MSS23 Introduction To Spinal Cord Nerve Compression Disorders Flashcards
Cauda equina (horse tail)
Lumbar nerve root (usually starts from L2)
Claudication
**Impairment in walking, or pain, discomfort, numbness, or tiredness in the legs that occurs during walking or standing and is **relieved by rest
Sciatica
Clinical symptom:
Pain going down the leg from the lower back
Radiculopathy
- Dysfunction of single nerve root / pinched nerve (usually Lumbar)
- Lower motor neuron lesion
Myelopathy
- Dysfunction of spinal cord (Cervical / Thoracic)
- Upper motor neuron lesion
History taking
- Pain
- character
- aggravating / relieving factors
- location
- severity - Numbness
- sensory fibres of nerve roots / spinal cord - Weakness
- motor fibres / spinal cord - Balance
- proprioception, severe weakness - Sphincter control
- bowel / bladder
Pathoanatomy of lumbar disc herniation
Stages:
- Protrusion
- Prolapse (nucleus pulposus 就出)
- Extrusion (nucleus pulposus 出左)
- Sequestration (separated / 隔離)
Anatomy of vertebral column
3 levels of vertebra:
- Pedicle (最高)
- Intermediate / Foramen (intervertebral: where nerve root exits)
- Disc (最低: ∴ compression on cord only leads to symptoms of lower levels since nerve root already exited)
3 section (left to right):
- Extraforaminal
- Foraminal
- Lateral recess (compression on lower level traversing nerve root)
- Central
***Causes of Lumbar spinal stenosis
- Dural sac and nerve root compression
- IV disc herniation
- Osteophytes
- Facet joint hypertrophy
- Ligamentum flavum hypertrophy
Spinal cord vs Nerve root
Spinal cord: CNS (usual injury site: Cervical and Thoracic region)
Nerve root: Initial segment of nerve which leaves the CNS (i.e. PNS) (usual injury site: Lumbar region)
(Surgery to decompress lumbar spine)
- Enter through central region
- Excise ligamentum flavum
- Retract nerve root
- Take out intervertebral disc fragments
Cervical spine anatomy
5 articulations between adjacent cervical vertebrae:
- IV disk
- 2 Facet joints
- 2 Uncovertebral joint (兜 in body)
Borders of intervertebral foramina:
- Superior: pedicle of vertebra above
- Inferior: pedicle of vertebra below
- Posterolaterally: facet joint
- Antermedially: uncovertebral joint, IV disk
- 7 cervical vertebra
- 8 cervical nerve roots
Unlike Lumbar / Thoracic region:
- Cervical nerve root exits above its vertebra:
- -> C1 root exits above C1
- -> C8 root exits between C7/T1
Cervical radiculopathy
- Root irritation
- ***Dermatomal
- Sharp pain + Tingling / burning sensation
Cervical myelopathy
- Cord dysfunction
Causes:
- Protruding disk
- Osteophyte
- OPLL (Ossification of the Posterior Longitudinal Ligament)
- Deformed uncovertebral process
- Facet joint dislocation (can lead to serious cord injury –> tetraplegia)
- Ligamentum flavum problem
(Surgery to decompress cervical spine)
- go through neck muscle e.g. SCM
- go through deep cervical fascia (between SCM and strap muscle)
- surrounding structures: carotid sheath, trachea, esophagus
- expose prevertebral fascia and longus colli muscle
- decompress / remove IV disk
- tricortical graft to stabilize IV region
***Descending vs Ascending Tracts
Descending tract (Motor)
- Lateral corticospinal tract
- main voluntary motor
- upper extremity motor
- pathways more medial/central
- 最出–>最入: control Sacral –> Lumbar –> Thoracic –> Cervical - Ventral corticospinal tract
- voluntary motor
Ascending tract (Sensory)
- Dorsal columns (posterior funiculi)
- deep touch
- proprioception
- vibratory - Lateral spinothalamic tract
- pain
- temperature
(3. Ventral spinothalamic tract)
- light touch
Central cord syndrome
Etiologies:
- **1. Trauma (esp. with cervical arthritis, older patients worse prognosis)
2. Spondylotic myelopathy
3. Syringomyelia (cyst within cord)
4. Neoplasm: metastatic, glial, lymphoma
Symptoms:
- Sensory loss
- loss in pain, temperature > posterior column sensation
* **2. Weakness: Arms worse than Legs (since cervical pathways more medial in LCT) - May occur in absence of spinal fracture
Brown-Sequard: Hemicord (one side of cord) injury
Etiologies:
- **1. Penetrating trauma
2. Radiation - **3. Decompression sickness
