1. Spinal cord injuries

2. Overview: Anatomy of the spinal cord Case presentation
Spinal cord injuries
Classification
Complete and incomplete syndromes
Respiratory complications of spinal cord injuries
ICU management of spinal cord injuries
Pharmacological management

3. Gross anatomy
Begins at the foramen magnum of the skull, where it is continuous with the medulla oblongata
Cervical enlargement gives rise to the brachial plexus
Lumbar enlargement gives rise to the lumbosacral plexus
Tapers inferiorly to the conus medullaris – from here the filum terminale attaches to the coccyx
Lower end of the spinal cord lies at the lower border of L1
Vertebral column is much longer than the spinal column, so the cord segments do not correspond numerically to the vertebral bodies

4. Columns of the spinal cord
Spinal column stabilised by three major ligaments;
Anterior longitudinal ligament
Posterior longitudinal ligament
Ligamentum flavum
Anterior column: Anterior 2/3 vertebral bodies and the anterior ligament
Middle column: Posterior 1/3 vertebral bodies and the posterior ligament
Posterior column: Ligamentum flavum and everything else
Injury involving > one column is considered unstable

6. Spinal cord structure
Inner core of grey matter, surrounded by an outer covering of white matter
Grey matter is arranged in an ‘H- shape’, with anterior and posterior horns, joined by a thin grey commissure which contains the central canal
The T1-L3 segments also contain a lateral grey horn

8. Grey matter of the spinal cord
The anterior horn is divided into medial, central and lateral columns
Medial group is present in most segments  innervating the skeletal muscles of the neck and trunk
Central group is the smallest and is present in some cervical and lumbosacral segments
Lateral group is present in the cervical and lumbosacral segments  innervates the skeletal muscles of the limbs
Posterior horn has four different groups of nerve cells
Substantia gelatinosa group
Nucleus propius
Nucleus dorsalis
Visceral afferent nucleus
Lateral grey horns contain pre-ganglionic sympathetic fibres

9. Tracts of the spinal cord
Ascending (sensory):
Dorsal (posterior) columns: deep touch, proprioception, vibration
Lateral spinothalamic: pain and temperature
Anterior spinothalamic: light touch
Descending (motor):
Lateral corticospinal: voluntary motor
Anterior corticospinal: voluntary skilled motor
Rubrospinal: control of movement
Vestibulospinal: posture and balance
Tectospinal: reflex postural movements in response to visual stimuli

11. Spinal cord injuries Causes:
Majority caused by MVAs; falls; iatrogenic
Mostly young males, but the other demographic includes older people with concurrent degenerative spinal canal narrowing
Frequently associated with other conditions:
Shock syndromes
Other injuries

12. A likely story…

13. Say hello to Jim.
85 year old male who slipped backwards and hit head on towbar behind car
Presented to Tenterfield Hospital, then T/F to Armidale, where CT showed unstable C4/5 #
Transferred to JHH for NSx R/V
Conscious and spontaneously breathing
Hard collar in situ, but poorly fitting
GCS 13: E3V4M6, PEARL
B/G: metastatic prostate ca, HTN, T2DM

14. Jim’s imaging
Unstable C4/5 fracture

15. Further examination… Normal cranial nerve examination
Decreased strength (2/5) and absent reflexes bilaterally in upper limbs
Decreased pain and temperature sensation bilateral hands
Normal strength (5/5), reflexes and sensation in bilateral lower limbs
Developed urinary retention

16. American Spinal Injury Association Neurological impairment scale

17. Classifications Quadriplegia Paraplegia Complete Incomplete
Injury to the cervical spine, leading to impairment in the arms, trunk, pelvis and legs
Paraplegia
Injury to the thoracic, lumbar or sacral segments, leading to impairment in the trunk, legs and pelvic organs
Complete
No motor or sensory function below the affect level
Incomplete
Some preserved motor or sensory function below the affected level

18. Complete injury No voluntary anal contraction 0/5 distal motor score
0/2 sensory score
Bulbocavernous reflex present

19. Incomplete spinal cord injuries
Anterior cord syndrome
Central cord syndrome
Brown-Sequard syndrome
Posterior cord syndrome

20. Anterior spinal cord syndrome
Injury to the anterior spinal cord caused by either direct compression of the spinal cord, or damage to the anterior spinal artery
Usually from a flexion/compression injury
Bilateral loss of pain, temperature and light touch below the lesion due to disruption of the anterior and lateral spinothalamic tracts
Motor dysfunction due to the disruption of the anterior corticospinal tracts, and damage to the anterior grey horn neurons
Worst prognosis of incomplete SCI
10-20% chance motor recovery
Anterior

21. Central spinal cord syndrome
Most common incomplete spinal cord injury
Often in the elderly with extension injury mechanisms, due to anterior osteophytes and posterior infolded ligaments
Motor dysfunction due to disruption of the lateral corticospinal tracts and damage to the anterior grey horn neurons
Bladder and bowel involvement
Bilateral loss of pain, temperature and light touch due to disruption of the spinothalamic tracts
Sacral sparing
Good prognosis, but unlikely to regain full function
Anterior

