Lecture SCI - Mechanisms of Injury and Acute Management Flashcards
What are the 3 mechanisms of Injury for SCI
Compression
Shearing
Distraction
How could a compression injury happen
Can occur with a diving or football tackling injury
- Axial blow to the skull
- Often coupled with a flexion injury
What does a compression injury do to the bones
Leads to a concave (burst) fx of the bony end plate
-Bony fragments enter the cord and rupture intervertebral disc
How do compression fractures cause SC injuries
The bony fragments break off and travel into the spinal cord
What are shearing forces
They move side to side.
Occur when a horizontal force is applied to the spine relative to an adjacent segment, and flexion/extension is blocked
What part of the spine are more prone to damage from shearing force
Most common in the thoracic spine
What type of damage is the result of a shearing force
Results in ligamentous damage and often results in abnormal axonal transmission
Is distraction a common injury
not really, this is the least common type of SCI, it occurs with whiplash and that is a hyperextension injury.
hyperextension injuries are not common because of the spinous processes
What does distraction do to the axons
Can result in longitudinal axonal shearing
Is it important to reduce secondary cord damage
SCI
YES! Damage to the cord is rarely the result of the initial trauma, and is more commonly due to secondary effects of the injury
Name 5 types of secondary effects from a SCI
Ischemia – damaged spinal arteries & vasospasms
Inflammation
Physical disruption of axons - stretching of the axon
Hemorrhage or edema
Ion derangement – altered membrane permeability leads to abnormal concentrations of K+ & Na+ (and you would want to prevent the neuron cascade)
When there is traumatic injury to the SC this causes what type of responses in the body and what is this called
Spinal shock - happens when you have a traumatic injury to the spinal cord, the body responds by sending inflammation to that area.
That inflammation causes depression of a lot of he reflexes in that area and the loss of our sensory motor function below it (it kind of creates a wall so it can protect the area)
Now that this area is protected there will be ionic disruption, axon disruption, and flaccid paralysis (loss of all sensorimotor functions) below the level of injury
You also have vasodilation which leads to hypotension and bradycardia. This results in a decrease in CO.
You also have venous pooling because the muscle pump is not effective
What is spinal shock - definition
A state of transient physiological reflex depression of cord function below the level of injury with associated loss of all sensorimotor functions.
What are some signs and symptoms of spinal shock
Flaccid paralysis Areflexia Vasodilatations 🡪 Hypotension Bradycardia ↓ in cardiac output Venous pooling
How long does spinal shock last and what might this tell you about a patient’s prognosis
Can last for hours or for weeks - but the sooner it resolves the better the prognosis
typically resolves in 24 hours
What does spinal shock do to the cardiovascular system
It causes vasodilation which leads to hypotension and bradycardia. This results in a decrease in CO.
You also have venous pooling because the muscle pump is not effective
How would you test for Spinal Shock
An early sign of resolution is the presence of the bulbocavernosus reflex
(+) reflex indicates the end of spinal shock, and may precede the presence of DTRs or spasticity for several weeks
If the reflex is (+) without later sensory or motor return, a complete lesion is indicated
What is the bulbocavernosus reflex
During digital rectal exam, pressure is applied to the glans penis or the glans clitoris by pulling on the catheter tube
Contraction around the examining digit = (+) reflex
(+) reflex indicates the end of spinal shock, and may precede the presence of DTRs or spasticity for several weeks
If the reflex is (+) without later sensory or motor return, a complete lesion is indicated
-a positive reflex is a good sign
What are the first 3 steps of Acute Management of SCI
- Pharmacologic management
- Surgical realignment and stabilization
- Prevention of secondary complications
Pharmacologic management of SCI, What are the two main and there are 3 others
2 Main:
- Methylprednisolone
- GM1 Ganglioside
Others
- Interleukin-10
- Glutamate (AMPA) Receptor Blockers
- 4-Aminopyridine
What is the standard of care for SCI
Methylprednisolone
Methylprednisolone is, does and when should it be administered
“Standard of care”
Anti-inflammatory steroid – prevents swelling & damage at injury site
↓ the secondary effects
Administered in high doses & must be given within 8 hours of the onset of injury
What does GM1 Ganglioside do
Evidence suggests that it may augment nerve growth & induce regeneration & sprouting
LEs appeared to be more affected by the drug than the UEs
Recovery appeared to be primarily due to restoration of muscle function in initially paralyzed muscles as opposed to muscles gaining greater strength
What does Interleukin-10 do
potent anti-inflammatory; unclear about correct amount/combo needed?
What does Glutamate (AMPA) Receptor Blockers do
neurotransmitter; decreases cell from firing in excess.
Because of active role that glutamate plays in secondary effects
What does 4-Aminopyridine do
improves function in surviving spinal cord nerve cells long after the injury.
(supports the existing cells in the spinal cord)
Surgical management of SCI
Surgical stabilization
Decompression
What is surgical stabilization in regards to SCI
Injured spinal column is stabilized to prevent further damage to the cord and/or nerve roots
How does decompression help SCI
Decompression has been shown to ↑ neurologic recovery
Research has shown that recovery ↓’s with ↑’ing time of compression & with ↑ compressive forces
When people to have surgery for a SCI (2 Types)
- Traction: Gardner-Wells Tongs
- Internal Fixation
Traction: Gardner-Wells Tongs is used for
Used acutely to provide traction
Inserted into the skull, with weights attached to provide traction
↓ dislocation and maintain alignment
Surgical Management of SCI:
Internal Fixation is used for
(stabilizes the region)
Fusion of unstable joint(s) with hardware and/or bone autografts
Harrington rods are the most common for thoracic/lumbar injuries
Recent advances in transpedicular screws improve fixation
Pedicle is the strongest site posteriorly for fixation
What are some types of non-surgical managements for a SCI (name 2)
- Halo Traction
- Orthoses (worn for 6-12 weeks)
What are some advantages to halo traction
Advantages
- Early mobility
- Avoidance or delay of surgery
What are some disadvantages to halo traction
Disadvantage
- Skin breakdown
- Dysphagia
- TMJ problems
- Limited UE movement
Ambulation: Realistic goals and setting expectations for AIS Grade A
- 7% negative predictive probability for independent ambulatory ability
- 1% of patients with a complete injury improved to incomplete by 5 years
Ambulation: Realistic goals and setting expectations for AIS Grade B and C
inconsistent but postinjury somatosensory evoked potentials in the tibial nerve strongly related to ambulatory outcomes
Ambulation: Realistic goals and setting expectations for AIS Grade D
97.3% positive predictive probability of regaining independent ambulation at 1 year
