Discogenic Flashcards
(17 cards)
Structure of Intervertebral Discs
- Made of annulus fibrosus (dense collagen ring) and nucleus pulposus (gel-like centre).
- Act as fibrocartilaginous shock absorbers.
- Fluid-filled nucleus allows flexibility and load distribution.
- Herniation occurs when nucleus protrudes through weakened annulus—typically posterolaterally (weaker, lacks ligament support).
Pathophysiological Mechanism
- Degeneration reduces disc hydration and elasticity → nucleus bulges or herniates.
- Herniations cause symptoms by:
o Mechanical compression of spinal nerve roots.
o Chemical irritation from inflammatory mediators.
4 types
Bulge
Protrusion
Extrusion
Sequestration
Disc bulge
Mild disc deformation.
11.1% complete resolution rate - rarely resolves fully. Often stable or chronic.
Protrusion
Disc pushes out but nucleus is still contained.
0% complete resolution rate - least likely to resolve spontaniously.
Extrusion
Nucleus pulposus breaks through annulus but stays attached. 15% - better potential to shrink due to immune response.
Sequestration
Fragment completely separated from disc. 43% - highest rate of full resolution. Body often reabsorbs free fragment.
What stage has the best prognosis
- High-grade herniations (extrusion, sequestration) are more likely to regress due to immune recognition.
- Lower grade (bulge/protrusion) often persist.
Prevalence
- 1–3% of LBP cases involve symptomatic herniation.
- Peak incidence: ages 30–50 (disc still hydrated).
- Most herniations occur at L4/5 (50%) and L5/S1 (40%).
How does location change as you age
Over 65 Only 40% at L4/5 or L5/S1; most at L1/2–L3/4. Upper lumbar herniations due to degeneration, reduced mobility at lower levels.
Mean age by level:
o L5/S1: 44.1 years
o L4/5: 49.5 years
o L3/4: 59.5 years
o L2/3: 59.6 years
Risk factors
- Repetitive stress, poor posture, asymmetrical loading.
- Weak core, tight hamstrings, lower cross syndrome.
- Trauma (lifting, twisting), congenital issues, poor general health.
Symptoms
- Sudden onset LBP, often radiating below the knee (sciatica).
- Pain described as sharp, shooting, electric—dermatomal.
- Worse with flexion, sitting, Valsalva; relieved by extension, lying down.
- May follow inciting event: lifting, twisting, etc.
- Waking up in the middle of the night: During the day, gravity and activity cause spinal discs to lose some water content, slightly decreasing their height and pressure.
- At night, lying down reduces this axial load, allowing discs to rehydrate and swell slightly. This increase in disc volume may:
- Raise intradiscal pressure
- Aggravate nerve endings in the annulus fibrosus or outer disc
- Increase chemical irritation from inflammatory mediators
Nerve root specifics
- L5: Buttock → lateral leg → dorsum of foot; weakness in dorsiflexion, toe extension.
- S1: Posterior thigh → calf → lateral/plantar foot; weakness in plantar flexion; possible incontinence.
Diagnosis
SLR positive between 35–70°.
MRI: only after ≥6 weeks of symptoms unless red flags (severe/rising neuro)
Acute management
- Bed rest max 2–3 days; early mobilization (e.g., walk 20 min every 3 hrs).
- NSAIDs, analgesics, hot/cold compress, traction.
Walk, swim, walk in water
Minimise sitting, bending, twisting
Physical therapy
- Start after 3 weeks of symptoms.
Foraminal gap, soft tissue to desensitise
Release pressure – what do you find comfy – do that instead – tv at night lie down in order to release pressure in order for it to heal
Sit with back support – cushion
- Tailor exercises to directional preference:
o Extension bias (centralization) → McKenzie exercises.
o Flexion bias (less common) → Williams flexion. - Lumbar stabilization protocols: core strengthening, neutral pelvis.
Prognosis
- ~90% improve in 6 weeks; 75% resolve in 6 months.
- 60–90% respond well to conservative care.
- Most regression occurs early—within months.
