Spinal Cord Injuries

Question 1

What is a spinal cord injury?

Answer 1

damage to any part of the spinal cord or nerves at the end of the spinal canal

Question 2

what causes the primary injury in SCI?

Answer 2

trauma, compression, and ischaemia
damage to the intramedullary blood vessels can result in haemorrhage. Due to the limited space in the vertebral canal this haemorrhage can begin to compress the cord and surrounding blood vessels. Vasospasm can also occur and cause further compression and ischaemia to grey matter

Question 3

what are the processes behind secondary injury in SCI?

Answer 3

• energy depletion can begin to occur due to ischaemia, as a result energy dependant processes begin to fail
• release of inflammatory mediators causes oedema and contributes to the limitation of blood flow
• axonal degeneration may commence

Question 4

describe and/or review the clinical snapshot of spinal cord injury

Answer 4

Question 5

What is spinal shock?

Answer 5

The transient loos of all reflexive and autonomic function below the level of cord injury

Question 6

What is the difference between spinal shock and neurogenic shock?

Answer 6

spinal shock is when reflexes are temporarily lost below the level of injury

neurogenic shock is when bradycardia and vasodilation occur resulting in profound hypotension. This is because of the loss of sympathetic innervation below the injury and unnopposed parasympathetic stimualtion affects on the heart. Neurogenic shock only occurs when injury is at T6 or above

Question 7

Describe the process behind hypotension in a SCI at T6 or above

Answer 7

Hypotension can be caused by loss of sympathetic innervation below the injury and therefore unopposed parasympathetic innervation.

• arterial and venous dilation below the level of injury cause reduced systemic vascular resistance and reduced venous return
• the heart rate is decreased as a result of unopposed sympathic activation causing a further reduction in cardiac output

Question 8

What level would you expect to see an SCI if breathing is compromised?

Answer 8

Cervical spine injures (in particular C3-C5 - this is where the phrenic nerve originates which is responsible for the innervation of the diaphragm)

Lower level injuries may preserve innervation of the diaphragm but impact that of the intercostal and abdominal muscles, in turn affecting tidal volume and causing hypoventilation

Question 9

what is piokilothermia?

Answer 9

the inability to maintain core temperature below the injury through shivering, sweating, vasodilation, or vasocontriction

when this occurs the body below the injury moves toward the environmental termperature

Question 10

what are common genitourinary complications seen in spinal cord injury?

Answer 10

• priaprism (prolonged full or partial erection)
• urinary retention*
• paralytic ileus (motor activity of the bowel is impaired)*

*can be seen from abdominal distension

Question 11

what is a complete spinal cord injury?

Answer 11

when all sensorimotor function below the level of injury is lost

Question 12

what is an incomplete spinal cord injury?

Answer 12

when some sensorimotor function remains below the level of injury

Question 13

what three criteria are commonly used to classify spinal cord injuries?

Answer 13

the verteral level, the degree, and the mechanism affected

Question 14

explain the arangement of vertebral levels of the spine and roughly what the nerves from each level innervate

Answer 14

cervical 1-8

thoracic 1-12

lumbar 1-5

Sacral 1-5

Question 15

What funcitons will injuries affecting C5 - C7 affect?

Answer 15

arm movement and strangth as nerves from these areas are responsible for the innervation of the elbow and wrist

Question 16

what functions will an injury involving C3-C5 impact?

Answer 16

breathing, these nerves are responsible for the innervation of the diaphragm. Damanage to these will require advanced respiratory support

Question 17

what functions will injuries to the thoracic spine likely impact?

Answer 17

injuries to the thoricic spine will likley impact ones ability to maintain posture and support breathing as intercostal innervation stems from this area

Question 18

what functions are injuries including the lumbar spine likely to impact?

Answer 18

• hip, knee, and ankle movement
• lower limb strength
• bowel and bladder function

Question 19

what does ‘degree’ mean in terms of classifying a spinal cord injury?

Answer 19

this is where you would describe the injury as complete ro incomplete based on the sensimotor function below the level of injury

This label can’t really be given until a few weeks after the injury when swelling etc. has reduced

Question 20

what does ‘mechanism’ refer to in spinal cord injuries?

Answer 20

This is essentially the moevement involved in the injury. Some examples include; felxion, extension, rotation, and compression

Question 21

describe the mechanisms ‘flexion’ and ‘flexion-extension’

Answer 21

flexion is the movement of moving the head toward the chest, extension is the movement of the chin directly away from the chest. This type of mechanism is common in acceleraiton-decelleration injuries (i.e. in a car)

Question 22

describe the mechanism ‘rotation’

Answer 22

as the name suggests, hard to describe

common in diving accidents

Question 23

describe the mechanism ‘compression’

Answer 23

this can result from a primary injury (e.g. someone landing straight on their head) or can be from secondary swelling. It can also be a result of things like ruptured intervertebral disks, tumours compressing the spinal cord, etc.

