Lecture 2 Flashcards
What is a level of injury and the 2 (/3) forms?
Where the injury occurs and the restrictions due to this
- Tetraplegia
- Impairment or loss of motor and/or sensory function in upper and lower extremities, trunk, and pelvic organs
- Damage to segments C8 or higher (Cervical) - Paraplegia
- Impairment in both legs and pelvic organs
- Motor and sensory function normal in upper extremities
- Damage to thoracic, lumbar or sacral segments T1 or lower
*3. Cauda equina
- Technically not a spinal cord injury, but can fall under paraplegia since will look similar, and falls under the T1 spinal cord
What is the difference between an upper and lower motor neuron injury?
Upper:
- Damage to the descending tracts
- Either tetraplegia or paraplegia
- Upper motor neurons are from brain/stem to spinal cord where they synapse with the lowers
- Spinal cord injury*****
Lower:
- Lower motor neurons are those that come off spinal cord going towards effector muscle/organs
- Damage that occurs to the peripheral nerves in vertebral column
- Cauda equina injury*****
Is it possible to have lower motor neuron injury in spinal cord?
Yes, since possible for injury site to be cauda equina, with slight blow to the spinal cord as well.
What are the 2 functional differences between Upper and Lower motor neuron injuries?
Upper motor injury:
- Has spasms due to lower motor neurons being in tact to form somatic motor reflexes (even if not able to feel it)
- Some maintenance of muscle (Since even though no voluntary control, still has spasms)
Lower motor injury:
- Flaccid paralysis, meaning no spasms present since that reflex is cut off due to injury
- Profound atrophy since muscle cannot contract ever
What is muscle spasticity?
Being able to spasm due to slight passive stretch, or increase in muscle tone, sending afferent response to cauda equina and sending motor response back to contract/spasm
Upper motor neuron injury:
- Spastic paralysis below level of injury
Lower motor neuron injury:
- Flaccid paralysis
What is the difference between a complete and incomplete injury?
Complete:
- Both sensory and motor function are absent in the lowest sacral segments of the spinal cord (S4, S5)
- At some point in cord, no sensory or motor use (Not always at injury site)
Incomplete:
- Some sensory and/or motor function preserved below injury site, including sensory and/or motor function at S4 and S5 spinal cord segments
Complete vs. Incomplete innervation test of S4 and S5?
Finger in the anus, test if they can feel, and contract the sphincter
- If no motor or sensory, then complete
- If one or both, injury is incomplete
What are the 4 general classifications are spinal cord injury?
- Complete tetraplegia
- Absent motor and sensory function at some point before C8 - Incomplete tetraplegia
- Partial motor and sensory function beginning before C8 - Complete paraplegia
- Absent motor and sensory function at some point after T1 - Incomplete paraplegia
- Partial motor and sensory function somewhere after T1
Cauda equina/LMN injury would be paraplegia appearing similarly to complete
What is the neurological level in an ASIA exam?
The most caudal/lowest segment of the spinal cord with normal sensory and motor function on both sides of the body
- There may be different values for sensory vs. motor, and left vs. right
What is the sensory level in an ASIA exam?
The most caudal/lowest segment of the spinal cord with normal sensory function on both sides of the body
How would you perform the sensory function portion of the ASIA exam?
Test on the cheek at first since above spinal cord so will feel difference between sharp and dull
Eyes closed, start at c2 and ask whether sharp or dull, with 3 ways to answer:
- Can feel, and can tell whether sharp or dull (2/2)
- Can feel, but not as sharp of a feeling, or feel but dull not sharp, then 1/2
- 1/2 could also be hypersensitive at the area of injury, so could be dull feeling sharp - No feeling 0/2
Not testable:
- Possible severe injury (burns, casts, amputation, etc)
Test all 28 points on the left, and all 28 on the right, for both light touch with cotton ball and the pin prick for a max of 112
How do you interpret scores to determine the real sensory level?
Find the most caudal segment with normal sensory function on both sides
- Last segment with a 2/2 score for both sides
What is the motor level in the ASIA exam?
