral, and ventral columns
Match the sensory tracts:
- Dorsal Column
- Tract of Lissaur
- Lateral spinothalmic tract
- ventral spinaothalmic tract
- pain and temp (2)
- fine touch and proprioception
- crude touch and pressure
*bonus if you can list the associated fibers
- Dorsal Column
>fine touch and proprioception
(A-alpha = proprioception)
-Tract of Lissaur
>pain and temp
(A-delta and C fibers)
-Lateral spinothalmic tract
>Pain and temp
(A-delta and C fibers)
-ventral spinothalamic tract
>Crude touch and pressure
(A-beta = touch and pressure)
What are the 2 motor tracts and what do they transmit?
Lateral corticospinal tract (limb motor)
Ventral corticospinal tract (posture motor)
The ascending and descending tracts of the spinal cord contain what part of the neuron?
The axon (makes up the white matter)
T/F - the dorsal column transmits nociceptive input to the thalamus
False!
-The anterolateral system
The dorsal column is a (1-2-3) neuron sensory pathway that transmits what 4 things
3-neuron sensory pathway
transmits:
- Fine touch
- Proprioception (A-Alpha)
- Vibration (A-beta)
- Pressure (A-beta)
Which spinal system is capable of two-point discrimination?
Dorsal Column Medial Lemniscal System
T/F- the dorsal column medial lemniscal system transmits sensory information faster than the anterolateral system
True
Describe transmission through the Dorsal Column-Medial lemniscal system
1st order neuron (A-alpha or A-beta) enters DRG and ascends the ipislateral side
*synapses with 2nd in the medulla > crosses to contralateral side & ascends
> thalmus *synapses with 3rd order neuron & ascends to the somatosensory cortex in the parietal lobe
Match:
Merkel’s discs
Pacinian corpuscles
Ruffini’s endings
Meissner’s corpuscles
- Vibration
- Proprioception
- Continous touch
- Prolonged touch and pressure
- 2 point discrimination touch and vibration
Merkel’s discs
>Continuous touch
Pacinian corpuscles
>Vibration
Ruffini’s endings
>Prolonged touch and pressure (its never going to END)
>proprioception
Meissner’s corpuscles
>2 point discrimination touch and vibration
Which pathway transmit afferent nociceptive input to the brain?
A. Medial lemniscal system
B. Anterolateral system
C. Corticospinal tract
D. Tract of Lissauer
B. Anterolateral system
(DMLS)- transmits fine touch, proprioception, vibration and pressure
(Lissauer) - relays sensory info
(corticospinal) - transmits motor impulses
Anterolateral system AKA
spinothalamic tract
Anterolateral system transmits what 6 sensations
- Pain
- Temp
- Crude touch
- Tickle
- Sexual sensations
- Itch
*the kinky tract = anterolateral
Describe transmission through the anterolateral system (ventrolateral)
1st order neuron (A-delta or C) enters DRG and may ascend/descend 1-3 levels on ipislateral side in the tract of lissaur before synapsing with 2nd
*synapses with 2nd in the substantial gelatinosa (rex lamina 2) > crosses to contralateral side of spinal cord & ascends via the lateral or antero/ventral spinothalmic tracts
> *synapses with 3rd order neuron in RAS and thalmus & ascends to the somatosensory cortex in the parietal lobe
Neopinothalmic tract =
Lateral spinothalmic tract (transmits pain and temp)
Paleopsinothalmic tract =
Anterior (ventral) spinothalmic tract (transmits crude touch and pressure)
Injury to the corticospinal tract above the level of decussation in the medulla will result in (select 2)
- flaccid paralysis
- contralateral paralysis
- ipsilateral paralysis
- spastic paralysis
- spastic paralysis
- contralateral paralysis
(injury above decussation = spastic paralysis on the contralateral side)
Pyramidal tract =
Corticospinal tract
All motor pathways outside of the corticospinal tract are collectively known as what
the extrapyramidal tract
Upper motor neurons begin in the _______ and synapse with the lower motor neurons where?
