Neurosurgery JC031: Paraplegia: Spinal Cord Compression, Transverse Myelitis, Spinal Dysraphism, Neuroimaging 3: Spinal Cord

Question 1

Plegia

Answer 1

Weakness of limb

4 types:
1. Monoplegia (one limb)
2. Hemiplegia (half of body)
3. Paraplegia (lower half)
4. Tetraplegia

Question 2

Revision: Spinal anatomy

Answer 2

31 pairs of spinal nerves:
- C1-C8 (8 pairs) (vs C1-7 vertebral bodies)
- T1-T12 (12 pairs)
- L1-L5 (5 pairs)
- S1-S5 (5 pairs)

Spinal cord ends at higher level than respective spinal canal (i.e. vertebral body)
- e.g. T10 spinal cord level = T12 / L1 vertebral body

Spinal tracts:
Ascending (Afferent / Sensory):
- **Posterior Spinothalamic tract (DC tract): Fasciculus gracilis, Fasciculus cuneatus (sacral medial, cervical lateral)
- **Anterior, Lateral Spinothalamic tracts (Pain + Temperature) (cervical medial, sacral lateral)
- Anterior, Posterior Spinocerebellar tracts
- Spinoolivary tract
- Spinotectal tract

Descending (Efferent / Motor):
- ***Lateral Corticospinal tract (80%, main bulk of fibres) (cervical medial, lower limb lateral)
- Rubrospinal
- Reticulospinal (anterior, lateral)
- Tectospinal
- Vestibulospinal

Question 3

Motor pathway

Answer 3

Lateral + Anterior Corticospinal tract
—> Anterior horn cells
—> Ventral nerve root (exit at each spinal level, carrying motor neurons)
(Ventral nerve root + Dorsal nerve root (Sensory modality) —> Spinal nerve root)
—> Plexus
—> Peripheral nerve innervating muscles

Question 4

UMN vs LMN

Answer 4

UMN:
- Lesion above anterior horn cells
- Hypertonic muscle
- Clonus present
- No fasciculation
- Disuse atrophy (delayed)
- Hyperreflexic
- Up-going plantar (Babinski’s sign)

LMN:
- Lesion at ***anterior horn cells / ventral nerve root
- Hypotonic muscle
- Clonus absent
- Have fasciculation
- Acute wasting of muscles
- Hyporeflexic
- Down-going plantar

Question 5

Myotome

Answer 5

***C3-5: Diaphragm

C5: Elbow flexors
C6: Wrist extensors
C7: Elbow extensors
C8: Finger extensors
T1: Intrinsic hand muscles

L2: Hip flexors
L3: Knee extensors
L4: Ankle dorsiflexors
L5: Long toe extensors
S1: Ankle plantar flexors

Question 6

Sensation / Ascending tracts

Answer 6

Posterior / Dorsal column:
- Fine touch (2 point discrimination)
- Proprioception
- Pressure
- Vibration
- **Decussate in Medulla oblongata —> **Medial lemniscus —> Thalamus —> Primary somatosensory cortex in parietal lobe

Anterior, Lateral Spinothalamic tract:
- Pain
- Temperature
- **Decussate in Spinal cord —> **Anterior, Lateral Spinothalamic tract —> Thalamus —> Primary somatosensory cortex in parietal lobe

Question 7

Sensory loss

Answer 7

Spinal nerve lesion:
- Segmental loss: ***All modalities loss at a single dermatome

Spinal cord lesion (Long tract loss):
- **Sensory level
- **Modalities loss depends on site of lesion

Question 8

Dermatome sensory level

Answer 8

T4: Nipple
T7: Xyphisternum
T10: **Umbilicus
L1: **Groin / Inguinal region

C5-T1: Upper limb
L2-S2: Lower limb

Question 9

Conus medullaris, Cauda equina

Answer 9

Conus medullaris:
- end of spinal cord proper (L1/2 vertebral level)
- Lesion at above (i.e. Spinal cord): UMN lesion
- Lesion: ***Mixed UMN + LMN lesion

Cauda equina:
- Lower lumbosacral nerve root exiting spinal cord before leaving spinal canal
- Lesion: LMN lesion

Question 10

Cauda equina syndrome

Answer 10

1. **Saddle anaesthesia (loss of sensation of **sacral dermatome (S2-5)
2. **Sphincter dysfunction
   - Bladder: Painless acute urinary **retention
   - Bowel: ***Constipation
   - Irreversible unless very early intervention

