Neuroscience/Objectives/Lecture 16

From PhysioWiki

Spinal cord injury

Describe a typical spinal cord injury (SCI) in terms of the cause of injury, characteristics of the patient, and expected lifespan after injury.

Most common causes of SCI:

• Motor vehicle accident (40%)
• Acts of violence (gunshot wounds prevail)

SCI patient characteristics:

• 16-30 years old (53%)
• Caucasian (80%)
• African Americans and Hispanics disproportionately affected

Expected life expectancy following SCI:

• Pre-WWII: 2 years
• Post-WWII: 30 years
  • Primary cause of death is disease of pulmonary system (commonly pnemonia)

Understand the difference between complete and incomplete SCI.

Complete SCI

Results in a complete loss of motor and sensory function caudal to the lesion. Implies that S4 and S5 are nonfunctional.

Incomplete SCI

Results in partial loss of motor and/or sensory function caudal to lesion. Implies that spinal levels S4 and S5 are at least partially intact.

Learn the effect of differences in segmental level on the functional consequences (symptoms) of complete SCI and list the expected findings detected by a clinical neurological examination.

A brief note on nomenclature:
When identifying the level of an SCI, the last functioning spinal segment is used. For example, in a C4 lesion, spinal segments C1-C4 (including C4) are functional. Likewise, in a T6 lesion, all segments from C1 up to and including T6 are functional.

Distinguish between the following: Brown-Sequard syndrome, central cord syndrome, anterior cord syndrome.

Brown-Sequard syndrome

Hemisection of the spinal cord resulting in asymmetric weakness of the musculoskeletal system and hypalgesia. Characterized by:

• ipsilateral flaccid paralysis at level of lesion
• ipsilateral loss of all sensory modalities at level of lesion
• contralateral loss of pain and temperature below lesion
• ipsilateral loss of position sense and vibration below lesion
• ipsilateral motor loss below level of lesion

BSS patients have greatest prognosis for return of function and potential for ambulation. Whether the major site of weakenss is the upper or lower limbs is the major predictor of future function.

Central cord syndrome

Most common of the incomplete SCI syndromes, and found almost exclusively in cervical SCIs. Characterized by:

• motor weakness in upper extremeties (more so than in the lower extremeties)
• partial loss of sensation below lesion (lose part of dorsal columns and anterolateral system)

CCS occurs often in older patients following hyperextension injury; favorable prognosis for patients under 50. Lower extremeties recover first and to the largest extent. Proximal upper extremity function returns before hand function.

Anterior cord syndrome

Involves a lesion affecting the anterior two-thirds of the spinal cord (caused by retropulsed disc or bone fragments, anterior spinal artery lesion), with preservation of the dorsal columns. Characterized by:

• loss of motor function (with poor prognosis for recovery)
• retention of deep pressure and proprioceptive sensation (still have dorsal columns)

ACS has the worst prognosis of all the cord syndromes.

Explain how injury at the conus medullaris/cauda equina is likely to produce different types of symptoms and may not be considered an SCI.

Conus medullaris/cauda equina injuries are usually accompanied by lower motor neuron deficit, leading to impairment of bowels, bladder, and/or may affect the strength of the lower limbs.

A cauda equina injury is not considered a spinal cord injury since the spinal cord proper ended at the level of the L1 vertebra. Instead, cauda equina injuries are considered injuries to the peripheral nervous system.