Question 24

describe a ‘hyper-extension’ mechanism

Answer 24

extension of the head beyond usual limits. Can often occur as a result of faling and striking the chin

Question 25

define ‘laceration’ in terms of a spinal cord injury

Answer 25

a tear or rip to the spinal cord. Often as a result of trauma such as fractures of the spine or outside objects such as knives or bullets

Question 26

define ‘transection’ in regards to spinal cord injuries

Answer 26

when the spinal cord is completely severed (partial transection may be used when describing large lacerations). Often due to penetrating trauma such as fractures

Question 27

define ‘contusion’ in regards to spinal cord injuries

Answer 27

The vessels supplying the spinal cord rupture and cause haemorrhage in the spinal cord or meninges. Often caused by crushing of the cord in things like falls or acceleration-decelleration injuries.

Question 28

define ‘distraction’ in regards to spinal cord injuries

Answer 28

the process of pulling the spinal cord apart. Caused when a motion forces the top and bottom halves of the body apart. E.g. a seatbelt in an accelleration-decelleration injury

Question 29

define ‘spinal concussion’

Answer 29

motor and sensory defecits as a result of a blow to the spinal cord. There is no apparent damage done to the spinal cord in this case and defecits will subside after a short period of time

Question 30

label the motor pathway and sensory pathways as either ascending or descending

Answer 30

motor = descending

sensory = ascending

Question 31

briefly describe anterior cord syndrome

Answer 31

• front (anterior) of the spinal cord is affected
• loss of distal motor function and some sensory function (such as pain and temp)
• often retain sensations of vibration, light touch, and pressure
• most often caused by mechanical events such as trauma or disk herniation

Question 32

briefly describe central cord syndrome

Answer 32

• commonly caused by hyperextension of c-spine
• contusion to centre of the cord
• can experience significant upper extremity weakness and distal motor loss
• temperature and pain sesations are generally lost, proprioception and vibration are generally maintained

Question 33

briefly describe brown-sequard syndrome

Answer 33

• transection (severed) across half of spinal cord
• ipsilateral (side of injury) loss of motor function and proprioception
• contralateral (unaffected side) loss of pain and temperature sensations

Question 34

briefly describe cauda equina syndrome

Answer 34

• commonly caused by compression or trauma concerning the lumbosacral nerve roots beneath the spinal cord
• common causes are tumour, trauma, intervertabral disk herniation/rupture
• most often unilateral and asymetric neurological defecits but can be bilateral
• lower extremity weakness, reduced/absent reflexes, urinary incontinence, urinary retention, and constipation are common
• often associated with lower back or sciatic pain

Question 35

What does on road management of a spinal cord injury include?

Answer 35

airway, breathing, and circulation are a priority in the management of spinal cord injury.

• injuries above C5 will likely required airway support and intubation
• circulatory support will be necessary in the development of neurogenic shock or hypovolaemic shock as a result of significant internal bleeding
• C-spine should be cared for and immobilised with consideration of the potential for head injury and increased ICP-

Question 36

what is autonomic dysreflexia?

Answer 36

a medical emergency that can develop in people with an injury at T6 or higher. It is characterised by an exagerated and unopposed autonomic response as a result of noxious stimuli below the level of injury. This stimuli results in a reflex sympathetic outflow causing vasoconstriction, this in turn causes severe hypertension and reflexive parasympathetic nervous system response causing bradycardia.

Question 37

explain the patholophysiology behind autonomic dysreflexia

Answer 37

noxious stimuli occurs > stimuli sensed by nociceptors > stimuli relayed via spinothalamic tract > message blocked by lesion at T6 or above > reflexive sympathetic nervous system response > causes vasoconstriction (hypertension and pallor below injury level) > baroreceptors sense hypertension and relay message to medulla oblongata > parasympathetic nervous system responds > PSNS response causes bradycardia, headache > PSNS caused vasodilation above injury site results in flushed skin and diaphoresis above injury level

Question 38

what are the most common noxious stimuli causes of autonomic dysreflexia?

Answer 38

• irritation or obstruction of the bladder or bowel
• a pressure area or wound infection
• a fracture beneath lesion
• kinks, obstruction or infection of urinary catheter
• pressure from things like creases, zips, and buttons can also be a cause

Question 39

what is the most important factor in the resolution of autonomic dysreflexia?

Answer 39

identifying and correcting the cause of noxious stimuli

Question 40

what is the biggest concern or complication of autonomic dysreflexia?

Answer 40

profound hypertension

hypertension can exceed 250mmHg and greatly increase the risk of seizure, haemorrhage, and myocardial infarction