Whereas lower motor neurons begin in the ______ and end where?
begin in the cerebral cortex
- synapse with lower motor neurons in the ventral horn of the spinal cord
- lower motor neurons begin in the ventral horn & end at the NMJ
UPPER motor neuron injury ABOVE/below the level of decussation results in what?
2 examples of upper motor neuron disease
UPPER ABOVE: Spastic, contralateral paralysis
UPPER BELOW: spastic ipsilateral paralysis
-CP & ALS
What does lower motor neuron injury result in and how does it present?
ipsilateral flaccid paralysis with impaired reflexes
______ neurons exit the precentral gyrus of the frontal lobe, pass through the internal capsule and then travel inferiorly through the pyramids of the medulla
motor neurons
The fibers that innervate the LIMBS cross over to the contralateral side in the ________ and then desecend the spinal cord via which tract
medulla
- LATERAL corticospinal tract
- think they cross so they go lateral – LATERAL LIMBS
The fibers that innervate the AXIAL MUSCLES … how do they descend?
*Where do they cross?
They remain on the IPSILATERAL side as they descend via the VENTRAL corticalspinal tract
VIA
Ventral
Ipsilateral
Axial muscles
*they crossover to the contralateral side of the spinal cord wehn the yreach the cervical or upper thoracic area
What does upper motor neuron injury result in?
Contralateral spastic paralysis and hyperreflexia
Upper motor neurons pass messages from where to where?
brain to spinal cord
cell bodies of upper motor neurons orginate wehre?
in the cerebral cortex
Why spastic paralysis and hyper-reflexia with upper motor neuron injury?
Bc normally there is a subset of neurons in the corticospinal tract that inhibit the lower motor neurons from firing to frequently;
this mechanism is blocked with upper motor neuron injury > spastic paralysis and hyperreflexia (CONTRALATERAL)
What test assesses the integrity of the corticospinal tract?
-what indicates and constitutes a negative/positive test?
The babinski test
- negative test = intact CST: firm stimulus to the underside of the foot produces a DOWNWARD mortion of all toes (down, negative test = good)
- positive test = damage to the CST; a firm stimulus to the understide of hte foot produces an upward extention of the big toe with fanning of other toes (Up = positive test = bad)
- it’s good if your toes curl in the bedroom
T/F- Babinski sign is absent with lower motor neuron injurty
true
How does lower motor neuron injury present?
Ipsilateral flaccid paralysis and impaired reflexes
where do cell bodies of lower motor neurons orginate?
ventral horn
Lower motor neurons pass messages from where to where?
Spinal cord to the muscles
How are evoked potentials produced?
By applying a current to a neural pathway
(SSEP/MEP) monitor the integrity of the (dorsal column medial lemniscus/corticospinal tract)
SSEP = dorsal MEP = corticospinal
What perfuse(s) the dorsal column medial lemniscus tract? The cortical spinal tract?
Dorsal =The posterior spinal arteries
Corticospinal = anterior spinal artery
Where does the upper motor neuron begin and end
cerebral cortex > ventral horn of spinal cord
Where does the lower motor neuron begin and end?
ventral horn > NMJ
Which findings are MOST likely to occur during hte acute phase of spinal cord transection at C7?
A. Autonomic hyperreflexia and hypothermia
B. Bradycardia and hypothermia
C. Tachycardia and hypotension
D. Hypothermia and tachycardia
B. Bradycardia and hypothermia
- patient with an acute C7 transection will experience neurogenic shock.
Patients with an acute ____ transection will experience neurogenic shock
C7
Neurogenic vs hypovolemic shock s/s
Neurogenic = bradycardia, hypotension, hypothermia + pink/warm extremities
Hypovolemic = tachycardia, hypotension + cool, clammy extremities
What are the most common causes (4) and most common site of SCI?
