Spinal Cord Injury (Week 2--Peacock) Flashcards
Epidemiology of spinal cord injury (SCI)
Stats: 10,000 per year in USA; 1,000 per year in CA; 2 per day in Southern CA; 250,000 living with SCI in USA
Age: 16-30, >60
Gender: 80% male
Causes: 43% MVA, 27% falls, 15% violence, 7% sports, 8% other (obstetrics, AAA surgery)
Three main spinal cord tracts (again)
1) Lateral corticospinal tract (descending; motor; already crossed)
2) Dorsal columns (ascending; light touch and position sense; still needs to cross)
3) Anterolateral tract (ascending; pain and temperature; already crossed)
Blood supply of spinal cord
Longitudinal: single anterior spinal artery (comes off vertebral artery) for anterior 2/3 of cord; 2 posterior spinal arteries for posterior 1/3 of cord
Segmental: radicular arteries (arteria radicularis magna) from T9-L2
Functions of the spinal cord
Motor
Sensory
Autonomic: BP, bladder, sexual function
Function of descending motor tracts
1) Coordination of muscular contraction to produce a purposeful movement
2) Inhibition of muscle tone
Motor deficits caused by upper motor nerve lesion vs. lower motor nerve lesion
UMNL: spastic weakness (loss of descending inhibition of muscle tone)
LMNL: flaccid weakness (cauda equina injury since those are lower motor neurons!)
Pathology of spinal cord injuries
Mechanism (fracture/dislocation of spine, penetrating wound (stab or bullet))
Level (50% cervical, 30% thoracolumbar, 20% conus/cauda equina)
Extent (complete, incomplete)
3 types of fracture or dislocation of the spine
1) Hyperflexion (driving into wall)
2) Hyperextension (being rear-ended)
3) Axial load (diving into shallow pool)
Clinical syndromes of complete vs. incomplete SCI
Complete: quadriplegia (arms and legs), paraplegia (legs)
Incomplete: Central Cord Syndrome, Brown Sequard Syndrome, Anterior Cord Syndrome
What does thoracolumbar complete SCI cause?
Paraplegia
Paralysis of lower limbs
Loss of sensation below lesion (umbilicus is at T10 for sensation)
Loss of bowel and bladder control
Loss of sexual function
What does cervical complete SCI cause?
Quadriplegia
Motor and sensory loss in upper limbs dependent on level of lesion
Paralysis of whole trunk and legs
Loss of sensation below lesion
Loss of bowel and bladder function
Loss of sexual function
What spinal cord injury level causes loss of respiration?
Injury to C3 or above causes loss of respiration and requires ventilator
Level of SCI and deficit caused
If last intact segment is:
C4: respiration intact but complete paralysis and sensory loss below level of lesion
C5: abduct shoulders, flex elbows
C6: extend wrist
C7: extend elbow
C8: flex fingers
T1: fine finger function
What does conus medullaris and cauda equina injury cause?
Remember cauda equina is peripheral nerve!
Lower extremity weakness
Patchy saddle/perineal sensory loss
Urinary retention (decreased parasymp?)
Bowel incontinence
Loss of sexual function
How do we define the level of injury?
Lowest (most caudal) neurological segment with both normal motor and sensory function
Evaluating motor levels
C5: elbow flexors (and shoulder abductors)
C6: wrist extensors (and elbow flexors)
C7: elbow extensors
C8: finger flexors
T1: finger abductors
L2: hip flexors
L3: knee extensors
L4: ankle dorsiflexors
L5: long toe extensors
S1: ankle plantarflexors
Sensory (dermatomal) levels
C5: shoulder
C6: lateral arm, thumb, index finger
C7: middle finger
C8: ring, little finger (medial arm?)
T1: medial arm
T4: nipple
T10: umbilicus
L2: anteromedial thigh
L3: anteromedial knee
L4: anteromedial leg (calf)
L5: lateral leg (calf)
S1: lateral heel
S2: back of thigh
S3,4,5: peri-anal
Bladder in UMNL vs. LMNL
Upper motor neuron lesion: small, spastic, irritable bladder
Lower motor neuron lesion: large, flaccid, inert bladder (overflow incontinence)
Central Cord Syndrome
Elderly patient with cervical spinal stenosis falls and gets hyperextension injury with compression of central cord
Central cord is vascular watershed zone
Upper limb fibers are more central and most damaged
Lower limb fibers are more peripheral in dorsal columns, SCT and anterolateral tracts and thus are more protected
Anterior horn cells are vulnerable
Clinical features: severe weakness of upper limbs and lesser weakness of legs, variable sensory loss, urinary retention, gradual improvement (lower limbs first then bladder then upper limbs and fingers last)
Brown Sequard Syndrome (hemisection)
Stab wound severs and disconnects right half of cord at T10
Clinical features: right-sided motor loss, right-sided dorsal column sensation loss, left-sided pain and temperature loss two segments lower (bc axon travels up 2 levels then crosses)
Anterior Cord Syndrome
Fracture dislocation with fragment compressing anterior spinal artery causes infarction of 2/3 of anterior cord
Clinical features: complete paralysis and loss of pain below lesion, preservation of dorsal column sensation, loss of bowel, bladder and sexual function
ABCs of acute management of SCI
1) Airway, breathing, circulation
2) Anchor neck (then extract), bladder (catheterize), compassion (denial, anger, depression, acceptance)
Late problems and management of SCI
Loss of bladder control
Dysautonomia
Spasticity
Pressure sores
Sexual dysfunction
Where are sacral bladder reflexes controlled?
Higher centers (pons and midbrain)
Bladder fullness is experienced in insular cortex
Social appropriateness of timing of micturition determined by prefrontal and cingulate cortex
Autonomic dysreflexia (dysautonomia)
Affects patients if lesion above T6
Loss of descending inhibitory autonomic tract
Noxious stimulus (bladder infection, bowel obstruction, skin sore, extremity pain) causes this 2-3 months out from SCI
Excessive sympathetic output causes vasoconstriction and arterial hypertension
Patient develops headache, sweating, flushing, rise in BP, +/- bradycardia (vagus attempts compensation by inducing bradycardia)
Complications: subarachnoid hemorrhage, intracerebral hemorrhage, MI, death
Treatment: recognize early, remove cause, sit patient up, anti-hypertensive meds
Pressure ulcer
Due to unrelieved pressure over bony prominence
Starts as area of reddened skin, blisters, forms ulcer then crater
Prevent by turning patient frequently and avoiding prolonged pressure in wheelchairs
