Spinal Injuries (Sources: OH's, Revision notes)

Question 1

What are the commonest mechanisms leading to SCI?

Answer 1

MVA - cars, motor bikes, bicycles
Falls - domestic and industrial
Sports-related
Diving

Question 2

Briefly, describe the anatomy of the spinal cord

Answer 2

Extends from the foramen magnum to L1-L2 level
The lower end is called the conus medullar is, from which arises the film terminale, a filament of connective tissue
The caudal equina is the bundle of nerves from the limbo-sacral region that continue below the spinal cord.
The spinal nerves run caudally within the spinal column until reaching the corresponding spinal levels, exiting through the spinal foramen

Question 3

Where does the sympathetic nerve supply originate?

Answer 3

Originates from the intermediolateral column of segments T1-L2

Question 4

Where does the parasympathetic outflow originate?

Answer 4

S2-S4 and supplies pelvic viscera

Question 5

What are the 2 phases of a SCI?

Answer 5

Primary Injury and secondary injury

Question 6

Describe the primary phase of SCI

Answer 6

Direct mechanical injury may produce:
 - focal compression
  -laceration
  - traction injury to the cord
  -direct transection is unusual
Ischaemic injury may result from interference to the spinal arterial supply

Question 7

Describe the secondary phase of SCI

Answer 7

Local hypo perfusion and ischaemia extends progressively from the site of injury in both direction, over hours
There is loss of spinal cord auto regulation
Apart form ischaemia, other mechanisms contributing to secondary damage include release of free radicals, reactive oxygen species, eicosanoids, calcium, proteases, phospholipase and excitotoxic neurotransmitters e.g. glutamate
Petechial haemorrhage begins in the grey matter and progress over hours, potentially producing significant cord haemorrhage
There is oedema and neuronal necrosis
In the white matter vasogenic oedema, axonal degeneration and demyelination follow

Question 8

What are the potential complications that can arise from C-spine collars?

Answer 8

Pressure ulcers
Difficulties with airway and intubation
Potential venous obstruction
Less options for central venous access
Higher risk of VTE
Higher risk of respiratory infections due to restricted physic, gastrostasis and inability to provide optimal oral care

Question 9

What are the issues that arise in the acute phase following a SCI?

Answer 9

Need for intubation
Intubation may cause further SC injury
Hypotension
Bradycardia
Difficult to assess neurology if patients are I+V
Pressure area care
Hypothermia
Urinary retention
Gastroparesis

Question 10

What are the possible indications for I+V in SCI patients?

Answer 10

Paralysis of respiratory muscles below level of injury
Increased secretions and bronchospasm from loss of sympathetic innervation
Lower respiratory tract infection
Requirement for general anaesthesia for surgery

Question 11

Why does hypotension occur in SCI patients?

Answer 11

Loss of vasomotor tone below NLOI
Bradycardia if NLOI is above T1
Concurrent injury resulting in haemorrhage

Question 12

How is hypotension in SCI patients managed?

Answer 12

Must exclude other forms of shock esp haemorrhage
Give fluids initially
Have a low threshold for noradrenaline
Consider targeting MAP 85 to maintain SC perfusion

Question 13

Why do patients with SCI become bradycardia and how is it managed?

Answer 13

Low of cardiac sympathetic innervation

May require anticholinergics (e.g. atropine), chronotropics (e.g. isoprenaline) or pacing

Question 14

Why do patients with SCI get gastroparesis and how can it be treated?

Answer 14

Loss of gastrointestinal sympathetic innervation

Managed with an NGT

Question 15

What is the definition of tetraplegia?

Answer 15

Motor and/or sensory deficits affecting both upper and lower limbs, due to cervical SCI

Question 16

What is the definition of paraplegia?

Answer 16

Motor and/or sensory deficits affecting only the lower limbs due to SCI below the cervical region

Question 17

What is the neurological level of injury?

Answer 17

The most caudal cord segment with normal motor and sensory function bilaterally

Question 18

What is a complete SCI?

Answer 18

Absence of both motor and sensory function in the lowest sacral segments (i.e. no anal tone an no sensation)

Question 19

What is the zone of partial preservation?

Answer 19

Only used in describing complete SCI

Refers to the spinal segments that have any motor or sensory function below the NLOI

Question 20

What is spinal shock?

Answer 20

The period of flaccid paresis and areflexia following a SCI

Lasting from 48 hours to weeks, ending with return of relaxes such as the bulbocavernosus reflex

Question 21

What is neurogenic shock?

Answer 21

A form of distributive shock following SCI due to loss of sympathetic tone in peripheral vasculature

Question 22

What are the possible signs of SCI in an unconscious/uncooperative patient?

Answer 22

Response to pain above a suspected level but not below
Flaccid arreflexia 
Elbow flexion with the inability to extend suggestive of cervical SCI
Paradoxical pattern of breathing
Inappropriate vasodilatation
Unexplained bradycardia or hypotension
Priapism
Loss of anal tone and reflexes

Question 23

What instrument tool should be used to diagnose and classify SCIs?

Answer 23

The American Spinal Injury Association (ASIA) impairment scale
Involves a bilateral sensory and motor exam, DRE, and determines NLOI and completeness

Question 24

What is central cord syndrome?

