Spinal Cord Flashcards
How does polio affect the spinal cord?
By damaging alpha motor neurons in anterior & ventral spinal cord resulting in progressive paralysis in the muscles that are inner step by those neurons
How does syphilis affect the spinal cord?
Damage in the dorsal ganglia resulting in proprioception issues which can lead to death
How does multiple sclerosis affect the spinal cord?
By damaging myelin sheaths of the nervous system resulting in degeneration of the spinal cord
Most spinal cord injuries are associated with what?
spinal fractures from a mechanical impact
What are the 3 main types of bony vertebrae injuries?
compression fracture, dislocation, fracture-dislocations
How does the Denis classification system group spinal fractures using the three-column concept?
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)
What is significant about damage occurring to the middle column?
the middle column is key to spine stability and there is more likely to be damage to the spinal cord due to its proximity
Describe the MOI of a compression fracture.
Is a compression fracture usually more or less severe than other vertebrae bony injuries?
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
What condition can make someone more vulnerable to a compression fracture?
osteoporosis (weak bones)
Describe the MOI of a vertebra dislocation.
a shearing force which causes ligaments and/or intevertebral discs to be stretched or torn possibly resulting in misalignment of the vertebra
Describe the MOI of a fracture-dislocation.
a combination of compression fracture and dislocation (a sudden downwards force + a shearing force)
Out of the 3 kinds of vertebra bony injuries (fracture, dislocation & fracture-dislocation), which will typically be managed surgically? Why?
dislocation & fracture-dislocation due to the instability of the spine following these injuries
What kind of imaging is required when diagnosing a spinal fracture and/or dislocation?
CT or MRI
What is quadriplegia?
Impairment of the arm, trunk, lower limb & pelvic region due to a cervical spinal cord lesion
What level of spinal cord injury would someone no longer be able to breath independently?
C4 & above
What is paraplegia?
impairement to the trunk, lower limbs & pelvic region due to a lesion to the thoracic spinal cord or below
What level of the spinal cord is most commonly injured and why?
C5, because it is the most mobile
The dorsal column of the spinal cord carries what kind of information?
fine touch & proprioception
‘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?
somatic reflexes
autonomic reflexes
autonomic regulation of blood pressure (hypotension)
several week s
What does hypotonia refer to?
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
What does hypertonia refer to?
spasticity as a result of an upper motor neuron lesion
How does the Brain and Spinal Injury Centre (BASIC) system grade spinal cord injuries?
in degree of severity from 0 (normal) to 4 (most severe)
What is the difference between primary injury and secondary injury?
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
Compare apoptosis and necrosis in terms of what happens to their size, uptake, membrane & organelles
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
Do primary injuries typically involve cell necrosis or apoptosis? What about secondary injuries?
primary typically involves necrosis while secondary typically involves apoptosis
Describe the mechanism of ischemia as a secondary spinal cord injury
restriction of blood flow past the area of injury results in a loss of oxygen and ultimately apoptosis of cells in that area
Describe the mechanism of excitotoxicity as a secondary spinal cord injury
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
Describe the mechanism of inflammation as a secondary spinal cord injury including the order in which inflammatory cells turn up
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
Which immune cell is already typically found within the spinal cord?
microglia
What occurs in the peripheral acute phase response (APR) to traumatic SCI?
Following trauma, extracellular vesicles are released into the bloodstream triggering the liver to mobilize leukocytes (neutrophils, macrophages & lymphocytes) to the site of injury
What are the 6 key strategies to manage and repair spinal cord injuries?
Preservation of neural tissue Preservation of white matter Replacement of lost cells Regrow damaged pathways Appropriately rewire & retrain new circuitry
How can controlled SCI modeling on rats help us to understand possible treatment options for SCI’s in humans?
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)
Would a compression fracture or dislocation-fracture result in more severe injury?
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
