Focused examination for lumbar disc herniation including straight leg raise, crossed straight leg raise, femoral stretch testing, and differentiation of L4, L5, and S1 radiculopathy.
Lumbar disc herniation examination requires systematic neurological assessment and provocative testing. Examiners expect you to perform the straight leg raise correctly, recognize the difference between L4, L5, and S1 radiculopathy, and always screen for cauda equina syndrome.
High-Yield Exam Summary
Lumbar Root Anatomy:
Disc Herniation Patterns:
Prevalence:
Cauda Equina Syndrome - Surgical Emergency: Screen EVERY patient with lumbar symptoms:
If present → URGENT MRI and neurosurgical referral
Typical Disc Herniation:
Aggravating Factors:
Relieving Factors:
Lumbosacral nerve root tension (L4-S1)
Reproduction of radicular leg pain between 35-70° of hip flexion
Lumbosacral nerve root irritation (L4, L5, S1). Pain must radiate below knee to be significant
Ability to detect true positives
Ability to exclude false positives
SLR Interpretation:
Confirm disc herniation
Pain reproduced in the symptomatic leg when raising the asymptomatic leg
Central or large disc herniation (highly specific for disc herniation)
Ability to detect true positives
Ability to exclude false positives
Confirm neural tension as cause of SLR pain
Reproduction of radicular leg pain with popliteal pressure
Sciatic nerve irritation (confirms neural origin of SLR pain)
Ability to detect true positives
Ability to exclude false positives
Upper lumbar root tension (L2, L3, L4)
Reproduction of anterior thigh pain (radicular pattern)
L2, L3, or L4 nerve root irritation (stretches femoral nerve)
Ability to detect true positives
Ability to exclude false positives
Neural tension (sitting equivalent of SLR)
Reproduction of radicular leg symptoms
Neural tension. May be positive when SLR equivocal
Ability to detect true positives
Ability to exclude false positives
| root | motor | sensory | reflex | discLevel |
|---|---|---|---|---|
| L4 | Knee extension (quadriceps), hip adduction | Medial leg (shin) | Patellar (knee jerk) | L3-4 |
| L5 | Great toe extension (EHL), ankle dorsiflexion, hip abduction | Lateral leg, dorsum of foot, great toe | None reliable (medial hamstring) | L4-5 |
| S1 | Ankle plantarflexion, hip extension, toe flexion | Posterior calf, lateral foot, sole | Ankle jerk (Achilles) | L5-S1 |
Quick Root Differentiation:
Memory Aid:
L4 - Quadriceps (Knee Extension):
L5 - Extensor Hallucis Longus (Great Toe Extension):
S1 - Gastrocnemius/Soleus (Plantarflexion):
Always test in suspected disc herniation:
Saddle Sensation:
Anal Tone:
Bladder Function:
| condition | pain | slr | motor | reflex |
|---|---|---|---|---|
| Disc Herniation | Leg > back, dermatomal | Positive 35-70° | Myotomal weakness | Decreased at level |
| Lumbar Stenosis | Both legs, neurogenic claudication | Usually negative | May be normal | May be decreased |
| Piriformis Syndrome | Buttock to leg | May be positive | Normal | Normal |
| Hip OA | Groin, anterior thigh | Negative | Normal | Normal |
| Spondylolisthesis | Back > leg | Variable | May be affected | Variable |
| Tumor/Infection | Constant, night pain | Variable | May be progressive | Variable |
"38-year-old man with 3-week history of left leg pain radiating to the lateral leg and dorsum of foot, worse with sitting."
| feature | l4 | l5 | s1 |
|---|---|---|---|
| Pain Distribution | Anterior thigh, medial leg | Lateral leg, dorsum foot | Posterior leg, lateral foot |
| Key Motor | Knee extension | Great toe extension | Plantarflexion |
| Functional Test | Squat and rise | Heel walk | Toe walk/single heel raise |
| Reflex | Knee jerk decreased | None reliable | Ankle jerk decreased |
| Disc Level | L3-4 | L4-5 | L5-S1 |
High-Yield Exam Summary