- MVI
- fall
- assult
- sports injury
*C7 (neurogenic shock- bradycardia, hypotension)
Complete SCI damages the (upper/lower) motor neurons:
acute phase sx vs later phase sx
upper motor neurons
acute phase = flaccid paralysis
later= spasticity
What are the major causes of morbidity and mortality in patients with cervical and upper thoracic lesions (2)
ineffective alveolar ventilation & inability to clear pulmonary secretions
T/F- avoid sux in patients with SCI
True - after 24 hours after injury due to upregulation of extrajunctional receptors
T/F- the higher the SCI, the less degree of hemodynamic instability
False - greater instability
Explain the decreased BP with neurogenic shock
decreased SNS tone
> vasodilation
> venous pooling
> decreased CO & BP
Explain the bradycardia with neurogenic shock
impaired cardioaccelerator fibers (T1-T4)
>unopposed cardiac vagal tone
>bradycardia and reduced inotropy
Explain hypothermia with neurogenic shock
decreased SNS tone
>vasodilation
>cutaneous heat loss
>hypothermia
SCI - which NMB agent should you use - nondepolarizer or depolarizer
NON-depolarizer
-there will be upregulation and depolarizers will cause massive K release
A patient with a 2-year-old C7 spinal cord transection presents for a cysto under GA. Insertion of the cystoscope causes the HR to decrease from 75 to 30….which statements are most likley to be true (select 2)
A. Ephedrine is a better option than atropine
B. Nitroprusside is a better option than hydralazine
C. The patient is at risk for ICH
D. The Bezold-Jarisch reflex caused the heart rate to decrease
B. Nitroprusside is a better option than hydralazine
C. The patient is at risk for ICH
-the patient experiencing autonomic hyperreflexia (AH) will vasodilate ABOVE the level of injury and vasoconstrict BELOW the level of injury (risk of severe HTN)
-consequences of HTN
>bradycardia via the BRR
>tx with anticholinergic
> treat HTN promptly- can cause stroke, LV failure and pulm edema
> nitroprusside will take effect much sooner than hydralazine (onset 10-20 mins)
After spinal shock phase ends (________[timeframe]), there is a return of sympathetic reflexes (above/below) the level of injury, placing patients at risk for what?
1-3 weeks
below level of injury
autonomic hyperreflexia
Typical presentation of autonomic hyperreflexia (2)
Hypertension
Bradycardia
Up to 85% of patients with injury above level ______ will develop autonomic hyperreflexia
T6 - wow that’s a lot
-esp if majority of SCI is C7
What conditions increase the risk of autonomic hyperrelfexia? (4)
Bladder catheritzation surgery (cysto/colonoscopy), bowel movement,
cutaneous stimulation,
child birth
After SCI, t he sympathetic nerves (above/below) the level of injury do not vasodilate in response to the baro-receptor response
s/s?
Below
-HTN > HA and BV
-Malignant HTN >stroke >seizure >LV failure >dysrhythmias >pulm edema >MI
Reflex vasodilation ABOVE the level of spinal cord injury will result in what symptom?
nasal stuffiness
T/F: patients do not have sensation BELOW the level of SCI
True - however, stimulation to the affected areas can elcit autonomic hyperreflexia
Best type of anessthetic fo SCI and preventing risk of autonomic dysreflexia
GA or spinal (>epidural)
3 steps in treating HTN in the patient at risk for AH
- Remove stimulus
- Deepen anesthetic
- Administer a rapid-acting vasodilator such as sodium nitroprusside
T/F: adding lidocaine jelly to the cystoscope or foley catheter prevents AH
False
T/F: Sux is contraindicated i npatients with chronic SCI
true
What is autonomic dysreflexia?
an involuntary reaction to external stimuli in patients with existing SCI.
-Increased SNS response below the level of SCI.
Consequences of amyotrophic lateral sclerosis include all of the following EXCEPT:
A. Hyperkalemia with sux
B. Cardiomyopathy
C. Risk of pulmonary aspiration
D. Increased sensitivity to nondepolarizing NMBs
B. Cardiomyopathy
- ALS does not affect cardiac muscle
- bulbar muscle weakness increases risk of aspiration
- extrajunctional receptors at the NMJ can cause life-threatening hyperkalemia
ALS causes progressive degeneration of (upper/lower) motor neurons in the corticospinal tract
both
upper motor neuron involvement presents as: spasticity, hyperreflexia, and loss of coordination
lower motor neuron involvement presents as: muscle weakenss, fasiculations and atrophy.
