Comprehensive lower limb neurological examination including dermatomal and myotomal testing, peripheral nerve assessment, cauda equina screening, and gait analysis.
Lower limb neurological examination is essential for evaluating lumbar spine pathology. Examiners expect systematic testing of key myotomes (L2-S1), dermatomes, reflexes, and identification of red flags for cauda equina syndrome. Always include gait assessment.
High-Yield Exam Summary
Components:
Key Principle: The lower limb examination must include cauda equina screening in any patient with lumbar symptoms.
Normal Gait Phases:
Abnormal Patterns:
Foot Drop Gait (L5/Peroneal):
Trendelenburg Gait (L5/Hip Abductors):
Antalgic Gait:
Spastic Gait (UMN):
Test L4-L5 (ankle dorsiflexors)
Inability to maintain heel walking
L4-L5 weakness (tibialis anterior, EHL)
Ability to detect true positives
Ability to exclude false positives
Test S1-S2 (ankle plantarflexors)
Inability to maintain toe walking or asymmetry
S1-S2 weakness (gastrocnemius, soleus)
Ability to detect true positives
Ability to exclude false positives
Look For:
Key Areas:
| root | movement | muscle | position | instruction |
|---|---|---|---|---|
| L2 | Hip flexion | Iliopsoas | Sitting | Lift thigh off bed against my hand |
| L3 | Knee extension | Quadriceps | Sitting | Straighten knee against my resistance |
| L4 | Ankle dorsiflexion | Tibialis anterior | Supine | Pull foot up toward you |
| L5 | Great toe extension | EHL | Supine | Pull big toe up against my finger |
| S1 | Ankle plantarflexion | Gastrocnemius | Supine/standing | Push foot down (or single heel raise) |
| S1 | Ankle eversion | Peronei | Supine | Turn foot outward against resistance |
Key Root Level Tests:
Common Disc Levels:
Key Testing Points:
Testing Technique:
Critical for Cauda Equina:
Testing:
Red Flag: Reduced perianal sensation = suspected cauda equina until proven otherwise.
Test L3-L4 nerve roots
Absent or diminished = L3-4 radiculopathy; Increased = UMN lesion
L3-L4 reflex arc integrity
Ability to detect true positives
Ability to exclude false positives
Test S1-S2 nerve roots
Absent or diminished = S1 radiculopathy; Increased = UMN lesion
S1-S2 reflex arc integrity
Ability to detect true positives
Ability to exclude false positives
Test for upper motor neuron lesion
Extension (dorsiflexion) of great toe ± fanning of other toes
Upper motor neuron lesion (corticospinal tract dysfunction)
Ability to detect true positives
Ability to exclude false positives
When Reflex Appears Absent:
Interpretation:
Detect L5-S1 root irritation
Radicular pain (below knee) at less than 70°
L4, L5, or S1 nerve root irritation (usually disc herniation)
Ability to detect true positives
Ability to exclude false positives
Detect large disc herniation
Pain in affected leg when raising unaffected leg
Large, axillary disc herniation with significant nerve root compression
Ability to detect true positives
Ability to exclude false positives
Detect L2-L4 root irritation
Pain in anterior thigh (femoral nerve distribution)
Upper lumbar (L2, L3, L4) nerve root irritation
Ability to detect true positives
Ability to exclude false positives
Cauda Equina Red Flags - MUST ASK:
If ANY present: URGENT MRI and surgical assessment
Sensory:
Motor:
Reflexes:
Post-void Residual:
L4 Radiculopathy:
Common Cause: L3-4 disc herniation
| root | slr | femoralStretch | kneeJerk | ankleJerk | motor |
|---|---|---|---|---|---|
| L4 | May be positive | Positive | Reduced | Normal | Ankle DF, knee extension |
| L5 | Positive | Negative | Normal | Normal | EHL, ankle DF, hip abduction |
| S1 | Positive | Negative | Normal | Reduced | Ankle PF, eversion |
| feature | lmn | umn |
|---|---|---|
| Tone | Reduced (flaccid) | Increased (spastic) |
| Power | Weakness in specific myotome | Pyramidal pattern weakness |
| Reflexes | Reduced or absent | Increased (hyperreflexia) |
| Clonus | Absent | May be present |
| Babinski | Flexor (normal) | Extensor (upgoing) |
| Wasting | Present | Late/minimal |
| Fasciculations | May be present | Absent |
"45-year-old man with right leg pain radiating from buttock to foot, worse on coughing."
High-Yield Exam Summary