Spinal Cord Injury (Week 2--Peacock)

Question 1

Epidemiology of spinal cord injury (SCI)

Answer 1

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)

Question 2

Three main spinal cord tracts (again)

Answer 2

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)

Question 3

Blood supply of spinal cord

Answer 3

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

Question 4

Functions of the spinal cord

Answer 4

Motor

Sensory

Autonomic: BP, bladder, sexual function

Question 5

Function of descending motor tracts

Answer 5

1) Coordination of muscular contraction to produce a purposeful movement
2) Inhibition of muscle tone

Question 6

Motor deficits caused by upper motor nerve lesion vs. lower motor nerve lesion

Answer 6

UMNL: spastic weakness (loss of descending inhibition of muscle tone)

LMNL: flaccid weakness (cauda equina injury since those are lower motor neurons!)

Question 7

Pathology of spinal cord injuries

Answer 7

Mechanism (fracture/dislocation of spine, penetrating wound (stab or bullet))

Level (50% cervical, 30% thoracolumbar, 20% conus/cauda equina)

Extent (complete, incomplete)

Question 8

3 types of fracture or dislocation of the spine

Answer 8

1) Hyperflexion (driving into wall)
2) Hyperextension (being rear-ended)
3) Axial load (diving into shallow pool)

Question 9

Clinical syndromes of complete vs. incomplete SCI

Answer 9

Complete: quadriplegia (arms and legs), paraplegia (legs)

Incomplete: Central Cord Syndrome, Brown Sequard Syndrome, Anterior Cord Syndrome

Question 10

What does thoracolumbar complete SCI cause?

Answer 10

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

Question 11

What does cervical complete SCI cause?

Answer 11

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

Question 12

What spinal cord injury level causes loss of respiration?

Answer 12

Injury to C3 or above causes loss of respiration and requires ventilator

Question 13

Level of SCI and deficit caused

Answer 13

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

Question 14

What does conus medullaris and cauda equina injury cause?

Answer 14

Remember cauda equina is peripheral nerve!

Lower extremity weakness

Patchy saddle/perineal sensory loss

Urinary retention (decreased parasymp?)

Bowel incontinence

Loss of sexual function

Question 15

How do we define the level of injury?

Answer 15

Lowest (most caudal) neurological segment with both normal motor and sensory function

Question 16

Evaluating motor levels

Answer 16

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

Question 17

Sensory (dermatomal) levels

Answer 17

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

Question 18

Bladder in UMNL vs. LMNL

Answer 18

Upper motor neuron lesion: small, spastic, irritable bladder

Lower motor neuron lesion: large, flaccid, inert bladder (overflow incontinence)

Question 19

Central Cord Syndrome

Answer 19

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)

Question 20

Brown Sequard Syndrome (hemisection)

Answer 20

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)

Question 21

Anterior Cord Syndrome

Answer 21

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

Question 22

ABCs of acute management of SCI

Answer 22

1) Airway, breathing, circulation
2) Anchor neck (then extract), bladder (catheterize), compassion (denial, anger, depression, acceptance)

Question 23

Late problems and management of SCI

Answer 23

Loss of bladder control

Dysautonomia

Spasticity

Pressure sores

Sexual dysfunction

Question 24

Where are sacral bladder reflexes controlled?

Answer 24

Higher centers (pons and midbrain)

Bladder fullness is experienced in insular cortex

Social appropriateness of timing of micturition determined by prefrontal and cingulate cortex

Question 25

Autonomic dysreflexia (dysautonomia)

Answer 25

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

Question 26

Pressure ulcer

Answer 26

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