Lecture 4: Spinal cord injury (minus first 12 slides) Flashcards
Pathogensis of SCI:
Blood flow changes
* Ischemia releated to reduced blood flow, damage to blood vessels and microhemorrages, hypoxia
Inflamamtion:
* Positive and negative effects
Demyelination
* Reduced rate of axonal firing, maturation of a scar around the lesion (positive and negative effects) - if a scar forms and becomes rigid, mobility can suffer around that area (can also be protective and sealing)
Grey Matter
* Loss, fluid-filled cyst (syrinx) forms or cord collapses
Dural scarring
* Causes permanent connection of cord to dura, no longer freely mobile
Neural function
* Impacted below injury level
* If its at C6 they’ll have C6 abilities
Neuropraxia
* Athletic injury, PNS nerve damage
Syringomyelia
* Can appear over time, cyst activation and gliosis of SC, syrinx forms, cyst cavity
* can cause pressure in areas we dont want
Fluid filled aera
* can cause area of pain and numbness and tingling
Think bruising of SC
* can lead to cell death
* Sensory/motor problems
* necrossis / hemorrhage
Syringomyelia
Neurologic disorder in which a fluid filled cyst (syrinx) forms within the SC
What does dural scaring do to the SC?
Makes it less mobile
Spinal cord is impacted will they be okay at the level of the lesion
Yes, if C6 is impacted you will be okay at the level of C6, its just everything below that thats the issue
Neuropraxia
Neuropraxia is a type of nerve injury characterized by a temporary loss of function in a nerve due to compression or stretching. This condition often results in symptoms like weakness, numbness, or tingling in the affected area. Neuropraxia typically involves no structural damage to the nerve itself, and recovery usually occurs within a few hours to weeks, depending on the severity and cause of the injury.
Trauma happens
* Arteries / veins are affected (blood supply)
* Cells are affected
* Impared breathing
* Vasodilation impared inotropy
All the leads to ischemia
Notice what happens to the vertebral artery when vertebrae are affected.
* so everything below this area will be affected
What makes the cord less mobile?
Dural scaring
SCI’s are classified according to if the are complete or incomplete.
SCI’s are classified by the neurologic level of injury
* Named by most caudal level with normal sensory and motor function bilatearlly
SCI injury that has lack of sensory and motor function in the lowest sacral segment
Complete injury
SCI that has preservation of sensory and/or motor function in the lowest sacral segment
Incomplete injury
How are SCI’s names?
Named by most caudal level with normal sensory and motor function bilatearlly
What are the two ways SCI’s are classified
1) Compleite or incomplete
2) Neurologic lvl of injury
Neurologic Level of Injury - NLI
* SCI named for neurologic level of injury - NLI
* American spinal injury association distributes and maintains the international standards of neurlogical classification of SCI
Identifies sensory and motor levels indiciative of the most rostrual spinal levels demonstrating unimpared function
* Rostral levels are unimpared (toward the head)
* Named by most caudal level bilatearlly that is unimpared
28 dermatomes are assessed bulatearlly using pinprick and light touch sensation, and 10 key muscles are assessed bulatearlly w/ MMT
* Results are summed to produce overall sensory and motor scores and are used in combination w/ evaluationof anal sensory and motor function as a basis for the deternubatuib if AIS ckassufucatuib
So you’re naming it based on the most caudal thats unimpaired bilatearlly, but testing the ones above to make sure they’re uninpaired
NLI extended
A clinical examination is conducted to rate sensation as follows
* 0 = absent
* 1 = impaired
* 2 = normal
Muscle function is rated from 0 (total paralysis) to 5 (normal-active movement, full ROM against significant resistance)
The presence of anal sensation and voluntary anal contraction area ssessed as Y/N
* So thats either yes or no because they either can or cannot do it
Bilatearl motor and sensory levels and the AIS are based on the results of these examinations
AIS (5 pound ordinal scale) classifies individuals from A (complete SCI) to E (normal sensory and motor function)