Question 11

Spinal cord blood supply

Answer 11

1. Segmental artery (Segmental metameric system)
   - from **Aorta
   - paired
   - regress, prominent ones remain (Biggest: **Artery of Adamkiewicz: Lower thoracic, Higher lumbar level)
   - join Anterior spinal artery
2. Anterior spinal artery
   - from **Vertebral artery in brain
   - anterior midline of spinal cord
   - anastomose with Posterior spinal artery (circumferentially + inside)
   - main contributor: **Artery of Adamkiewicz —> lower thoracic / upper lumbar level
3. Posterior spinal artery
   - from ***Vertebral artery in brain
   - paired
   - posterior surface of spinal cord
   - anastomose with Anterior spinal artery (circumferentially + inside)

Question 12

Spinal cord syndromes

Answer 12

Complete cord transaction (所有無曬)
- Complete paralysis
- Sensory loss below
- Sphincter dysfunction

Incomplete injury (Pattern of symptoms depend on location of spinal cord damaged)
1. Hemi-transection (Brown-Sequard syndrome)
2. Central cord syndrome
3. Anterior cord syndrome
4. Posterior cord syndrome
5. Variation depends on exact site of damage

Question 13

1. Hemi-transection (Brown-Sequard syndrome)

Answer 13

Motor:
1. Ipsilateral UMN sign (Spastic paralysis) below level of lesion (due to damage to descending lateral corticospinal tract)
(∵落黎個陣已經係medulla cross左)

2. Ipsilateral LMN sign (Flaccid paralysis) ***at the level of lesion due to direct damage to ventral and dorsal grey matter

Sensory:
3. Ipsilateral loss of proprioceptive sensation, 2-point discrimination below level of lesion (due to damage to ascending dorsal columns)
(∵已經未去到medulla cross已經壞左)

4. Contralateral loss of pain and temperature sensation ***a few levels below lesion (∵ at level of / a few levels below the lesion some 2nd order neurons do not cross until climb up a few levels)
   (∵爬上幾層先cross)
5. Ipsilateral loss of ALL sensations ***at the level of lesion due to direct damage to ventral and dorsal grey matter

Question 14

Horner’s syndrome

Answer 14

Lesion affecting ***Cervical spine, if Sympathetic trunk damaged:
1. Miosis (vs CN3 palsy: Mydriasis)
2. Ptosis
3. Enophthalmos
4. Anhydrosis (↓ sweating)

Question 15

2. Central cord syndrome

Answer 15

Causes:
- **Hyperextension injury
- **Syringomyelia
- Intrinsic spinal cord tumour

Clinical features:
1. Segmental loss
- Sensory: Decussating secondary sensory neurons affected —> Bilateral Upper limb pain / numbness > Lower limb numbness

2. Long tract sign
   - Medial fibres affected first (cervical fibres)
   - Motor: Upper limb > Lower limb weakness
   - ***Sacral sparing

(MUDS:
- **Motor > Sensory
- **Upper > Lower limb
- ***Distal > Proximal
- Extension injury)

Question 16

3. Anterior cord syndrome

Answer 16

Causes:
- Anterior spinal artery infarct
- External compression

Clinical features:
1. **Paraplegia (damaged motor tract + anterior horn cells)
2. **Spinothalamic loss
3. ***Intact proprioception, 2 point discrimination (fine touch) (∵ Intact Dorsal column)

Question 17

4. Posterior cord syndrome

Answer 17

Rare

Clinical features:
1. Pain and paresthesia in upper limb + trunk (∵ **spared pain + temperature sensation)
2. **Bilateral loss of fine touch, proprioceptive, vibration sensation below the lesion
3. Motor: Mild UL paraparesis

Question 18

Grading severity of injury: American Spinal Injury Association (ASIA) Classification

Answer 18

A to E:
- A: Complete spinal cord injury (no sensory / motor function preserved below level)
- E: Normal (sensory / motor function preserved)

Sensory: Pinprick (Spinothalamic) + Touch (DC) in each dermatome

Question 19

Spinal shock

Answer 19

2 meanings:
1. **Flaccid paralysis + **Areflexia for 1-2 weeks after injury
- Acute damage to spinal cord —> ***Denervation response —> Completely Areflexic + Weak muscle tone
- Return of anal tone / reflex usually signifies end of spinal shock —> Can properly assess motor + sensory function again —> Determine permanent deficits
- Phase 1 (0-1 day): Areflexia (Loss of descending facilitation)
- Phase 2 (1-3 day): Initial reflex return (Denervation supersensitivity)
- Phase 3 (1-4 week): Initial Hyperreflexia (Axon-supported synapse growth)
- Phase 4 (1-12 month): Final Hyperreflexia (Soma-supported synapse growth)

