IVD PATHO Flashcards
Discopathy: def, composition & components
= degeneration of IVD
→ Inner gelatinous nucleus pulposus
- Type II collagen : resistant to compression
→ Outer annulus fibrosus
- Type I collagen : resistant to tensile strength
→ Cartilage end plates (sup & inf) - Nutrition : glucose, oxygen, …
Proteoglycan & collagen = skeletal structure of disc - Aggrecan : most common proteoglycan in disc
* 70% of nucleus pulposus
* 25% of annulus fibrosus
High concentration of aggrecan
- Enable tissue to support compressive load
- Loads transferred equally to annulus fibrosus & vertebral boby
Chondrocytes:
- synthesize matrix : proteoglycan & collagen
- Break down matrix : Matrix Metalloproteinase (MMPs)
Turnover maintained at highest level in adolescence - Decrease progressively with time
Injured disc : higher concentration of catabolic cytokines & MMPs
- Healing process overtaken by degenerative changes
DISCOPATHY: factors, consequences & features
- genetics, nutrition, smoking, cell senescence, degraded matrix product, fatigue failure of nucleus, heavy load
- loss of viscoelasticity , hydrophilicity, hydrostatic pressure of nucleus pulposus, supply of nutrients by diffusion , disk height because decreased water content, resistant to axial load, no longer fct hydrostatically under load
- stress load along end plate & annuls = annular bulge
Loss of height alters mechanics of facet joints: osteophytes at disc margins, at facet joints margin, periarticular fibrosis, buckling of ligament flavum
DISCOPATHY: symptoms, cells & fcts
- Degenerative disk ≠ symptoms
- Most important causes of degeneration: impairing its healing response
- Age-specific prevalence estimates of degenerative spine imaging findings in asymptomatic patients
- disk degeneration, signal loss, height loss, bulge, protrusion, annular fissure, facet degeneration, spondylolisthesis
Neurotransmitters promotes peripheral sensitization - Substance P
- Calcitonin generated peptide
Mast cells: Promotes inflammation, Neovascularization, Neoinnvervation
Low pH stimulates neurogenic (& non-neurogenic) pain: Phospholipase 2
* Intraneural oedema
* Demyelination
* Axonal injury
Spontaneous regression: Bulging : 13%, Protrusion : 41%, Extrusion : 79%, Sequestration : 96%
Complete resolution: Sequestration : 43% & Extruded : 15%
Timeframe: 3 months to 1 year
DISC HERNIATION: ≠ steps & definition of each, % of spontaneous resorption
Bulging = extension of disc margin behind margins of adjacent vertebral end plates
Protrusion = posterior longitudinal ligament remains intact but nucleus pulposus impinges on anulus fibrosus
Extrusion = nuclear material emerges through annular fibers but posterior longitudinal ligament remains intact
Sequestration = nuclear material emerges through annular fibers & posterior longitudinal ligament disrupted. Portion of nucleus pulposus protruded into epidural space
=> 67% of spontaneous resorption
FEATURES OF STENOSIS
Mainly cervical (CSS) or lumbar (LSS)
- Congenital
* LSS associated with CSS (10%)
- Acquired
* Degenerative arthritis
* Degenerative flava ligament * Spondylolisthesis
- 3 joints complex
* Disc – intervertebral bodies – facet joints
- Location:
* L3-L4-L5
*L5-S1 anatomically wider
- Stenosis: Central, Lateral, Foraminal
FLAVA LIGAMENT & DEGENERATION
- 80% of elastic fibers: prevent buckling - 20% of collagen
DEGENERATION - Hypertrophic scar formation * Repeated inflammation
- Ossification over time
- Genetic component (e.g. Asian)
- Elastic fibers being replaced by collagen * Leads to buckling
SPINAL STENOSIS: translation & classification
Translation of one vertebra over caudal one - Anterolisthesis
- Retrolisthesis
- Usually preceded by spondylolysis
* Fracture of pars articularis
Classification
- Dysplasic (congenital)
- Isthmic
- Degenerative
- Traumatic
- Iatrogenic
RADICULOPATHY: def, causes, pathophysio
= range of symptoms produced by pinching of nerve root in spinal column
- Herniated disc
- Degenerative spine component
- Degenerative change in disc
- Hypertrophy of ligamentum flavum * Osteophyte formation
- Nerve root distortion
- Intraneural oedema
- Localized inflammatory response (chemical pain mediator within disc)
- Focal nerve ischemia (impaired circulation)
SCHÉMA
MYOTOMES
Motor weakness
- C1/C2 : Cervical flexion
- C3 : Cervical lateral flexion - C4 : Scapula elevation
- C5 : shoulder Abduction
- C6 : Elbow flexion
- C7 : Elbow extension
- C8 : Thumb extension
- T1 : Finger Abduction
- L1/L2 : Hip flexion
- L3 : Knee extension
- L4 : Ankle dorsiflexion
- L5 : Big toe extension
- S1 : Ankle plantar flexion
- S2 : knee flexion
DERMATOMES + grading
Deep Tendon reflexes - C5/C6 : Biceps
- C6 : Brachioradialis - C7 : Triceps
- L4 : Patellar
- L5/S1 : Achilles
0 = no response; always abnormal
1+ = slight but definitely present response; normal or not
2+ = brisk response; normal
3+ = very brisk response; normal or not
4+ = tap elicits repeating reflex (clonus); always abnormal
5+ = sustained clonus; always abnormal
RADICULOPATHY: pressure & ischemia
- pTunnel < pVein < pFasciculus < pCapillaries < pArtery
- 20-30mmHg disrupts intraneural venous circulation
- 40-50mmHg suppress arteriolar & capillary blood flow Herniated disc : 50 – 250mmHg
- Position-dependent paraesthesia - Demyelination
- Slowing of nerve conduction
- Influx of inflammatory cells
- Elevation of osmolality = Œdema
- Intraneural & extraneural fibrosis * Impaired gliding abilities
Affects both large & small diameter nerve fibers
≠ between Lx & Cx spine
Nerve root mismatch
Cx: C6 nerve root travels under C5 pedicle = mismatch
Lx: L5 nerve root travels under L5 pedicle = match
Extra C8: nerve root allows transition => no pedicle
- ≠ nerve roots affected depending on location of compression * Central
- Posterolateral
- Foraminal
- Because of vertical anatomy of lumbar nerve root paracentral & foraminal disc herniation affect ≠ nerve roots
- Because of horizontal anatomy of cervical nerve root central & foraminal disc herniation affect same nerve root
RADICULOPATHY : TABLEAU
Tableau
SCHEUERMANN’S DISEASE: def, features, etiology, prevalence,
D: developmental disorder = juvenile osteochondrosis
F: Thoracic vertebral wedge > 5° in 3 or more adjacent vertebrae
* 45° < Thoracic kyphosis < 75°
* Structural deformity
E: multifactorial: genetics, juvenile osteochondrosis…
P: in Europe 8% > 50y
ANKYLOSING SPONDYLITIS (BECHTEREW): def, causes, prevalence, diagnosis & clinical presentation
D: type of arthritis that causes inflammation in the joints and ligaments of the spine
C: unknown but often environmental factors & genetic
P: 0.1 – 1.8% / Onset < 35 years / Male > Female (3/1)
D: based on symptoms, medical imaging & blood test
CP: - Affects sacroiliac, zygapoohyseal & costovertebral joints
- Pain in heels, ischial tuberosity, iliac crests, humeral epicondyles & shoulders
- Noctural pain
- Morning pain & stiffness
- Asymmetric peripheral arthritis
- Uveitis with pain & photophobia