The most caudal/lowest segment of the spinal cord with normal motor function on both sides of the body
- May differ from one side to the other
What issue is presented with the motor level portion of the ASIA exam?
The functional test only provides information for the key 10 myotomes for both the right and left sides being
- Elbow flexors
- Wrist extensors
- Elbow extensors
- Finger flexors
- Finger abductors
- Hip Flexors
- Knee Extensors
- Ankle dorsiflexors
- Big toe extensors
- Ankle plantar flexors
This means that the trunk muscles aren’t tested (Would be too difficult) but therefore difficult to make very accurate reading of motor level
How would you perform the motor function portion of the ASIA exam?
Six point strength grading scale of each of the 10 myotomes:
0 - total paralysis/no contraction felt or seen
1 - palpable or visible contraction/flicker
2 - Active movement with full ROM, gravity eliminated/laying down
3 - Active movement with full ROM, against gravity/standing, off the body fighting gravity
4 - Active movement with full ROM, against moderate resistance/can fight slightly with resistance, not enough for full range resisted
5 - (Normal) Active movement with full ROM, against full resistance
How do you interpret scores to determine the real motor level?
Since one nerve can innervate multiple muscles and muscles are innervated by multiple nerves:
Segment is still defined as intact if graded as 3/5 or greater as long as the previous level was a 5/5 for both sides.
What needs to be done if the injury appears to affect the area between T1-L2 therefore motor level cannot be calculated?
It would be determined that although not fully accurate, the motor level is the same as the sensory level
What is the zone of partial preservation in the ASIA exam, and how do you determine it?
Only applicable for complete injury
- Since if incomplete, whole body is zone of partial preservation
Refers to dermatomes and myotomes caudal/lower than the neurological level that remain partially innervated
For example, if the right sensory level is C5, but some sensation extends to C8, then C8 is determined to be the right sensory ZPP block.
What are the 5 levels of severity in the ASIA impairment scale, and what are their descriptions (Most impaired/severe to least)
ASIA A:
- No sensory or motor function is preserved in the sacral segments S4-S5 (COMPLETE)
ASIA B: Sensory but not motor function is preserved below the neurological level and includes the sacral segments (INCOMPLETE)
ASIA C: Sensory and motor function is preserved below the neurological level (Including S4-5) and more than half of the muscles below the neurological level have a muscle grade LESS THAN 3 (INCOMPLETE) 1, or 2
ASIA D: Sensory and motor function is preserved below the neurological level (Including S4-5), and at least half of the muscles below the neurological level have a muscle grade MORE THAN OR EQUAL TO 3 (INCOMPLETE) 3, 4, or 5
ASIA E: Normal sensory and motor function
What are primary mechanisms of spinal cord injury?
Traumatic accident which causes damage to the
- vertebrae
- spinal cord
- blood supply to the spinal cord
Non-traumatic causes
- infection
- loss of spinal cord blood supply
- radiation
What are secondary mechanisms of spinal cord injury?
Within hours following the initial trauma the spinal cord undergoes progressive tissue destruction
- May last several days to a month
Results in spindle shaped area of necrotic/dead tissue (Cyst) that may span over several cord segments
- Can make injury go from incomplete to complete, or just bad to worse
What are the 4 types of secondary mechanisms in spinal cord injury?
- Ischemia
- Inflammation
- Ion-derangement
- Apoptosis
What are the characteristics of Ischemia? (Secondary mechanisms of SCI)
- Damage to arteries and arterioles that supply the cord
- Vasospasm due to neuron contents bursting, causing loss of norepinephrine (Vasoconstrictor) causing a spasm, and cutting blood supply
- Edema
- 15–30 seconds of lack of O2 (Anoxia) may cause irreversible damage
What are the characteristics of inflammation? (Secondary mechanisms of SCI)
Acute inflammation causes inflammatory cells to attract to the initially injured tissue
-This causes phagocytosis (eating dead tissue)
- Causes free radical production filling area (Healing cells, end up eating healthy tissue)
- This causes damage to surrounding healthy tissue
Makes injury larger than at the start