SpC Revision:
- Period of temporary loss of function after injury (hours - days)
- No motor / sensory function: cannot differentiate between complete / incomplete injury
- All reflexes absent
- Spinal shock is over if bulbocavernosus / anal wink reflex has returned (these are lowest local reflexes mediated by spinal cord level)
- Assess for motor / sensory function ONLY after spinal shock is over

(Web:
- loss of muscle tone and spinal reflexes below the level of a severe spinal cord lesion
- this “shock” does not imply a state of circulatory collapse (vs neurogenic shock) but of suppressed spinal reflexes below the level of cord injury
- it takes between days and months for spinal shock to completely resolve —> when it does, the flaccidity that was once seen gradually becomes ***spasticity (UMN lesions))

2. Neurogenic shock
   - **Sympathetic signal disruption in C1-T1
   —> Sudden of sympathetic tone
   —> **Vasodilation, Hypotension, Bradycardia, Warm, Flushed skin
   —> Shock, Hypoperfusion of body
   —> Require resuscitation
   - C5 or below: affect Diaphragmatic breathing (Diaphragm innervated by C3-5)
   - Above C3: ***Respiratory arrest (cannot breathe at all)
   —> Require intubation, mechanical ventilation, cardiopulmonary support

Question 20

Causes of Spinal cord injury

Answer 20

By Pathology (VINDICAT):
1. Vascular
2. Infective
3. Neoplastic
4. Degenerative
5. Inflammation
6. Congenital
7. Autoimmune
8. Trauma

Question 21

1. Vascular causes

Answer 21

1. ***Spinal cord infarct (arteries supplying spinal cord occluded)
   - Aortic surgery: EVAR, AAA repair
   - Spontaneous
2. ***Spinal AVM
   - mass effect compression
   - haemorrhage into spinal cord

Question 22

2. Infective causes

Answer 22

1. Spinal ***abscess
2. Meningitis affecting spinal cord
3. TB spine
4. ***Osteomyelitis (e.g. IVDU, DM, HIV)

Question 23

3. Neoplastic causes

Answer 23

Extradural tumour
1. Spinal metastasis
- >90% Vertebral
- Commonly from Breast, Lung, Prostate
- Commonly ***Thoracic spine
- Compress spinal canal + spinal cord within it

Route:
- **Haematogenous spread
- **Direct invasion e.g. Paraspinal lung Ca
- **Lymphatic: along root sleeves
- Subarachnoid seeding via **CSF from primary and secondary CNS neoplasms

Intradural extramedullary tumour
2. Meningioma
- Middle age
- F>M
- Thoracic
- Associated with ***NF-2

3. Schwannoma
   - Cervical + Lumbar
   - NF-2 (multiple schwannoma along spine)
   - ***Radicular pain + **Sensory loss
   - Weakness less common
   - Cord compression if large

Intramedullary tumour
4. Spinal ependymoma
- Commonest **Primary cord tumour in adults
- Male
- NF-2
- WHO grade 2/3 (mostly)
- **Slow growing, discreet, well-circumscribed (can be resected)
- ***Compression (vs infiltrating) the cord

5. Spinal astrocytoma
   - 2nd most common **Primary cord tumour
   - Children (60% lesions)
   - Lower grade lesions than in brain
   - Faster growing than ependymoma
   - **Infiltrative —> Complete excision less likely

Question 24

Treatment for Spinal tumours

Answer 24

1. Surgical resection within safety limit
   - Intraoperative monitoring
   - Motor evoked potential (MEP) and Somatosensory evoked potential (SSEP)
   —> guide extent of surgery + preserve normal neurological function
2. Adjuvant therapy for some
   - External beam radiation therapy (***ERT)
3. Metastasis
   - Primarily ERT
   - Surgery for pain, instability, lesions resistant to RT —> Palliative in nature

Question 25

4. Degenerative causes

Answer 25

Spondylosis
- **Disc degeneration / prolapse —> Compression
- Apophyseal (Facet) joint damage / hypertrophy —> Instability, **Spondylolisthesis —> Narrow spinal canal —> Compression

