1. SPINAL CORD INJURIES Anatomy & Pathophysiology
J C King

2. Definition Insult to spinal cord resulting in a change,
in the normal motor, sensory or autonomic function. This change is either temporary or permanent.

3. Mechanisms:
Direct trauma
Compression by bone fragments / haematoma / disc material
Ischemia from damage / impingement on the spinal arteries

4. Statistics: National Spinal Cord Injury Database { USA Stats }
MVA %
Falls %
Violence %
Sports %
55% cases occur in 16 – 30yrs of age
81.6% are male!

5. South African Statistics (GSH Acute Spinal Cord Injury Unit 2007)
MVA %
Falls %
Gunshot Injuries 11%
Blunt Assault 6%
Diving Accidents 5%
Stab Wounds 4%
Sport Injuries 3%

6. Other causes:
Vascular disorders
Tumours
Infectious conditions
Spondylosis
Iatrogenic
Vertebral fractures secondary to osteoporosis
Development disorders

7. Anatomy : Spinal cord: Extends from medulla oblongata – L1
Lower part tapered to form conus medullaris

9. 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

10. Hence: 31 pairs of spinal nerves:
8 cervical
12 thoracic
5 lumbar
5 sacral
1 coccygeal

12. Dorsal root – sensory fibres
Ventral root – motor fibres
Dorsal and ventral roots join at intervertebral foramen to form the spinal nerve

14. Physiology and function
Grey matter – sensory and motor nerve cells
White matter – ascending and descending tracts
Divided into - dorsal
- lateral
- ventral

16. Tracts :
1) Posterior column:
Fine touch
Light pressure
Proprioception

17. 2) Lateral corticospinal tract :
Skilled voluntary movement
3) Lateral spinothalamic tract :
Pain & temperature sensation

18. 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

19. 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

20. Downloaded from: Rosen's Emergency Medicine (on 29 April 2009 06:34 PM)
© 2007 Elsevier

21. Downloaded from: Rosen's Emergency Medicine (on 29 April 2009 06:34 PM)
© 2007 Elsevier

22. 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 Long finger flexors
T Small hand muscles

23. Lower Limbs :
L Hip flexors
L3,4 - Knee extensors
L4,5 – S1 - Knee flexion
L5 - Ankle dorsiflexion
S1 - Ankle plantar flexion

24. Spinal Cord Injury Classification
Quadriplegia :
injury in cervical region
all 4 extremities affected
Paraplegia :
injury in thoracic, lumbar or sacral segments
2 extremities affected

25. Injury either:
Complete
Incomplete

26. Complete:
Loss of voluntary movement of parts innervated by segment, this is irreversible
Loss of sensation
Spinal shock

27. Incomplete:
Some function is present below site of injury
More favourable prognosis overall
Are recognisable patterns of injury, although they are rarely pure and variations occur

28. 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

29. 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

30. 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

31. Spinal Shock vs Neurogenic 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

32. 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

33. 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

35. Types of incomplete injuries
Central Cord Syndrome
Anterior Cord Syndrome
Posterior Cord Syndrome
Brown – Sequard Syndrome
Cauda Equina Syndrome

36. Central Cord Syndrome :
Typically in older patients
Hyperextension injury
Compression of the cord anteriorly by osteophytes and posteriorly by ligamentum flavum

37. 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

40. 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)

41. Clinically:
Loss of power
Decrease in pain and sensation below lesion
Dorsal columns remain intact

43. 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

45. 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

46. 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)

48. 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

49. 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

50. thank you

51. References:
Andrew T Raftery, et al. Applied Basic Science for Basic Surgical Training. Second edition 2008;8:
ATLS, et al. Student Course Manual. 7th Edition 2004;7:
Keith L Moore et al. Clinically Orientated Anatomy. 3rd Edition1992;4:
Segun T Dawodu et al. eMedicine Specialities. March 2009
K Frielingsdorf, R N Dunn et al. SAMJ. March 2007,Vol. 97,No. 3