PHTY209 Lecture Notes - Lecture 7: Vasoconstriction, Spinal Shock, Sciatica
Spinal cord injury
• Describe the causes of spinal cord injury, including examples of traumatic and
pathological;
o Traumatic
• MVA, MBA, sporting, falls, violence
• Primary/immediate damage
• MOI
▪ Spinal contusion: bleeding within the vertebral canal or in the
meningeal layers
▪ Spinal laceration: tearing of the spinal cord neural tissue by bone
fragments, or foreign body
▪ Spinal compression: spinal cord is squeezed or squashed within the
vertebral canal
▪ Spinal transection: complete severing of the cord
▪ Combination of all the above
o Pathological
• Infections
• Degenerative
• Tumours
o Congenital
• Spina bifida
o Effects of lesions to SC
• A lesion in the spinal region may interfere with the following
▪ Segmental function
• Causes segmental signs at that level (likewise if a focal lesion
affects the dorsal or ventral roots)
• At the level of the lesion sensory motor and/or reflexes change
▪ Vertical tract function
• Results in loss of communication to and/or from the spinal levels
below the lesion
• All signs of damage occur below the level of the lesion
• Ascending sensory tract dysfunction
• Autonomic tract signs (regulation of BP, sweating,
bowel/bladder)
• Descending motor tract signs (e.g. paralysis, spasticity,
hypertonia, hyperreflexia, or hypo if motor neuron
involvement)
• Both segmental and vertical tract function
o Differentiating spinal region from peripheral region lesions
• Peripheral region nerves produce deficits in the distribution of a peripheral
nerve
▪ Cause
• Altered or lost sensation in a peripheral nerve distribution
• Decrease or loss of muscle power in a peripheral nerve
distribution
• No vertical tract signs
• Decreased or lost phasic stretch reflex
• Spinal region segmental signs occur when nerve roots and/or spinal nerves
are compromised
▪ Signs include
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• Altered or lost sensation in a dermatome
• Decreased or lost muscle power in a myotome
• Decreased or lost phasic stretch reflex
• Altered or lost sensation below the level of the lesion
• Altered or lost descending control of BP, pelvic viscera and
thermoregulation
• Motor tract signs including decrease or loss of muscle power,
spasticity, muscle hypertonia and if the lateral corticospinal tract
is involved, positive Babinski's sign and clonus
o SCI classification
• Whether the injury is complete or incomplete
▪ Complete
• Lack of sensory and motor function in the lowest sacral segment =
total block motor/sensory information
▪ Incomplete
• Preservation of sensory and/or motor function in the lowest
sacral segment = partial block motor/sensory information
• Neurological level of injury
▪ Most caudal level with normal sensory and motor function bilaterally
▪ Tetraplegia/quadriplegia
▪ Paraplegia
• Define the terms
o Paraplegia
• Injury of thoracic and lumber cord results in paraplegia i.e. paralysis of lower
limbs
• Next most common level of injury T12/L1
o Quadriplegia
• Injury of the cervical cord results in quadriplegia i.e. paralysis of the upper and
lower limbs
• Cervical cord (C4-5) most commonly damaged
• Describe how spinal cord injuries may be classified including The American Spinal Cord
Injury Association (ASIA) classification system
o Assessed supine
o 10 key myotomes and 28 dermatomes (tested for light tough and pin prick
sensation)
o Allows examiner to determine the motor, sensory and neurological level of injury
and degree of completeness
o Impairment scale
• A
▪ Complete
▪ No sensory or motor function is preserved in the sacral segments S4-5
• B
▪ Sensory incomplete
▪ Sensory but not motor function is preserved below the neurological
level and includes the sacral segments S4-5 (light tough or pin prick at
S4-5 or deep anal pressure)
▪ And no motor function is preserved more than three levels below the
motor level on either side of body
• C
▪ Motor incomplete
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