Spinal cord injuries

Spinal cord injuries
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
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
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
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
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
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Substantia gelatinosa group
Nucleus propius
Nucleus dorsalis
Visceral afferent nucleus
• Lateral grey horns contain pre-ganglionic sympathetic fibres
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):
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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
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
A likely story…
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
Jim’s imaging
• Unstable C4/5 fracture
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
American Spinal
Injury Association
Neurological
impairment scale
Classifications
• Quadriplegia
– 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
Complete injury
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No voluntary anal contraction
0/5 distal motor score
0/2 sensory score
Bulbocavernous reflex present
Incomplete spinal cord injuries
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Anterior cord syndrome
Central cord syndrome
Brown-Sequard syndrome
Posterior cord syndrome
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
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
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
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
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
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?
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
T2-4
Expiration entirely
passive. Secretion
retention. No respiratory
failure unless coexisting
lung/chest injury/illness
Vital capacity 30-50%
normal, and weak cough
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
ICU management of SCI patients
Respiratory management
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Airway management
Physiotherapy
Posture
Mucolytics
Abdominal binding
Monitor for infection
Bronchoscopy
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
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
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
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
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
References
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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). 18:651-660
A Neill. Basic neuroanatomy for the critically ill. SMACC. http://smacc.net.au/2013/02/basic-neuroanatomy-for-thecritically-ill/
C Wheeless. Anterior cord syndrome. Wheeless’ textbook of orthopaedics..Last updated: 25/4/12.
http://www.wheelessonline.com/ortho/anterior_cord_syndrome Date accessed: 30/6/13
S Hishmeh. Posterior cord syndrome. Orthopaedics:one. Last updated: 22/6/09.
http://www.orthopaedicsone.com/display/Main/Posterior+cord+syndrome Date accessed: 30/6/13
D Moore. Spinal cord injuries. Ortho bullets. Last updated: 20/5/13. http://www.orthobullets.com/spine/2006/spinalcord-injuries Date accessed: 30/6/13