Exam 3: Spinal Cord Injury Flashcards
What can cause a spinal cord injury?
38% motor vehicle collisions 30% falls 14% violence 9% sports injuries 9% other miscellaneous cases
SCI Etiology and Pathophysiology: Primary Injury
- SCI due to cord compression by:
- Bone displacement
-Interruption of blood supply - Traction from pulling on cord
- Bone displacement
- Penetrating trauma → tearing and transection
SCI Etiology and Pathophysiology: Secondary Injury
- Ongoing, progressive damage that occurs after initial injury
- Several theories exist on what causes ongoing damage
Secondary Injury: Several Theories exist on what can cause ongoing damage to the spinal cord
- Vascular changes (d/t hemorrhage, vasospasm, thrombosis, loss of autoregulation, breakdown of blood brain barrier and infiltration of inflammatory cells that cause ischemia, edema and cellular necrosis)
- Free radical formation, Lipid peroxidation, Release of glutamate and Uncontrolled calcium influx (can lead to neuronal cell death and reduced spinal cord flow)
- Apoptosis (can contribute to post-injury demyelination)
Events leading to secondary injury
- The resulting hypoxia reduces the oxygen levels below the metabolic needs of the spinal cord.
- Lactate metabolites and an increase in vasoactive substances, including norepinephrine, serotonin, and dopamine, occur.
- High levels of these vasoactive substances cause vasospasms and hypoxia with subsequent necrosis.
- Unfortunately, the spinal cord has minimal ability to adapt to vasospasm.
- Look at photo on slide!
Secondary SCI: Extent of damage and prognosis
- Within 24 hours, permanent damage may occur because of edema
- Extent of damage and prognosis for recovery most accurately determined 72 hours or more after injury
- Greatest improvement occurs in first 3 to 6 months following injury
*Read notes!!
What is spinal shock?
- May occur following acute SCI.
- Lasts days to weeks and may mask post-injury neurologic function.
Spinal Shock is characterized by
- ↓ Reflexes
- Loss of sensation
- Absent thermoregulation
- Flaccid paralysis below level of injury
Neurogenic Shock
- Results from loss of vasomotor tone due to injury.
- Associated with cervical or high thoracic injury (T6 or higher)
Neurogenic shock is characterized by
Hypotension and bradycardia
Neurogenic Shock: Loss of SNS innervation leads to
- Peripheral vasodilation
- Venous pooling
-↓Cardiac output
How is SCI classified?
- Mechanism of injury
- Level of injury
- Degree of injury
Major Mechanisms of SCI
- Flexion
- Hyperextension
- Flexion-rotation (most unstable because ligaments that stabilize the spine are torn; most often contributes to severe neurologic deficits)
- Extension-rotation
- Compression
*Look at image on slide 12
Level of Injury
- Skeletal versus neurologic level
- Level of injury may be: cervical, thoracic, lumbar or sacral.
Skeletal level injury
the vertebral level with the most damage to vertebral bones and ligaments
Neurologic Level Injury
- Is the lowest segment of the spinal cord with normal sensory and motor function on both sides of the body.
- The level of injury may be cervical, thoracic, lumbar, or sacral
Level of Injury: If cervical cord is involved,
- Paralysis of all four extremities occurs, resulting in tetraplegia (formerly quadriplegia).
- The degree of impairment in the arms following cervical injury depends on the level of injury.
- The lower the level, the more function is retained in the arms.
Level of Injury: If the thoracic, lumbar or sacral spinal cord is damaged, the result is
paraplegia (paralysis and loss of sensation in the legs)
Degrees of Injury include
Complete or Incomplete (Partial)
Degree of Injury: Complete
Total loss of sensory and motor function below level of injury
Degree of Injury: Incomplete (Partial)
- Mixed loss of voluntary motor activity and sensation
- Some tracts intact
C4 injury and above requires
Mechanical ventilation
What are five syndromes associated with incomplete injuries?
- Central cord syndrome
- Anterior cord syndrome
- Brown-Séquard syndrome
-Cauda equina syndrome - Conus medullaris syndrome
Incomplete SCI Central Cord Syndrome
- Damage to central spinal cord
- Most commonly cervical region and more common in older adults
Incomplete SCI: Anterior Cord Syndrome
- Damage to anterior spinal artery → compromised blood flow
- Typically results from flexion injury
Incomplete SCI: Brown-Séquard Syndrome** Biggest one on test!!
