spinal anatomy and injury Flashcards
What is a dermatome
area of skin supplied by a single spinal nerve
What is a myotome
Group of muscles that a single spinal nerve innervates
Who do spinal cord injuries more commonly affect
males
20-30 year olds
What are the common causes of spinal cord injuries
Falls
RTA - road traffic injuries
Sport
What are the symptoms of a complete spinal cord injury
No motor or sensory function distal to the lesion
Loss of anal tone
No sensation at the sacrum
no chance of recovery
What are the symptoms of incomplete spinal cord injury
Some functions still present distal to the lesion and usually a more favourable prognosis compared to complete spinal cord injuries
Describe the asia classification
A-E classification of spinal cord injuries
A - complete spinal cord injuries with no function preserved distal to the lesion
B - incomplete spinal cord injury - sensory function preserved distal to the lesion at the sacrum (motor not preserved)
C - incomplete spinal cord injury - motor function preserved distal to the lesion - muscles have grade less than 3
D incomplete spinal cord injury - motor function preserved distal to the lesion with the majority of the muscles having a grade higher than 3
E - incomplete spinal cord injury with normal motor and sensory function distal to the lesion
What level of lesion causes tetraplegia/quadriplegia
Above the innervation to the limbs - results in paralysis of all 4 limbs
What level of lesion causes paraplegia
Below the innervation of the arms - causes paralysis of the lower limbs
What is tetraplegia (quadraplegia)
Partial or total loss of all 4 limbs and the trunk
Loss of motor and sensory function in the cervical segments of the spinal cord
Why can a cervical fracture cause respiratory failure
If the phrenic nerve becomes damaged - (C3-5)
What is spasticity
Increased muscle tone
Upper motor neuron lesion
Spinal cord and above (CNS)
Injuries above L1 - termination of spinal cord below that which is mainly just peripheral nerves
What are the 3 partial cord syndromes
central cord syndrome
anterior cord syndrome
brown- Sequard syndrome
What is paraplegia
Partial or total loss of lower limbs
Impaired sensory and motor function in the thoracic, lumbar or sacral legions
Arm function is spared
Who does central cord syndrome more commonly affect
older patients
What tracts are more involved in central cord injuries and what is the result of that
centrally cervical tracts are more involved and since the lower limb tracts are more peripheral, there is more weakness in the arms compared to the legs
how does central cord syndrome present
Hyperextension injury
weakness of arms more than legs
Perianal sensation and lower extremity power is preserved
What causes anterior cord syndrome
Hyper flexion injury that causes an anterior compression fracture
how does anterior cord syndrome present
Damaged anterior spinal artery
Fine touch and proprioception preserved
Profound weakness due to lateral corticospinal tract damage
Spinothalamic tract damage so loss of pain and temperature sensation
What causes brown-sequard syndrome
Hemi-section of the spinal cord
How does brown-Sequard syndrome present
Loss of proprioception and fine discrimination on the same side as the lesion due to the dorsal column crossing over at the hindbrain region above the lesion
Paralysis on same side as lesion due to corticospinal tract crossing over at the hindbrain above the lesion
Pain and temperature loss at the opposite side below the lesion - due to the spinothalamic tract crossing over at the level of the lesion at the spinal cord
What is spinal shock
Transient depression of cord function below the level of the injury
causes flaccid paralysis
Areflexia - absence of reflexes
Lasts from hours to days after the injury
What is neurogenic shock
Loss of the sympathetic tone
Injuries have to be above T6 because the sympathetic outflow is damaged
The loss of sympathetic tone causes hypotension, bradycardia and hypothermia
What are the investigations done for spinal injury
X rays
CT scanning
MRI - if there is neurological deficit or in children
What is the preferred surgical fix for stabilising the spine
screws that are passed into the pedicle
Which unit are people with spinal injuries admitted to
Spinal cord injury unit
