Prolapsed Intervertebral Disc (PID) - Lumbar
Lumbar Disc Herniation is the leading cause of sciatica. It occurs when the gelatinous nucleus pulposus breaks through the fibrous annulus fibrosus, compressing nerve roots.
[Image of Lumbar Disc Herniation Stages]1. Stages of Herniation
- Bulge: Generalized extension of disc border (annulus intact).
- Protrusion: Focal bulge, annulus intact but thin.
- Extrusion: Nucleus breaks through annulus but stays connected.
- Sequestration: Free fragment usually in the spinal canal (Chemical radiculitis).
2. Anatomy of Nerve Compression
In the lumbar spine, a posterolateral disc herniation usually affects the traversing nerve root (the lower one).
- L4-L5 Disc: Compresses L5 Nerve Root. (Weak Extensor Hallucis Longus - Big toe extension).
- L5-S1 Disc: Compresses S1 Nerve Root. (Weak Plantarflexion, Loss of Ankle Jerk).
3. Clinical Tests
- SLRT (Straight Leg Raise): Pain between 30-70 degrees suggests root tension.
- Lasegue Sign: Lower leg 5 degrees from pain point, dorsiflex foot. (+ve if pain returns).
- Crossed SLRT: Lifting the good leg causes pain in the bad leg. (Highly specific for herniation).
4. Management
- Conservative (90%): Rest (brief), NSAIDs, Physiotherapy (McKenzie extension, Core stabilization).
- Surgery: Microdiscectomy. Indicated for Cauda Equina Syndrome (Emergency), progressive motor deficit, or intractable pain > 6 weeks.
25 Practice MCQs
Q1. Most common site for lumbar disc herniation is:
Answer: A). Accounts for 95% of cases due to high mobility/load.
Q2. A posterolateral herniation at L4-L5 usually compresses:
Answer: B). L4 exits above the disc; L5 passes behind it.
Q3. Cauda Equina Syndrome presents with:
Answer: A). Surgical emergency requiring decompression within 48 hours.
Q4. S1 nerve root compression leads to weakness in:
Answer: A). Also loss of Ankle Jerk reflex.
Q5. L5 nerve root compression causes:
Answer: A). Numbness is on the dorsum of foot/web space.
Q6. SLRT is considered positive for disc herniation if pain occurs at:
Answer: A). <30 is hip issue, >70 is hamstring/SI joint.
Q7. Crossed SLRT (Well Leg Raising Test) is highly specific for:
Answer: A). Lifting the good leg pulls the dural sac and irritates the bad side.
Q8. Which position increases intradiscal pressure the most?
Answer: A). Flexion + Load is bad for discs.
Q9. Sequestration means:
Answer: A). Nucleus material is highly inflammatory to nerves.
Q10. McKenzie extension exercises are used because:
Answer: A). If pain moves from leg to back (centralizes), it's a good sign.
Q11. Far Lateral (Foraminal) Herniation at L4-L5 affects:
Answer: A). Exception to the rule. It hits the root in the foramen.
Q12. Spontaneous regression of disc herniation:
Answer: A). The body attacks the extruded material.
Q13. Femoral Nerve Stretch Test is positive in:
Answer: A). Pain in anterior thigh upon knee flexion in prone position.
Q14. Microdiscectomy success rate for leg pain is:
Answer: A). Surgery is better for Radiculopathy (Leg) than Axial (Back) pain.
Q15. The "Slump Test" is used for:
Answer: A). More sensitive than SLRT.
Q16. L4 nerve root compression affects which reflex?
Answer: A). L4 innervates Quadriceps.
Q17. Bed rest for sciatica should be:
Answer: A). Prolonged rest leads to deconditioning and chronic pain.
Q18. Modic changes on MRI represent:
Answer: A). Type 1 (Inflammation), Type 2 (Fatty), Type 3 (Sclerosis).
Q19. Schmorl's Node is:
Answer: A). Usually asymptomatic.
Q20. Functional Scoliosis in PID is:
Answer: A). Patient leans away from the pain (usually).
Q21. Facet Joint Tropism is:
Answer: A). Predisposes to rotational stress and herniation.
Q22. Bowstring Sign involves:
Answer: A). Compresses the sciatic nerve directly.
Q23. Is MRI necessary for everyone with back pain?
Answer: B). Many asymptomatic people have bulges. Treat the patient, not the MRI.
Q24. Spondylodiscitis refers to:
Answer: A). A red flag condition.
Q25. Waddell's Signs test for:
Answer: A). e.g., Overreaction, Distraction, Regional disturbances.
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