- Damage to one-half of cord
- Typically results from penetrating injury
Degree of Injury: Conus Medullaris Syndrome results from
Damage to conus medullaris (lowest portion of spinal cord)
Conus Medullaris Syndrome: Clinical Findings
- Motor function in legs may be preserved, weak, or flaccid
- Decrease in or loss of sensation in perianal area
- Areflexic bladder and bowel
- Impotence
- Pain is uncommon
Brown-Séquard Syndrome: Clinical Findings
- Ipsilateral loss of motor function and pressure, position, and vibration sense
- Contralateral loss of light touch, pain, and temperature sensation
Incomplete SCI Anterior Cord Syndrome: Clinical Findings
- Motor paralysis
- Loss of pain and temperature sensation below level of injury
Incomplete SCI Central Cord Syndrome: Clinical Findings
- Motor weakness and sensory loss
- Lower extremities are not usually affected
- Dysesthetic burning pain in upper extremities
Cauda Equina Syndrome results from
Damage to cauda equine (lumbar and sacral nerve roots)
Cauda Equina Syndrome: Clinical Findings include
- Asymmetrical distal weakness
- Flaccid paralysis of lower extremities
- Complete loss of sensation in saddle area
- Areflexic (flaccid) bladder and bowel
- Severe, radicular, asymmetric pain
Clinical Manifestations of SCI
- Related to level and degree of injury
- Incomplete → variable
- Sequelae more serious with higher injury
Manifestations of C4 Injury
- Tetraplegia
- Results in complete paralysis below the neck
Manifestations of C6 Injury
-Results in partial paralysis of hands and arms as well as lower body
Clinical Manifestations of T6 Injury
- Paraplegia
- Results in paralysis below the chest
Clinical Manifestations of L1 Injury
- Paraplegia
- Results in paralysis below the waist
ASIA Impairment Scale
- Classifies the severity of impairment resulting from SCI.
- It combines assessment of motor and sensory function to determine neurologic level and completeness of injury.
*Don’t need to do for test!!
SCI Clinical Manifestations: Respiratory System
- Closely correspond to level of injury
- Above level of C4 = Total loss of respiratory muscle function
- Below level of C4 = Diaphragmatic breathing → respiratory insufficiency
- Cervical and thoracic injuries
- Risk for neurogenic pulmonary edema
SCI Clinical Manifestations of the Respiratory System: Cervical and Thoracic Injuries can cause
Paralysis of abdominal and intercostal muscles → ineffective cough → risk for aspiration, atelectasis, pneumonia
*Read notes!
SCI Clinical Manifestations: Cardiovascular System
- Injury above T6 leads to dysfunction of sympathetic nervous system
- Leads to neurogenic shock:
- bradycardia
- peripheral vasodilation
- hypotension: Relative hypovolemia (because of increase in capacity of dilated veins) and reduced venous return = decreased CO.
SCI Clinical Manifestations: Urinary System
- Neurogenic Bladder
- Acute phase symptoms
- Postacute phase symptoms
SCI Clinical Manifestations of Urinary System: Neurogenic Bladder
Bladder dysfunction related to abnormal or absent bladder innervation:
- No reflex detrusor contractions (flaccid, hypotonic)
- Hyperactive reflex detrusor contractions (spastic)
- Lack of coordination between detrusor contraction and urethral relaxation (dyssynergia)
*Read notes!
SCI Clinical Manifestations of Urinary System: Acute Phase symptoms include
- Urinary retention
- Bladder atonic, overdistended, fails to empty
- Indwelling catheter (inserted to drain catheter)
SCI Clinical Manifestations of Urinary System: Postacute phase symptoms include
- Bladder may become hyperirritable
- Loss of inhibition from brain
- Reflex emptying and failure to store urine
SCI Clinical Manifestations: GI System
- Decreased GI motor activity:
- Gastric distention
- Development of paralytic ileus
- Gastric emptying may be delayed
- Excessive release of HCl may cause stress ulcers
- Dysphagia may be present
- Intraabdominal bleeding may be difficult to diagnose
*Read notes