SPINAL CORD INJURIES
Anatomy & Pathophysiology
J C King
Definition
Insult to spinal cord resulting in a change,
in the normal motor, sensory or autonomic
function. This change is either temporary
or permanent.
Mechanisms:
i) Direct trauma
ii) Compression by bone fragments /
haematoma / disc material
iii) Ischemia from damage / impingement on
the spinal arteries
Statistics:
National Spinal Cord Injury Database
{ USA Stats }
• MVA
44.5%
• Falls
18.1%
• Violence
16.6%
• Sports
12.7%
• 55% cases occur in 16 – 30yrs of age
• 81.6% are male!
South African Statistics (GSH Acute Spinal Cord
Injury Unit 2007)
• MVA
56%
• Falls
16%
• Gunshot Injuries
11%
• Blunt Assault
6%
• Diving Accidents
5%
• Stab Wounds
4%
• Sport Injuries
3%
Other causes:
• Vascular disorders
• Tumours
• Infectious conditions
• Spondylosis
• Iatrogenic
• Vertebral fractures secondary to osteoporosis
• Development disorders
Anatomy :
Spinal cord:
• Extends from medulla oblongata – L1
• Lower part tapered to form conus
medullaris
On the surface :
• Deep anterior median fissure
• Shallower posterior median sulcus
Spinal cord segment :
• Section of the cord from which a pair of
spinal nerves are given off
Hence:
31 pairs of spinal nerves:
8 cervical
12 thoracic
5 lumbar
5 sacral
1 coccygeal
• Dorsal root – sensory fibres
• Ventral root – motor fibres
• Dorsal and ventral roots join at
intervertebral foramen to form the spinal
nerve
Physiology and function
• Grey matter – sensory and motor nerve
cells
• White matter – ascending and descending
tracts
• Divided into - dorsal
- lateral
- ventral
Tracts :
1) Posterior column:
• Fine touch
• Light pressure
• Proprioception
2) Lateral corticospinal tract :
• Skilled voluntary movement
3) Lateral spinothalamic tract :
• Pain & temperature sensation
• Posterior column and lateral corticospinal
tract crosses over at medulla oblongata
• Spinothalamic tract crosses in the spinal
cord and ascends on the opposite side
NB to understand this as it helps to
understand the clinical features of
injury patterns and the neurological
deficit
Dermatomes
• Area of skin innervated by sensory axons
within a particular segmental nerve root
• Knowledge is essential in determining
level of injury
• Useful in assessing improvement or
deterioration
Downloaded from: Rosen's Emergency Medicine (on 29 April 2009 06:34 PM)
© 2007 Elsevier
Downloaded from: Rosen's Emergency Medicine (on 29 April 2009 06:34 PM)
© 2007 Elsevier
Myotomes :
• Segmental nerve root innervating a muscle
• Again important in determining level of injury
• Upper limbs:
C5 - Deltoid
C 6 - Wrist extensors
C 7 - Elbow extensors
C 8 - Long finger flexors
T 1 - Small hand muscles
• Lower Limbs :
L2 - Hip flexors
L3,4 - Knee extensors
L4,5 – S1 - Knee flexion
L5 - Ankle dorsiflexion
S1 - Ankle plantar flexion
Spinal Cord Injury Classification
• Quadriplegia :
injury in cervical region
all 4 extremities affected
• Paraplegia :
injury in thoracic, lumbar or sacral
segments
2 extremities affected
Injury either:
1) Complete
2) Incomplete
Complete:
i) Loss of voluntary movement of parts
innervated by segment, this is
irreversible
ii) Loss of sensation
iii) Spinal shock
Incomplete:
i)
Some function is present below site of
injury
ii) More favourable prognosis overall
iii) Are recognisable patterns of injury,
although they are rarely pure and
variations occur
Injury defined by ASIA Impairment
Scale
ASIA – American Spinal Injury Association :
A – Complete: no sensory or motor function
preserved in sacral segments S4 – S5
B – Incomplete: sensory, but no motor
function in sacral segments
C – Incomplete: motor function preserved
below level and power graded < 3