* NOTE: these are reserved for people that have had a SCI wouldnt rate eachother
Preservation of function in the sacral segments (S4-S5) is key for determining the AIS score
Knowledge check: No sensory function under level os SCI =
complete
Complete loss of sensory and motor function below the level of the lesion
Complete
Complete lesions are a result of spinal cord transection, severe compression or continusion, or extensive vascular dysfunction
Partial loss of sensory and mot function below the level of the injury
* The resulting motor or sensory function is called
Incomplete
Incomplete lesions often occur when there is a contusion produced by bone framents, soft tissue, or edema within the spinal canal
The resulting motor or sensory function is also called sparing
* Know that sparing is associated w/ incomplete lesions
ASIA SCALE
A = complete
B = Sensory incomplete (you have sensory but no motor below the NLI (neurologic level of injury)
C = Motor incomplete
* Less than half of key muscles below the level of NLI have a muscle grade >/3
D = Motor incomplete
* More than half of key muscles below the level of NLI have a muclge grade >/3
E = Normal - but they had to have prior deficits
So E is the best w/ A being the worst
ASIA (AIS) scale
ASIA Scale
The circled muscles are the 10 key muscles for testing motor function
ASIA SCALE
Asia Scale sensory testing
The dots on the person are where you’re going to be sensory testing
We have a C6 sensory and motor because that is the last spot on our scale where the person got a 5 bilatearlly
* and the last time they got normal sensory as well
* C6 is the last time they got a 2 for sensory bilatearlly and a 5 for motor bilatearlly
2 = max for sensory
This is an incomplete injury
Half of the key muscles are 3/5 or greater
D
Collection of signs and symptoms that do not indicate a specific cause, resulting from tumors or truma
Syndromes
Which syndrome
Anterior cord syndrome
Which syndrome
Central cord syndrome
Which syndrome?
Brown sequard syndrome
Which syndrome?
Cauda equina syndrome
Make sure you at least know the 3 main tracts
Anterior cord syndrome
* What kind of injuries (flxn or extension)?
* Interfers w/ what 3 things?
* What is it typically caused by
* This ischemia damages which portion of the cord.
* Are problems at, below, or above the level of the lesion
* Is it bilatearl or unilatearl?
* Why is conscious proprioception and light touch information spared?
Flexion injuries
Interferes w/ pain and temperature sensation and motor control
Typically caused by a disruption of blood flow in the anterior spinal artery
Ischemia damages the anterior 2/3 of the spinal cord (because thats what the anterior spinal artery supplies)
* affects the ascending spinothalamic tract and descending upper motor neurons
* Will also damage somas of lower motor neurons
Anterior cord syndrome interfers with nociceptive (pain) temperature sensation and with motor control below the level of the lesion - bilateraly (because the artery supplies the entire front of the cord)
NOTE: Because tracts that convey conscious proprioception and light touh information are located in the posterior cord, these functions are spared (DCML)
Central Cord Syndrome
* what kind of injuries (flxn or extension)
* At what level do they typically result, as a cause of what
* In small lesionswhat do you lose and why
* In larger lesions what do you lose
* Is it more sevre in UE or LE?
Hyperextension injuries
Usually occurs at the cervical level as a result of trauma
if the lesion is small, loss of nociceptive (pain) and temperature information occurs at the level of the lesion because spinothalamic fibers crossing the midline are interrupted
Larger lesions additionally impair upper limb motor function due to the medial location of upper limb fibers in the latearl corticospinal tracts - at/below level of lesion in UE
* More severe in UE than LE, variable degree of impairement in trunk/LE’s due to integrity of SC
She said to know: small lesion = problems at level of lesion, large lesion = upper body all together is impared
* Its going to be more severe impairement in upper body, but you’re going to see some degree of problems in LE as well
Brown Sequard Syndrome
* Disruption of what part of cord?