Answer 24

Weakness and sensory loss, greater in the arms than the legs
Typically follows a hyperextension injury with pre-existing canal stenosis, such as an elderly person falling on their chin
Ischaemia or haematoma in the central cord affects the cervical segments more due to the pattern of lamination of the corticospinal and spinothalamic tracts

Question 25

Describe anterior cord syndrome

Answer 25

Loss of motor function and pain and temperature sensation below NLOI with preservation of fine touch and proprioception Typically occurs following interruption of the blood supply to the anterior spinal cord

Question 26

Describe Brown-Sequard syndrome

Answer 26

Ipsilateral loss of motor, proprioception and fine touch, with contralateral loss of pain and temperature below the NLOI - usually follows a penetrating injury damaging only one half of the SC

Question 27

Describe conus medullar is syndrome

Answer 27

Sudden onset symmetrical paraplegia with mixed upper and lower motoneuron findings caused by injury at T12/L1

Question 28

Describe cauda equina syndrome

Answer 28

Often asymmetrical, lower motor neurone lower limb weakness, with saddle area hypoaesthesia or parathesia, with bladder and bowel areflexia Caused by injuries below L1 damaging the lumbosacral nerve roots

Question 29

What tools can you use to decide if a trauma patient needs c-spine imaging?

Answer 29

1. NEXUS - National Emergency X-Radiography Utilisation Study 2. Canadian C-Spine rules

Question 30

Describe the NEXUS rules

Answer 30

All trauma its should have c-spine imaging unless they meet all of the following criteria 1. No posterior midline cervical spine tenderness 2. No evidence of intoxication 3. Normal level of alertness 4. No focal neuro deficit 5. No painful distracting injuries - including longbow fractures, de-gloving injuries, deep lacs, visceral injuries, crush injuries, large burns, or any other injury causing acute functional impairment

Question 31

What is the sensitivity and specificity of the NEXUS rules?

Answer 31

High sensitivity - 99.6% | Specificity 12.9%

Question 32

How reliable is CT in detecting c-spine injuries?

Answer 32

May miss some significant and unstable injuries in 4%, with approx 0.29% requiring surgical stabilisation

Question 33

What is autonomic dysreflexia?

Answer 33

It's a medical emergency Characterised by acute hypertension due to severe sympathetic stimulation in patients with injuries above T6 It occurs following the resolution of spinal shock. Due to dysregulated sympathetic activation leading to intense vasoconstriction below the level of the lesion Compensatory parasympathetic activation leads to brady cardia, vasodilatation and sweating above the NLOI

Question 34

How is autonomic dysreflexia managed?

Answer 34

Detect and treat the precipitant Sit pt up Antihypertensives - GTN is initially used prior to IV GTN or SNP Some pts develop a chronic, severe AD requiring multiple classes of antihypertensives A BP > 150 in a SCI pt (chronic hypotensive) is life-threatening and may lead to retinal or intracerebral oedema or myocardial ischaemia

Question 35

What are the precipitants of autonomic dysreflexia?

Answer 35

``` Bladder distension Faecal impaction Urinary tract calculi UTI Haemorrhoids and anal fissure Decubitus ulcers Foot disease Procedures e.g. SPC insertion (spinal may prevent) Pelvic stimulations Skeletal injuries ```

Question 36

In which patients should you suspect spinal cord injury?

Answer 36

All severe trauma and head injury | Any surgical procedure with potential for ischamia to the cord e.g. AAA repair and aortic cross-clamping

Question 37

Which patients are at an increased risk of spinal cord injury?

Answer 37

Those with a pre-existing abnormailty - ank spon - degenerative disease - RA - canal stenosis - spinal tumours

Question 38

Which level of the spinal cord do most traumatic injuries occur?

Answer 38

Cervical 60% | In particular C4-6 as this is the most mobile region

Question 39

What non-traumatic conditions can result in spinal cord injury?

Answer 39

``` Tumours of the spinal canal or spinal cord Spinal cord infections Myelitis Vascular malformations Aortic surgery Nutritional deficiencies - esp B12 - resulting in subacute combined degenration of the cod MS MND Acute and chronic demyelinating inflammatory demyelinating polyneuropathies Paraneoplastic Toxic Radiation injury ```

Question 40

What are the mechanisms of injury to the spine?

Answer 40

``` Flexion Rotation Extension Compression Direct ```

Question 41

Discuss flexion injuries to the spine

Answer 41

Usually affects cervical region Common in MVAs and falls Associated bilateral dislocation and associated ligamentous damage

Question 42

Discuss rotational injuries of the spine

Answer 42

Common in cervical or lower thoracic or lumbar regions Associated with motor vehicle passengers wearing lap belts or sustaining side impacts A/w unilateral fracture-dislocation, posterior ligamentous damage, vertebral body fractures and frequently combined with flexion injuries

Question 43

Discuss extension injuries of the spine

Answer 43

Usually elderly with osteoarthritis of spondylosis Minor bony damage with IV disc and spinal cord stretch A/w central cord syndrome

Question 44

Discuss compression injuries of the spine

Answer 44

Common in cervical or lumbar Vertebral body burst fractures into spinal cord Frequently minor neurological damage

Question 45

Discuss direct injuries to the spine

Answer 45

High energy or incisive direct blow Gunshot or knife wounds May result in Brown-Sequard

Question 46

What are the underlying pathophysical mechanisms of primary spinal cord injury

Answer 46

Avulsion or transection Axonal injury Intraparenchymal haemorrhage Ischaemia

Question 47

What pathophysical mechanisms result in secondary injury to the spinal cord?

Answer 47

Cellular hypoxia Ischaemia Cord oedema

Question 48

Which autonomic features suggest high spinal cord injury?

Answer 48

``` Paralytic ileus Faecal incontinence Priaprism Urinary retention Hypothermia due to inability to effectively vasoconstrict ```