D – Incomplete: motor function preserved
below level and power graded 3 or more
E – Normal: sensory and motor function
normal
Muscle Strength Grading:
• 5 – Normal strength
• 4 – Full range of motion, but less than
normal strength against
resistance
• 3 – Full range of motion against gravity
• 2 – Movement with gravity eliminated
• 1 – Flicker of movement
• 0 – Total paralysis
Spinal Shock vs Neurogenic Shock
Spinal Shock :
• Transient reflex depression of cord function below level
of injury
• Initially hypertension due to release of catecholamines
• Followed by hypotension
• Flaccid paralysis
• Bowel and bladder involved
• Sometimes priaprism develops
• Symptoms last several hours to days
Neurogenic shock:
• Triad of i) hypotension
ii) bradycardia
iii) hypothermia
• More commonly in injuries above T6
• Secondary to disruption of sympathetic
outflow from T1 – L2
• Loss of vasomotor tone – pooling of blood
• Loss of cardiac sympathetic tone – bradycardia
• Blood pressure will not be restored by fluid
infusion alone
• Massive fluid administration may lead to
overload and pulmonary edema
• Vasopressors may be indicated
• Atropine used to treat bradycardia
Types of incomplete injuries
i)
Central Cord Syndrome
ii)
Anterior Cord Syndrome
iii) Posterior Cord Syndrome
iv) Brown – Sequard Syndrome
v)
Cauda Equina Syndrome
i)
Central Cord Syndrome :
•
•
•
Typically in older patients
Hyperextension injury
Compression of the cord anteriorly by
osteophytes and posteriorly by
ligamentum flavum
• Also associated with fracture dislocation
and compression fractures
• More centrally situated cervical tracts tend
to be more involved hence
flaccid weakness of arms > legs
• Perianal sensation & some lower extremity
movement and sensation may be
preserved
ii) Anterior cord Syndrome:
• Due to flexion / rotation
• Anterior dislocation / compression fracture
of a vertebral body encroaching the ventral
canal
• Corticospinal and spinothalamic tracts are
damaged either by direct trauma or
ischemia of blood supply (anterior spinal
arteries)
Clinically:
• Loss of power
• Decrease in pain and sensation below
lesion
• Dorsal columns remain intact
ii) Posterior Cord Syndrome:
Hyperextension injuries with fractures
of the posterior elements of the vertebrae
•
•
Clinically:
Proprioception affected – ataxia and
faltering gait
Usually good power and sensation
iv) Brown – Sequard Syndrome:
• Hemi-section of the cord
• Either due to penetrating injuries:
i) stab wounds
ii) gunshot wounds
• Fractures of lateral mass of vertebrae
Clinically:
• Paralysis on affected side (corticospinal)
• Loss of proprioception and fine
discrimination (dorsal columns)
• Pain and temperature loss on the opposite
side below the lesion (spinothalamic)
v) Cauda Equina Syndrome:
•
Due to bony compression or disc protrusions
in lumbar or sacral region
Clinically
• Non specific symptoms – back pain
- bowel and bladder dysfunction
- leg numbness and weakness
- saddle parasthesia
In conclusion;
Spinal Cord Injuries:
• Devastating event to both patient and
family.
• Huge impact on society
• After receiving First – World care in
tertiary institutions, many of our
patients return to impoverished
communities
• Here they face huge challenges in terms
of survival
thank you
References:
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Basic Surgical Training. Second edition 2008;8:219223
2. ATLS, et al. Student Course Manual. 7th Edition
2004;7:177-204
3. Keith L Moore et al. Clinically Orientated Anatomy. 3rd
Edition1992;4:359-369
4. Segun T Dawodu et al. eMedicine Specialities. March
2009
5. K Frielingsdorf, R N Dunn et al. SAMJ. March
2007,Vol. 97,No. 3