22. Brown-Sequard syndrome
Caused by complete cord hemitransection
Ipsilateral motor dysfunction, with LMN weakness at the level of the injury, and UMN signs below the injury
Ipsilateral proprioception and vibration loss due to posterior column damage
Contralateral pain and temperature loss 2-3 segments below the lesion due to disruption of the spinothalamic tracts
Good prognosis

23. Posterior cord syndrome
Rare syndrome
Most commonly caused by vascular compromise, with occlusion to the posterior spinal artery
Sensory dysfunction with ipsilateral loss of proprioception and vibration, and preservation of pain and temperature
Anterior

24. Cauda equina syndrome
Caused by damage to the cauda equina, a collection of S1-L5 nerves
Technically a peripheral nerve lesion, so will cause lower motor neuron signs
Presentation:
Saddle anaesthesia, bilateral lower limb sensorimotor loss and pain, bowel and bladder symptoms (especially urinary retention)
Absent or reduced lower limb reflexes, decreased rectal tone
MRI best to evaluate nerve compression
Needs urgent surgical decompression within 48 hours

25. Jim’s progress notes… Admitted under NSx
Few episodes of vomiting on ward, during which he likely aspirated
RRT on ward for respiratory arrest – intubated and T/F to ICU
Some more stuff happened….
Improved and ready to trial extubation….
Unfortunately, he failed extubation due to hypoxia
Why?

26. Respiratory complications with SCI
Spinal cord level
Muscle involvement
Effect on respiration
Clinical consequence
C1-3
Complete paralysis of all respiratory muscles
Vital capacity only 5-10% of normal; absent cough
Apnoea and immediate death
C3-6
Varied impairment of diaphragmatic contraction
Vital capacity 20% of normal; weak and ineffective cough
Ventilation necessary in acute stages; majority will be weaned from mechanical ventilation
C6-8
Diaphragm and accessory cervical inspiratory muscles intact. Intercostals and abdominal muscles intact
Expiration entirely passive. Secretion retention. No respiratory failure unless coexisting lung/chest injury/illness
T2-4
Vital capacity 30-50% normal, and weak cough

27. SCI effects on breathing
Loss of intercostal function:
Failure of AP expansion of the ribcage
Chest wall sucked in during diaphragmatic contraction
Loss of lower thoracic segment innervation:
Diaphragm starts in a flatter position, which decreases contraction pressure
Loss of abdominal muscle tone:
As the diaphragm flattens, abdominal contents are pushed outwards and the lower ribcage is pulled inwards, causing paradoxical see-saw breathing
Diaphragm is pulled down by the weight of the abdomen
Inefficient, rapid, shallow breathing results, with more dead space ventilation
Abdominal muscle weakness results in decreased ability to cough and clear secretions

28. ICU management of SCI patients

29. Respiratory management
Airway management
Physiotherapy
Posture
Mucolytics
Abdominal binding
Monitor for infection
Bronchoscopy

30. Longer term respiratory care
Tracheostomy
More comfortable; minimise laryngeal damage; less dead space compared to ETT; associated with fewer respiratory infections
Weaning from ventilation
Portex sprints are as effective or better than PS weaning, with both superior to SIMV weaning

31. Cardiovascular complications after SCI
Neurogenic shock
Occurs with lesions above T6 due to loss of sympathetic tone and unopposed parasympathetic tone
Vasodilation and hypotension; bradycardia
Thromboembolism
Due to immobility and venous stasis
Sympathetic hyperreflexia
Unopposed sympathetic tone below the level of injury, triggered by sensory stimuli

32. Gastrointestinal complications after SCI
Delayed gastric emptying and ileus
Common and may last 2-3 weeks
Aperients, early feeding, NGT, prokinetic agents
Gastric stress ulceration
PPI prophylaxis
Constipation

33. Metabolic system considerations
Temperature regulation
Hypothermic due to vasodilation
Hyperthermic due to inability to sweat below level of injury
Hyperglycaemia
Common due to stress response
Worsens ischaemic neurological injury

34. Pharmacological treatment of SCI
Steroids
Previously, high dose methylprednisone was standard of care for SCI
Since shown to significantly increase mortality in patients, compared to placebo
NOGO-A antibody
NOGO-A is an inhibitory molecule that prevents neuronal plasticity and axonal regeneration
Current clinical trial to determine effects of an intrathecal infusion of NOGO-A antibody

35. References
Snell. Clinical neuroanatomy. 7th Ed. (2010). Lippincott Williams and Williams: Philadelphia
J Patten. Neurological differential diagnosis. 2nd Ed. (1996). Springer: London
M Denton, J McKinlay. Cervical cord injury and critical care. Continuing education in Anaesthesia and Critical Care. (2009). Vol 9: No. 3
Stahel et al. Management strategies for acute spinal cord injury: current options and future perspectives. Current Opinion Critical Care. (2012). 18:
A Neill. Basic neuroanatomy for the critically ill. SMACC.
C Wheeless. Anterior cord syndrome. Wheeless’ textbook of orthopaedics..Last updated: 25/4/12. Date accessed: 30/6/13
S Hishmeh. Posterior cord syndrome. Orthopaedics:one. Last updated: 22/6/09. Date accessed: 30/6/13
D Moore. Spinal cord injuries. Ortho bullets. Last updated: 20/5/13. Date accessed: 30/6/13