4. Multiple sclerosis
Symptoms:
- Ipsilateral loss
- weakness
- position sense - Contralateral loss
- pain, temperature
- rarely typical
Prognosis:
- 75-90% ambulate on discharge
- 70% independent ADL
- 80% bladder, bowel continent
Arterial supply to vertebral column
- ***Segmental arteries from vertebral, intercostal, lumbar arteries
- -> anastomosing spinal branches
- Rich supply of vessels in region of vertebral end plates (transition region between body and IV disc)
(- vessels do not penetrate cartilaginous end plate even in infancy
- IV disc: Avascular, obtain nutrient by diffusion from tissue fluid)
Blood supply to spinal column
- 1x **Anterior spinal artery
- supply Whole cord anterior to posterior grey column
- formed by union of 2 spinal arteries (from **Vertebral artery) at foramen magnum
- Midline vessel lies on ***Anterior median fissure
- run length of cord (become small / absent in thoracic region) - 2x **Posterior spinal artery
- supply Grey + White posterior column
- arise from **Posterior inferior cerebellar artery / ***Vertebral artery above foramen magnum
- descend from level of foramen magnum –> form 3 longitudinal channels
- run through and behind posterior rootlets for length of cord
- some anastomoses between 2 vessels -
**Radicular arteries
- Most characteristic feature:
- -> Variability in no., position
- -> blood may flow up/down the cord
- largest: **Artery of Adamkiewicz: usually arise from left T10 (T5-L5)
- highly important contribution to reinforce longitudinal trunks
- most disappear as fetus grow
- remaining anastomise with anterior/posterior spinal arteries
- supplemented at variable levels by anastomoses with variable no. of radicular arteries
Anterior cord syndrome
Etiology:
- deep, difficult to damage
1. Ischaemia of anterior spinal artery (territory)
2. Fracture fragments
3. Retro-pulsed disc
Symptoms:
- Loss of ***motor function
- Loss of pain sensation
- Loss of temperature sensation
- Position sense preserved
Prognosis:
- 10-20% muscle recovery
- poor muscle power and coordination
Posterior cord syndrome (least common)
Etiology:
- Damage of posterior spinal artery
- Diffuse artherosclerosis (deficient collateral perfusion)
- B12 deficiency
Symptoms:
- Loss of ***position sense
- Motor, pain, temperature preserved
Prognosis:
- better than anterior syndrome
- poor ambulation prospect due to proprioceptive deficit
Venous drainage of vertebral column
***Spinal venous plexus
Significance:
- **Batson’s plexus:
- Pelvis venous drainage communicate with Spinal venous plexus
- Pelvic tumours and infections –> spread to spinal column
Pathology of vertebral column
Blood borne infection (starts in vertebral end plate)
- -> suppurative inflammation
- -> ***bone necrosis, collapse
- -> spread to adjacent IV disc + vertebra
- -> ***paravertebral abscess
- -> ***epidural abscess
- -> infection of meninges, spinal cord
- -> occasionally involve posterior elements
Pyogenic spondylitis (broad term)
focus of Osteomyelitis in vertebral body
- -> spread into IV disc by perforating end plate
- -> spread in disc and adjacent vertebral body
- -> **destruction of disc + **narrowing of IV space
TB spine features
- Multiple levels
- More bony involvement
- Subligamentous spread
- ***Skip lesions
Spinal metastasis
Mechanism (Venous system):
1. Breast via azygous system
2. Lung via pulmonary vein and arterial system
3. **Prostate via pelvic plexus
- **Batson’s plexus: connection between peri-prostatic plexus and vertebral venous plexus
—> network of longitudinal valveless veins that anastomose with the vertebral marrow and epidural venous channels
—> ↑ intra-abdominal pressure —> divert blood into the epidural venous plexus —> pathway of metastatic embolization
Pathway of local spread:
- Venous sinusoids of vertebral body
—> Barriers to local spread: ALL, PLL, Ligamentum flavum, Periosteum, endplates, annulus
—> Tumour cells invade at sites of vascular perforations in barriers
Diagnosis:
Plain radiographs
- **destruction not evident until 30-50% spongy bone destroyed
- **Winking owl sign classic (Absence of pedicle on radiograph, normally can see pedicle)