What motor neuron disease affects skeletal and cardiac muscle where patients commonly have associated cardiomypoathies and CHF
Friedreich’s ataxia
T/F - patients with ALS have intact sensory function
True - disease just affects motor neurons in the corticospinal tract - not sensory
Most common cause of death in ALS
resp failure
T/F - Sux is contraindicated in ALS patients
true - risk of lethal hyperkalemia
pts with ALS have an (increased/decrease/no change) in sensitivity to NONDEPOLARIZING neuromusuclar blockers
increased sensitivity
think they are already weak- wont need as much
Why are ALS patients at risk for aspiration?
due to bulbar muscle dysfunction
changes in resp status in ALS patients(volume/capacity changes and why)
decreased VC and minute ventilation due to chest weakens
Eitiology of ALS
unknown
What is autonomic dysfunction evidenced by in those with ALS?
orthostatic hypotension and resting tachycardia
What is the only drug that reduces mortality in patients with ALS and what kind of drug is it?
Riluzole - NMDA antagonist
What is the optimal anesthetic plan for someone with ALS
no evidence supports a clear benefit to any particular anesthetic technique over another.
What NMBs should be avoided in the patient with ALS?
All of them
>SUX = hyperkalemia >NDMR = very sensitive to
- if NMDR are given, consider the need for postop ventilation
Administration of roc during a complex spinal surgery will impede the monitoring of:
A. Dorsal column
B. Corticospinal tract
C. Tract of Lissauer
D. Anterolateral system
B. Corticospinal tract
The tract of Lissauer is a component of which spinal pathway?
A. Corticospinal tract
B. Spinothalamic tract
C. Rubrospinal trct
D. Dorsal column
B. Spinothalamic tract
Which type of mechanoreceptor allows pts who are blind to read braille?
A. Pacinian corpuscles
B. Ruffini’s endings
C. Merkle’s Discs
D. Meissner’s Corpuscles
D. Meissner’s Corpuscles
(2 point discrimination)
*being blind isnt as messy (meissi) as you think, their two-point descrimination allows them to read braille better than any of us can
A pt recovering from an open AAA has paraplegia with preserved sensory function. Blood flow to which spinal artery was MOST likely impaired by the aortic cross-clamp:
A. Anterior sulcal artery
B. Posterior spinal artery
C. Lumbar artery
D. Great radicular artery
D. Great radicular artery
An aortic cross clamped placed above the artery of Adamkiewicz (great radiuclar artery) can cause ischemia to the (upper/lower) portion of the (antterior/posterior) spinal cord
lower portion of the anterior spinal cord
- Becks syndrome
- flaccid paralysis of LE’s
- bowel and bladder dysfx
- loss of pain and temp
- preserved touch and proprioception
A quadriplegic patient presents for a small bowel resection. Five mins after foley insertion the patient becoems severely hypertensive and bradycardic. What is the MOST likely cuase of this complication?
A. Neurogenic shock
B. Anaphylaxis
C. MH
D. Mass Reflex
D. Mass Reflex
AKA: autonomic hyperreflexia
Which pathwya is involved in the transmission of pain?
A. Spinothalamic tracts
B. Corticospinal tracts
C. Dorsal columns
D. Autonomic motor fibers
(what is another name for the answer)
A. Spinothalamic tracts
*Anterolateral system
Which spinal cord pathwya is perfused by the posterior spinal arteries?
A. Medial lemniscal system
B. Autonomic motor fibers
C. Spinothalamic tract
D. Corticospinal tract
A. Medial lemniscal system
(dorsal column)
Spinothalmic, corticospinal, and autonomic motor fibers recieve their blood supply from the anterior spinal artery.
Spinothalmic, corticospinal, and autonomic motor fibers recieve their blood supply from what
the anterior spinal artery
A quad presents for dorsal rhizotomy. What induction agent should be avoided?
Sux
