Spinal Injury

Question 1

What is spinal shock?

Answer 1

Transient depression of neurological activity below the level of an acute spinal cord injury.

Question 2

What are the clinical features of spinal shock?

Answer 2

Loss of nociception (pain)
Loss of proprioception
Sympathetic dysfunction (bladder and bowel)
Loss of Thermoregulation.

Question 3

Name the stages of spinal shock and their time periods?

Answer 3

Day 0-1: Arreflexia and flaccidity
1-3 days: Initial reflex return
1-4 weeks: Initial hyperreflexia
1-12 months: Hyperreflexa and spasticity.

Question 4

Describe the first phase of spinal shock?

Answer 4

Arreflexia and flaccidity - Loss of descending facilitation.
- Neurons involved in reflex arcs lose their basal level of excitatory stimulation they get from the brain.

Question 5

Describe the 2nd phase of spinal shock?

Answer 5

Initial reflexes return - denervation supersensitivity.
- Relfexes retuen due to hypersenstiivty of reflex muscles following denervation. More receptors for neurotransmitters are expressed and muscles are therefore easier to stimulate.

Question 6

Describe the third phase of spinal shock?

Answer 6

Initial hyperreflexia - axon supported synapse growth.

• Interneurons and lower motor neurons below transection begin sprouting attempting to reestablish synapses.
• First synapses to form are from shorter axons e.g. interneurons.

Question 7

Describe phase 4 of spinal shock?

Answer 7

Hyperreflexia and spasticity - soma-supported synapse growth.
- This takes longer as have to take proteins and growth factors from soma to end of axon.

Question 8

What is the first reflex to return in spinal shock?

Answer 8

Plantar reflex

Question 9

What reflex indicates the end of spinal shock? How would you test for it?

Answer 9

Bulbocavernosus Reflex.

Squeeze glans or clitoris, or pull on catheter and monitor anal sphincter contraction.

Question 10

What is neurogenic shock?

Answer 10

A type of disruptive shock due to sudden loss of sympathetic control.

Question 11

Describe the features of neurogenic shock?

Answer 11

Hypotension and Bradycardia due to loss of vascular tone and reduced venous return.
Hypothermia due to damage to thermoregulation and loss of swearing below the level of injury.

Question 12

When would neurogenic shock occur?

Answer 12

With injury at T6 or above.

Question 13

Define an upper motor neuron lesion?

Answer 13

In the neural pathway above the anterior horn cell of the cord or the motor nuclei of the cranial nerves.

Question 14

Define a lower motor neuron lesion?

Answer 14

A lesion affecting nerves after the anterior horn cell or cranial nerve nuclei.

Question 15

Describe features of an upper motor neuron lesion?

Answer 15

No muscle wasting 
No fasiculations 
Spastic tone 
Weakness/paralysis due to a-motor neurons not being recruited. 
Hyperreflexic 
Positive babinski sign.

Question 16

Describe features of a lower motor neuron lesion?

Answer 16

Muscle wasting 
Fasiculations
Flaccid tone 
Weakness/paralysis 
Hyporeflexic or areflexic

Question 17

Describe the return of somatic reflexes after spinal cord injury?

Answer 17

Flexor activity returns first
Extensor reflexes return about 6 months after but tend to be exaggerated leading to spastic paralysis.
Then get extensor spasms and hyperreflexia.

Question 18

Describe how respiration could be affected in spinal cord injury?

Answer 18

Injury at C5 or above can affect the diaphragm and my have little resp control and need artificial ventilation.
Intercostal muscles are supplied by C6-7, so a lesion between C5-C7 means breathing can occur but without accessory muscles, so may have difficulty coughing, clearing secretions.

Question 19

Describe limb paralysis at the following spinal levels.

C1-4?
C5?
C7/T1?
T1-8?
Lumbosacral?

Answer 19

Quadriplegia

Control of shoulder/biceps but no control of hand and wrist.

Most upper limb control, may still affect dexterity.

Paraplegia - poor control of trunk

Decreased control of hip flexors and legs.

Question 20

Describe bladder control in injuries above T12. How would this be controlled medically?

Answer 20

Above T12 - reflex bladder
Afferent signals cant reach brain so no awareness of filling. No descending control of external sphincter so it is relaxed.
Spinal reflex is intact so get sensory > sacral > pelvic signalling. Detrusor can control in response to stretch and automatically empties as it fills.

Intermittent or suprapubic catheters.

Question 21

Describe bladder control in injuries below T12.

Answer 21

Parasympathetic outflow is damaged ans detrusor is paralysed. Reflex cant function. Bladder fills and when abnormally distended get overflow incontinence.

Question 22

Describe bladder function in the spinal shock phase?

Answer 22

Bladder fills and just trickles overflow.

Question 23

Describe bowel function in UMNL vs. LMNL.

Answer 23

UMNL: Can fill and empty, but not at an appropriate time.

LMNL: Fills and overflows. Must use manual evacuation.

Question 24

Describe pregnancy in spinal cord injury?

Answer 24

Females can have hormone controlled conception and vaginal delivery.

Question 25

Describe sexual function in males in spinal cord injury?

Answer 25

May need viagra and elector-ejaculation.

Can sometimes get an errection via the spinal reflex.

Question 26

Describe sexual function in males in spinal cord injury?

Answer 26

May need viagra and elector-ejaculation.

Can sometimes get an erection via the spinal reflex.

Question 27

Give examples of incomplete spinal cord injuries?

Answer 27

Central cord syndrome
Brown-sequard syndrome
Cauda Equina syndrome

Question 28

Why does central cord syndrome normally occur?

Answer 28

In older patients due to low velocity injuries such as hyperextension.
They may have a narrow central canal due to osteophytes or hardening of the ligamentum flavum.

Question 29

Describe clinical features of central cord syndrome?

Answer 29

Intact fine touch
Strong legs
Altered temperature
Weak upper limbs

Question 30

What is brown-sequard syndrome?

Answer 30

Hemi-section of the cord usually due to penetrating injuries e.g. stab wound.

Question 31

Describe clinical features of brown-sequard syndrome?

Answer 31

Paralysis (corticospinal)
Loss of proprioception and fine discrimination (DCML)
Contralateral pain and temp loss (spinothalamic)

Question 32

Why would cauda equina syndrome occur?

Answer 32

Disc protrusion or bony compression in the lumbar or sacral region.

Question 33

Describe clinical features of cauda equina?

Answer 33

Back pain
Saddle parathesia
Leg numbness and weakness
Bladder and bowel dysfunction.