Spinal Injuries (Sources: OH's, Revision notes) Flashcards
What are the commonest mechanisms leading to SCI?
MVA - cars, motor bikes, bicycles
Falls - domestic and industrial
Sports-related
Diving
Briefly, describe the anatomy of the spinal cord
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
Where does the sympathetic nerve supply originate?
Originates from the intermediolateral column of segments T1-L2
Where does the parasympathetic outflow originate?
S2-S4 and supplies pelvic viscera
What are the 2 phases of a SCI?
Primary Injury and secondary injury
Describe the primary phase of SCI
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
Describe the secondary phase of SCI
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
What are the potential complications that can arise from C-spine collars?
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
What are the issues that arise in the acute phase following a SCI?
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
What are the possible indications for I+V in SCI patients?
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
Why does hypotension occur in SCI patients?
Loss of vasomotor tone below NLOI
Bradycardia if NLOI is above T1
Concurrent injury resulting in haemorrhage
How is hypotension in SCI patients managed?
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
Why do patients with SCI become bradycardia and how is it managed?
Low of cardiac sympathetic innervation
May require anticholinergics (e.g. atropine), chronotropics (e.g. isoprenaline) or pacing
Why do patients with SCI get gastroparesis and how can it be treated?
Loss of gastrointestinal sympathetic innervation
Managed with an NGT
What is the definition of tetraplegia?
Motor and/or sensory deficits affecting both upper and lower limbs, due to cervical SCI
What is the definition of paraplegia?
Motor and/or sensory deficits affecting only the lower limbs due to SCI below the cervical region
What is the neurological level of injury?
The most caudal cord segment with normal motor and sensory function bilaterally
What is a complete SCI?
Absence of both motor and sensory function in the lowest sacral segments (i.e. no anal tone an no sensation)
What is the zone of partial preservation?
Only used in describing complete SCI
Refers to the spinal segments that have any motor or sensory function below the NLOI
What is spinal shock?
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
What is neurogenic shock?
A form of distributive shock following SCI due to loss of sympathetic tone in peripheral vasculature
What are the possible signs of SCI in an unconscious/uncooperative patient?
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
What instrument tool should be used to diagnose and classify SCIs?
The American Spinal Injury Association (ASIA) impairment scale
Involves a bilateral sensory and motor exam, DRE, and determines NLOI and completeness
What is central cord syndrome?
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
Describe anterior cord syndrome
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
Describe Brown-Sequard syndrome
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
Describe conus medullar is syndrome
Sudden onset symmetrical paraplegia with mixed upper and lower motoneuron findings caused by injury at T12/L1
Describe cauda equina syndrome
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
What tools can you use to decide if a trauma patient needs c-spine imaging?
- NEXUS - National Emergency X-Radiography Utilisation Study
- Canadian C-Spine rules
Describe the NEXUS rules
All trauma its should have c-spine imaging unless they meet all of the following criteria
- No posterior midline cervical spine tenderness
- No evidence of intoxication
- Normal level of alertness
- No focal neuro deficit
- 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
What is the sensitivity and specificity of the NEXUS rules?
High sensitivity - 99.6%
Specificity 12.9%
How reliable is CT in detecting c-spine injuries?
May miss some significant and unstable injuries in 4%, with approx 0.29% requiring surgical stabilisation
What is autonomic dysreflexia?
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
How is autonomic dysreflexia managed?
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
What are the precipitants of autonomic dysreflexia?
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
In which patients should you suspect spinal cord injury?
All severe trauma and head injury
Any surgical procedure with potential for ischamia to the cord e.g. AAA repair and aortic cross-clamping
Which patients are at an increased risk of spinal cord injury?
Those with a pre-existing abnormailty
- ank spon
- degenerative disease
- RA
- canal stenosis
- spinal tumours
Which level of the spinal cord do most traumatic injuries occur?
Cervical 60%
In particular C4-6 as this is the most mobile region
What non-traumatic conditions can result in spinal cord injury?
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
What are the mechanisms of injury to the spine?
Flexion Rotation Extension Compression Direct
Discuss flexion injuries to the spine
Usually affects cervical region
Common in MVAs and falls
Associated bilateral dislocation and associated ligamentous damage
Discuss rotational injuries of the spine
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
Discuss extension injuries of the spine
Usually elderly with osteoarthritis of spondylosis
Minor bony damage with IV disc and spinal cord stretch
A/w central cord syndrome
Discuss compression injuries of the spine
Common in cervical or lumbar
Vertebral body burst fractures into spinal cord
Frequently minor neurological damage
Discuss direct injuries to the spine
High energy or incisive direct blow
Gunshot or knife wounds
May result in Brown-Sequard
What are the underlying pathophysical mechanisms of primary spinal cord injury
Avulsion or transection
Axonal injury
Intraparenchymal haemorrhage
Ischaemia
What pathophysical mechanisms result in secondary injury to the spinal cord?
Cellular hypoxia
Ischaemia
Cord oedema
Which autonomic features suggest high spinal cord injury?
Paralytic ileus Faecal incontinence Priaprism Urinary retention Hypothermia due to inability to effectively vasoconstrict