***Ossified / Hypertrophied Spinal ligaments —> Compression

Question 26

Spondylitis vs Spondylosis vs Spondylolisthesis vs Spondylolysis

Answer 26

Spondylitis:
Vertebral inflammation

Spondylosis:
Vertebral degeneration

Spondylolisthesis:
Vertebral slippage

Spondylolysis:
Anatomic defect or break of the pars interarticularis of the vertebral arch

Question 27

5. Inflammation causes

Answer 27

• **Transverse myelitis
• caused by ***Multiple sclerosis / other causes
• **↑ CSF protein, **CSF pleocytosis, MRI hyperintense area

Question 28

Spondylosis and Myelopathy

Answer 28

• Signs of cervical myelopathy
• Cord compression
• Complete / Incomplete cord damage
• Chronic progressive / Acute exacerbation (e.g. trauma)

Treatment:
1. Conservative management (mild symptoms / no neurological deficits)
- Analgesia
- Physiotherapy

2. Surgical decompression
   - **Progressive neurological deficit
   - **Myelopathy / Radiculopathy
   - Intractable pain

Question 29

6. Congenital causes

Answer 29

Spinal dysraphism (neural tube defect: cannot close completely)
1. **Myelomeningocele (Spinal cord + Nerve root + Meninges protrude out of spinal canal)
2. **Meningocele (Only Meninges protrude)
3. **Spina bifida occulta
—> Conus + Filum terminale can be affected by malformation (e.g. Lipoma formation)
—> Traction in spinal cord
—> **Tethering syndrome

Question 30

Tethered cord syndrome

Answer 30

• Common in Spina bifida occulta
• Anchoring of lower end of spinal cord by:
  —> **Lipoma
  —> **Fatty filum terminale
• ***Low-lying Conus medullaris (at L3/4, normally rise up to L1 level)
• Cord under tension as spine lengthens
  —> Progressive neurological deficit
  —> **Lower limb LMN weakness + **Sphincter dysfunction + Pain + Scoliosis + Foot deformity

Clinical presentation:
- Deterioration at growth spurt (***<2/3 yo or puberty)

Investigation:
- Early detection with MRI
- Urodynamic study

Treatment:
- Surgical untethering before clinical deterioration

Question 31

8. Trauma causes

Answer 31

1. Road traffic accident
2. Fall
3. Assault
4. Sports / Recreation related injury
5. Others

• 50% ***Cervical spine (∵ most mobile + weakest)
• 25% associated with other organ injuries (e.g. head)
• 15% associated with non-adjacent level injuries

Question 32

Spinal trauma classification

Answer 32

According to different pattern of force
1. Vertical compression (e.g. load fall onto head)
- watch out for cord impingement e.g. ∵ **retropulsion of vertebral body fragment compressing **anterior cord

2. Hinge injury (e.g. blow to head)
   - Ligament intact / disrupted
3. Shearing injury (e.g. fall from height)

According to stable / unstable
Stable:
- Vertical compression
- Hinge injury with intact ligament

Unstable:
- Shearing injury
- Hinge injury with disrupted ligament (need early fixation of spine)

Question 33

Other injury causes

Answer 33

Epidural haematoma
- compressing on spinal cord

Question 34

Prognosis of Spinal cord injury

Answer 34

Complete injury:
- Poor
- Recovery rare

Incomplete injury:
- Difficult to predict
- Most recovery occur within ***6 months
- Depending on level and extent of injury
- Many can eventually walk (with aids)

Question 35

Other complications associated with Spinal cord injury

Answer 35

1. ***Limb spasticity
   - can be painful
2. Pressure sore
3. ***Neurogenic bladder
   - Repeated episodes of UTI
   - Reflux nephropathy
4. ***Anal function
   - Constipation
5. ***Sexual function
6. **Autonomic dysreflexia
   - Autonomic dysfunction e.g. **sudden sympathetic storm —> high BP, Temperature, Tachycardia, Sweating
7. ***Temperature control
   - Impaired homeostasis

Question 36

Summary

Answer 36

• Acute paraplegia is an Emergency!
• Where is the lesion —> Anatomy (Dermatome, Myotome, Ascending / Descending tracts, Central / Anterior / Posterior cord)
• What is the lesion —> VINDICATE
• Spinal cord is unforgiving
  —> Significant disability
  —> Complete injury / with Sphincter function loss —> Very poor prognosis