Neurologic functions

• Spinal Cord Injury (SCI)

  • Caused by trauma or damage to the spinal cord
  • Result in either a temporary or permanent alteration in the function of the spinal cord
  • Young adult men between ages 16 and 30 years have the greatest risk
  • 81 % are male
• Etiology

  Most common causes:

  • motor vehicle collisions (42%)
  • falls (27%)
  • violence (15%)
  • sports injuries (7%)
  • other miscellaneous causes (8%)
• Pathophysiology

  Extent of the neurologic damage results from

  • primary injury (actual physical disruption of axons) and
  • secondary injury (ischemia, hypoxia, hemorrhage, and edema)
• Primary Injuries

  • Tough layers of dura is rarely torn or transected by direct trauma
  • Can be due to cord compression by bone displacement, interruption of blood supply to the cord, or traction resulting from pulling on the cord
  • Penetrating trauma, e.g., gunshot and stab wounds result in tearing and transection
  • Refers to the initial mechanical disruption of axons as a result of stretch or laceration
• Secondary Injury

  • Refers to the ongoing, progressive damage that occurs after the primary injury
  • Apoptosis (cell death) occurs may continue for weeks or months after the initial injury
  • Complete cord damage in severe trauma =related to autodestruction of the cord
• Hemorrhagic areas in the center of the spinal cord appear within 1 hour

  By 4 hours: infarction in the gray matter

  By 24 hours or less, permanent damage may occur because of the development of edema
• • Edema secondary to the inflammatory response is particularly harmful because of lack of space for tissue expansion
  • 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
  • Vasoactive substances - cause vasospasms and hypoxia =necrosis
  • Compression of the spinal cord
  • Edema - extends above and below the injury =increasing the ischemic damage
• The extent of the injury and prognosis for recovery are most accurately determined at least 72 hours or more
• Traumatic injury

  • Motor vehicle crashes
  • Falls
  • Acts of violence
  • Sports injuries
• Non-traumatic injury

  • Case of cancer
  • Infection
  • Intervertebral disc disease
  • Vertebral injury
  • Spinal cord vascular disease
  • Osteoporosis/arthritis
• Spinal Shock - is a temporary neurologic syndrome that is characterized by decreased or loss reflexes, loss of sensation, and flaccid paralysis below the level of injury
• Hyperreflexia - exaggerated deep tendon reflexes
• Spasticity - is a motor disorder caused by upper motor neuron lesions (UMN) resulting from brain or spinal cord injury.
• Clonus - rapid repetitive contraction of muscle following a sudden stretch
• Hemiplegia - weakness on one side of the body due to damage to the opposite cerebral hemisphere
• Paraplegia - partial or complete loss of function in the lower limbs
• Quadriplegia - partial or complete loss of movement and feeling in all four limbs
• Dysesthesias - abnormal sensations such as tingling, burning, itching, numbness, or pain
• Paresthesias - abnormal sensory perceptions without any apparent physical cause
• Aphasia - language impairment, usually caused by stroke or head trauma
• Apraxia - difficulty with purposeful movements despite normal strength and coordination
• Dysarthria - speech difficulties due to problems with articulation, phonation, respiration, or prosody
• Astereognosis - impaired ability to recognize objects through touch
• Allodynia - sensation that normally does not cause pain becomes painful
• Hyperpathia - exaggerated response to painful stimuli
• Anosmia - lack of sense of smell
• Neurogenic Shock - is due to the loss of vasomotor tone caused by injury

  • Characterized by hypotension and bradycardia
  • Loss of sympathetic nervous system innervation causes peripheral vasodilation, venous pooling, and a decreased cardiac output
  • Associated with a cervical or high thoracic injury (T6 or higher)
• Classification of Spinal Cord Injury

  • Mechanism of injury
  • Level of injury
  • Degree of injury
• Mechanisms of Injury

  Major mechanisms of injury:

  • flexion
  • hyperextension
  • flexion-rotation: the most unstable because the ligamentous structures that stabilize the spine are torn; most often implicated in severe neurologic deficits
  • extension-rotation
  • compression
• Skeletal level of injury

  The vertebral level where there is the most damage to vertebral bones and ligaments
• Neurologic level

  The lowest segment of the spinal cord with normal sensory and motor function on both sides of the body
• Levels of injury

  • Cervical
  • Thoracic
  • Lumbar
  • Sacral
• Cervical and lumbar injuries


  • Most common because these levels are associated with the greatest flexibility and movement
• Tetraplegia (formerly termed quadriplegia)


  Paralysis of all four extremities when the cervical cord is involved
• Paraplegia


  Paralysis and loss of sensation in the legs when the thoracic, lumbar, or sacral spinal cord is damaged
• When the damage is low in the cervical cord, the arms are rarely completely paralyzed
• • C4 Injury Tetraplegia,

  results in complete paralysis below the neck

  • C6 Injury

  Results in partial paralysis of hands and arms as well as lower body

  • T6 Injury

  Paraplegia, results in paralysis below the chest

  • L1 Injury

  Paraplegia, results in paralysis below the waist
• Degree of Injury - May be either complete or incomplete (partial)
• Complete cord involvement - Results in total loss of sensory and motor function below the level of injury
• Incomplete cord involvement - Results in a mixed loss of voluntary motor activity and sensation and leaves some tracts intact