Spinal Cord

Question 1

How does polio affect the spinal cord?

Answer 1

By damaging alpha motor neurons in anterior & ventral spinal cord resulting in progressive paralysis in the muscles that are inner step by those neurons

Question 2

How does syphilis affect the spinal cord?

Answer 2

Damage in the dorsal ganglia resulting in proprioception issues which can lead to death

Question 3

How does multiple sclerosis affect the spinal cord?

Answer 3

By damaging myelin sheaths of the nervous system resulting in degeneration of the spinal cord

Question 4

Most spinal cord injuries are associated with what?

Answer 4

spinal fractures from a mechanical impact

Question 5

What are the 3 main types of bony vertebrae injuries?

Answer 5

compression fracture, dislocation, fracture-dislocations

Question 6

How does the Denis classification system group spinal fractures using the three-column concept?

Answer 6

fracture occurring in the:

anterior column (front half of vertebral body, disc & anterior longitudinal lig.)
middle column (back half of vertebral body, disc & posterior longitudinal lig.)
posterior column (pedicles, lamina, facet joints & spinous processes)

Question 7

What is significant about damage occurring to the middle column?

Answer 7

the middle column is key to spine stability and there is more likely to be damage to the spinal cord due to its proximity

Question 8

Describe the MOI of a compression fracture.

Is a compression fracture usually more or less severe than other vertebrae bony injuries?

Answer 8

sudden downwards force usually due to a fall in the elderly

Usually less severe than other fractures however the worst-case scenario is a burst fracture

Question 9

What condition can make someone more vulnerable to a compression fracture?

Answer 9

osteoporosis (weak bones)

Question 10

Describe the MOI of a vertebra dislocation.

Answer 10

a shearing force which causes ligaments and/or intevertebral discs to be stretched or torn possibly resulting in misalignment of the vertebra

Question 11

Describe the MOI of a fracture-dislocation.

Answer 11

a combination of compression fracture and dislocation (a sudden downwards force + a shearing force)

Question 12

Out of the 3 kinds of vertebra bony injuries (fracture, dislocation & fracture-dislocation), which will typically be managed surgically? Why?

Answer 12

dislocation & fracture-dislocation due to the instability of the spine following these injuries

Question 13

What kind of imaging is required when diagnosing a spinal fracture and/or dislocation?

Answer 13

CT or MRI

Question 14

What is quadriplegia?

Answer 14

Impairment of the arm, trunk, lower limb & pelvic region due to a cervical spinal cord lesion

Question 15

What level of spinal cord injury would someone no longer be able to breath independently?

Answer 15

C4 & above

Question 16

What is paraplegia?

Answer 16

impairement to the trunk, lower limbs & pelvic region due to a lesion to the thoracic spinal cord or below

Question 17

What level of the spinal cord is most commonly injured and why?

Answer 17

C5, because it is the most mobile

Question 18

The dorsal column of the spinal cord carries what kind of information?

Answer 18

fine touch & proprioception

Question 19

‘Spinal shock’ can occur during the acute phase of an injury, what are the functions typically lost during this time?

How long can spinal shock last?

Answer 19

somatic reflexes
autonomic reflexes
autonomic regulation of blood pressure (hypotension)

several week s

Question 20

What does hypotonia refer to?

Answer 20

flaccidity often as a result of a lower motor lesion

this can also temporarily be seen in upper motor neuron lesions due to spinal shock

Question 21

What does hypertonia refer to?

Answer 21

spasticity as a result of an upper motor neuron lesion

Question 22

How does the Brain and Spinal Injury Centre (BASIC) system grade spinal cord injuries?

Answer 22

in degree of severity from 0 (normal) to 4 (most severe)

Question 23

What is the difference between primary injury and secondary injury?

Answer 23

Primary injury refers to the damage that occurs immediately due to trauma, there may be immediate cell death, neural disruption & vascular disruption

Secondary injury refers to damage that occurs after the fact (minutes to days to years later) and can include:

excitotoxicity
oedema & ischemia
oxidative stress
post-traumatic inflammation

Question 24

Compare apoptosis and necrosis in terms of what happens to their size, uptake, membrane & organelles

Answer 24

necrosis

size: multiple cells swell
uptake: cell contents ingested by macrophages with significant inflammation present
membrane: loses its integrity as lysis occurs
organelles:

apoptosis

size: individual cell shrinks
uptake: cell contents ingested by neighboring cells with no inflammatory response
membrane: blebbing occurs and apoptotic bodies form
organelles: mitochondria release pro-apoptotic proteins

Question 25

Do primary injuries typically involve cell necrosis or apoptosis? What about secondary injuries?

Answer 25

primary typically involves necrosis while secondary typically involves apoptosis

Question 26

Describe the mechanism of ischemia as a secondary spinal cord injury

Answer 26

restriction of blood flow past the area of injury results in a loss of oxygen and ultimately apoptosis of cells in that area

Question 27

Describe the mechanism of excitotoxicity as a secondary spinal cord injury

Answer 27

damaged cells release glutamate resulting in an excess of glutamate in the area

this causes overexcitement of neurons resulting in an excessive influx of calcium to the cell leading to excessive reactive oxygen species and ultimately apoptosis

Question 28

Describe the mechanism of inflammation as a secondary spinal cord injury including the order in which inflammatory cells turn up

Answer 28

immune cells enter the site of injury to clean up debris and prevent infection

this involves a peripheral acute phase response (APR) which brings inflammation cells to the site of injury that are not commonly within the spinal cord

excessive amounts of some of these inflammation cells can lead to poorer neurological recovery and outcomes

microglia>neutrophils>macrophages>lymphocytes

Question 29

Which immune cell is already typically found within the spinal cord?

Answer 29

microglia

Question 30

What occurs in the peripheral acute phase response (APR) to traumatic SCI?

Answer 30

Following trauma, extracellular vesicles are released into the bloodstream triggering the liver to mobilize leukocytes (neutrophils, macrophages & lymphocytes) to the site of injury

Question 31

What are the 6 key strategies to manage and repair spinal cord injuries?

Answer 31

Preservation of neural tissue
Preservation of white matter
Replacement of lost cells
Regrow damaged pathways 
Appropriately rewire & retrain new circuitry

Question 32

How can controlled SCI modeling on rats help us to understand possible treatment options for SCI’s in humans?

Answer 32

by being able to assess specific outcomes following treatment:

lesion extent (cavity size/scarring)
neuronal sparing (no. of cells remaining)
axonal sparing (no. of axons remaining)
myelinated tissue sparing (degree of myelination)
axonal conduction (function of axons)
apoptosis (no. of cells undergoing/about to undergo apoptosis)

Question 33

Would a compression fracture or dislocation-fracture result in more severe injury?

Answer 33

a translational/shearing force (which causes dislocation) is more likely to result in tearing of ligaments and other injuries than a sudden downward force (which causes compression)

also, a compression fracture usually affects the anterior column of the spine whereas a dislocation fracture often affects the middle column. The middle column is more proximal to the spinal cord making it more likely to result in neurological damage