spinal cord injury anatomy, pathophysiology, and examination

what are causes of spinal cord injury?

trauma

spinal abscess

spinal tumor

spinal infarct or AVM

multiple sclerosis

spinal stenosis

transverse myelitis

what are traumatic causes of SCi?

car accidents

falls

violence

sports

what causes spinal stenosis and who/where is it most common?

older adults

minor fall or trauma damages SC

cervical or lumbar spine most common

what is transverse myelitis? what can cause it?

inflammation of spinal cord

viral infections and IV drug use

what are the demographics for SCIs?

80% male vs 20% female

age: bimodal (15-29 and >65)

what is the order of commonality for SCIs?

incomplete tetraplegia

incomplete paraplegia

complete paraplegia

complete tetraplegia

what is the impact of SCIs?

lengthy hospitalizations (decreasing)

medical complications

extensive follow up

recurrent complications

financial

decreased life expectancy

what is the difference between acute care and inpatient rehab stay for SCIs?

acute care: 11 days

inpatient rehab: 35 days

vertebral segment is the ______

actual bone

what is a spinal cord segment?

section/segment of the spinal cord where paired nerve roots exit the spinal cord proper

how are spinal cord segmental levels defined?

by their corresponding nerve roots (dorsal and ventral)

a spinal cord segment is a spinal cord section that gives rise to what?

one nerve root

how many spinal cord segments are there?

8 cervical

12 thoracic

5 lumbar

5 sacral

1 coccygeal

what are the spinal cord segments with their related vertebral levels?

cervical:

thoracic:

lumbar:

sacral:

cervical: C1-C7

thoracic: C7-T11

lumbar: T11-L1

sacral: L1-L2

true or false: spinal cord segments geographically correspond with the vertebral segment

false

where does spinal cord proper end?

L1-L2

what type of lesion is an SCI? conus medullaris injury? cauda equina? nerve root injuries? peripheral nerves?

SCI = UMN

conus medullaris = UMN/LMN

cauda equina = LMN

nerve root = LMN

peripheral nerve = LMN

what are the rules of an SCI?

the level of the spinal cord injury (naming) = the lowest level where both sensory and motor function are intact

the spinal cord segments are not the same as the vertebral body segments

an SCI is a UMN injury except conus medullaris and cauda equina presentations

what is involved with diagnosis of a UMN SCI?

UMN signs are present if the white matter tract/pathways are damaged (spinal cord proper)

information between brain and spinal cord is disrupted leading to hyperreflexia, spasticity, clonus, upgoing babinski

what is involved with diagnosis of a LMN SCI?

LMN signs if only the motor neurons are damaged at the nerve root of the segmental level of the injury

leading to areflexia, flaccid paralysis, muscle atrophy

what is the primary injury involved with SCI?

vertebral fracture, subluxation or dislocation as a result of trauma impinging the spinal cord (compression)

white matter axons directly lesioned and often begins in gray matter, blood vessels shear and rupture

what happens with trauma to the spinal cord?

hemorrhage

tissue laceration

edema

necrosis

what is involved with secondary injury?

ischemia, inflammation, apoptosis

toxic environment is created by the initial injury and the area of damage is increased

the central area supplied only by ASA is a predominantly _____ area

motor

what is involved with ischemia and secondary injury?

rupture/compression of blood vessels

vasospasm, thromboses, edema, vasoconstriction

what is involved with inflammation and secondary injury?

expands area of necrosis

what is involved with ion derangement and secondary injury?

sodium/potassium --> excitotoxicity

apoptosis --> particulary oligodendrocytes with demyelination and axon degeneration

what is spinal shock?

depression of neural activity in the spinal cord

reflexes below the injury are absent or very weak (hyporeflexic) --> diaschisis or temporary

progression from hyporeflexia to hyperreflexia (look for return of DTR or babinski)

how long does it take for return of uninjured function with spinal shock?

days to months