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Spinal Cord Injury
- 11,000 new cases annually
- 50% of SCI involve the cervical spine
- Before WWII; life expectancy up to 10 years following injury
- Cause of death: renal failure & sepsis
- Improved treatment strategies
- Now the SCI patient life expectency only 5 years less than the general population
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Tetraplegia aka Quadriplegia
- Paraysis of both arms and legs
- If death occurs in a patient with tetrapledia is is usually realted to compromised respiratory function
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Etiology & Pathophysiology
- Greatest risk for SCI are males between age of 16-30 years
- 78% of people with SCI are male
- Most common age of injury is age 19 (male)
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Causes of SCI Trauma
- MVA - 50%
- Falls - 24%
- Vilolence - 11%
- Sports Injuries - 9%
- Misc - 6%
- Note: In large urban areas gunshot wounds may surpass falls as a cause of SCI
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Initial Injury Causes
- Cord compression by bone displacement
- Interuption of blood supply to the cord
- Traction resulting from pulling on the cord
- Penetrating trauma, such as a gunshot wound or stab wounds can result in tear or traction
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Primary Injury
- The initial mechanical disruption of axons as a result of stretch or laceration
- Small perivascular hemorrhages, especially in gray matter of cord - ischemia/infarction
- Edema may produce transient loss of function
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Secondary Injury
- Occurs minutes to hours after primary injury
- White matter edema
- Microcirculation of the cord is impaired
- Release of norephinephrine/serotonin/dopamine/histamine
- --Vasospasms and further reduction in circulation
- --Ischemia/necrosis/paralysis=irreversible
- Because secondary injury occurs over time, the exent of injury may not be most accurately determined until after 72 hours or more
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Spinal Shock
- Occurs in about 50% of people with SCI
- Characterized by decreased reflexes, loss of sensation, and flaccid paralysis below the injury site
- Lasts days to months and may mask postinjury neurologic function
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Neurogenic Shock
- Due to the loss of motor tone caused by the injury
- Characterized by hypotension and bradycardia
- --Loss of sympathetic nervous system innervation causes peripheral vasodilation, venous pooling and decreased CO
- Generally assocaited with a cervical or high thoracic injury
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Classification of Spinal Cord Injury
- Mechanism of Injury
- Skeletal and neurologic level of injury
- Completeness or degree of injury
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SCI - Mechanisms of Injury
- Flexion: injury of the cervical spine reptures the posterior ligaments
- Hyperextension: injury of the cervical spine reptures the anterior ligaments
- Flexion-Rotation: most unstable of all injuries because the ligamentous structures of that stabilize the spine are torn. This injury is most often associated with the most severe neurological deficits.
- Extension-Rotation:
- Compression: compression fractures crush the vertebrae and force bony fragments into the spinal canal
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SCI - Level of Injury
- Skeletal Level: is the vertebral level where there is the most damage to vertebral bones and ligaments
- Neurologoc Level: the lowest segment of the spinal cordwith normal sensory and motor function on both sides of the body
- --The level of the injury can be cervical, thoracic or lumbar.
- --Cervical and lumbar are the most common b/c these are associated with the most flexiblity and movement
- --If the cervical cord is involved it can result in tetraplegia, however if damage is high on the cervical cord the arms are rarely completely paralyzed
- --If the thoracic or lumbar cord is damaged, the result is paraplegia
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