* Segmental losses are ipsilatearl or contralataeral?
* Below the level of sensation what is lost ipsilatearlly
* Below level of lesion what is lost contralaterally
Disruption to hemisection of the cord
Results from a hemisection of the cord
Segmental (spinal segment) losses are ipsilateral and include loss of lower motor enurons and all sensations
Below th elevel of the lesion, voluntary motor contorl (corticospinal), conscious proprioceptions, and light touch (DCML) are lost ipsilatearlly; nociceptive (pain) and temperature (spinothalamic) sensation is lost contralaterally
Cauda Equina Syndrome - also called medullaris syndrome
* what muscles are affected
* Why does spasticity and hyperreflexia occur?
* Are they common?
Indicates damage to the lumbar and/or sacral spinal roots, causing sensory impairment and flaccid paresis or paralysis of lower limb msucles, bladder and bowl
Spasticity and hyperreflexia do not occur because cauda equina lesions are below the spinal cord proper and thus upper motor neurons are intact
Complete cauda equina lesions are rare
This syndrome causes low back and lower limb pain and difficulty walking, execessive lordosos, scoliosis, problems with bowel and/or bladder contorl and foot deformities
* What can it be associated w/?
Tethered cord syndrome
Associated w/ spina bifida
KNOW: A good way to dilinate tethered cord from cauda equina is that tethered cord is onset as a child, that cord is thetehred to vertebral column area = low back pain, difficulty walking etc
* During development the vertebral column grows longer than the SC
* Infrequiently the SC becomes attached to surrounding structures during early development when its still growing down
* This tethering of the SC becomes stretched which damages the cord and the cauda equina
Lower motor signs (weakness, flaccidity) occur if the anterior cauda equina (because its the spinal nerves which are lower motor neurons?) is stretched. Upper motor neuron signs (abnormal reflex, paresis and changes in skeletal muscles) occur if the SC is excessively stretched
Posterior cord syndrome
* Common or rare?
* There is loss of what that leads to what?
* Which tract is affected?
Rare
Preservation of motr function, pain. There is loss of light touch and proprioception below the level of the lesion leading to severe gait deviations?
DCML affected (this is light touch, proprioception, and vibration)
Look at the right side of this picture
Knowledge check: Which syndrome has bilateral loss of pain, temp and motor control loss below the level of the lesion
Anterior cord syndrome (remember often caused by flexion injuries)
Changes that we see post SCI
Progressive paralytic scoliosis in a chronic SC patient. Happens due to lack of muscle tone and contorl following a SCI. Through being sedintary / sitting the SC goes into some curves they shouldnt go into
* This can impaire respiration if its severe (notice the 110 cobb angle)
A person has an episode of autonomic dysreflexia. What is it most likely releated to?
Always releated to some noxious stimulus below the neurlogic level of injury
However, 85% is urological
* think catheter backing up
* NOTE: We actaully lose the sense of the need to void w/ this kind of SCI, so thats why it backs up
This puts them at an increased risk of stroke so ints dangerous (because BP gets so high)
KNOW: In autonomic dysreflexia some noxious stimuli (think urinary) triggerys sympathetic reflex to the intermediolatearl grey columns
Lack of compensatory descending medullary parasympathetic response (vagal nerve)
generalized vasoconstriction
* Parasympathetic response occurs above the NLI (bradycardia and vasodilation)
* Sympathetic response continues below NLI
So they’re essentially getting both a sympathetic and parasympathetic response going on at the same time
What is the center for urination in the spine?
* What level is it?
Conus medullaris
* Upper vertebrae (L1/L2)
What is the leading cause of death among SCI w/ high cervical injury?
Remember, C4 is what innervates the diaphragm. So its Pneumonia because they can’t properly clear the lungs
What level is paraplegia?
T1 and below
NOTE: level of lesion insdicates the caudal most intact spinal segment that is the nurlogic level, not the vertebral level
