Neurosurgery JC031: Paraplegia: Spinal Cord Compression, Transverse Myelitis, Spinal Dysraphism, Neuroimaging 3: Spinal Cord Flashcards
(36 cards)
Plegia
Weakness of limb
4 types:
1. Monoplegia (one limb)
2. Hemiplegia (half of body)
3. Paraplegia (lower half)
4. Tetraplegia
Revision: Spinal anatomy
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
Motor pathway
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
UMN vs LMN
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
Myotome
***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
Sensation / Ascending tracts
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
Sensory loss
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
Dermatome sensory level
T4: Nipple
T7: Xyphisternum
T10: **Umbilicus
L1: **Groin / Inguinal region
C5-T1: Upper limb
L2-S2: Lower limb
Conus medullaris, Cauda equina
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
Cauda equina syndrome
- **Saddle anaesthesia (loss of sensation of **sacral dermatome (S2-5)
-
**Sphincter dysfunction
- Bladder: Painless acute urinary **retention
- Bowel: ***Constipation
- Irreversible unless very early intervention
Spinal cord blood supply
- 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 - 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 - Posterior spinal artery
- from ***Vertebral artery in brain
- paired
- posterior surface of spinal cord
- anastomose with Anterior spinal artery (circumferentially + inside)
Spinal cord syndromes
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
- Hemi-transection (Brown-Sequard syndrome)
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)
- 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)
- 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) - Ipsilateral loss of ALL sensations ***at the level of lesion due to direct damage to ventral and dorsal grey matter
Horner’s syndrome
Lesion affecting ***Cervical spine, if Sympathetic trunk damaged:
1. Miosis (vs CN3 palsy: Mydriasis)
2. Ptosis
3. Enophthalmos
4. Anhydrosis (↓ sweating)
- Central cord syndrome
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
- 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)
- Anterior cord syndrome
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)
- Posterior cord syndrome
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
Grading severity of injury: American Spinal Injury Association (ASIA) Classification
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
Spinal shock
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))
- 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
Causes of Spinal cord injury
By Pathology (VINDICAT):
1. Vascular
2. Infective
3. Neoplastic
4. Degenerative
5. Inflammation
6. Congenital
7. Autoimmune
8. Trauma
- Vascular causes
- ***Spinal cord infarct (arteries supplying spinal cord occluded)
- Aortic surgery: EVAR, AAA repair
- Spontaneous - ***Spinal AVM
- mass effect compression
- haemorrhage into spinal cord
- Infective causes
- Spinal ***abscess
- Meningitis affecting spinal cord
- TB spine
- ***Osteomyelitis (e.g. IVDU, DM, HIV)
- Neoplastic causes
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
- 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
- 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
Treatment for Spinal tumours
- Surgical resection within safety limit
- Intraoperative monitoring
- Motor evoked potential (MEP) and Somatosensory evoked potential (SSEP)
—> guide extent of surgery + preserve normal neurological function - Adjuvant therapy for some
- External beam radiation therapy (***ERT) - Metastasis
- Primarily ERT
- Surgery for pain, instability, lesions resistant to RT —> Palliative in nature
