366.2 🩺 國考版

366.2.1 高頻考點

366.2.1.1 Red Flags

  • Cancer: age > 50, history, weight loss, night pain
  • Infection: fever, IVDU, immunosuppression
  • Fracture: trauma, steroids, osteoporosis
  • Cauda equina: saddle anesthesia, urinary retention, bilateral leg, bowel — EMERGENCY
  • Cord compression: UMN signs

366.2.1.2 Imaging

  • No imaging acute LBP < 6 weeks no red flags
  • MRI if red flags or persistent

366.2.1.3 Nerve Root Patterns

Lumbar: - L4: anterior/medial thigh; knee jerk; quad weakness - L5: lateral leg, dorsum foot; foot drop; great toe extension - S1: posterior leg, lateral foot; plantarflexion; ankle jerk

Cervical: - C5: deltoid, biceps; biceps reflex - C6: biceps, brachioradialis reflex; thumb - C7: triceps reflex; middle finger - C8: hand intrinsics; little finger

366.2.1.4 Cauda Equina Triad

  • Saddle anesthesia
  • Urinary retention (most sensitive)
  • Bilateral leg weakness/numbness
  • Bowel/bladder dysfunction
  • Decreased rectal tone

Action: urgent MRI + neurosurgery; decompress within 48 hr

366.2.1.5 Spinal Stenosis

  • Older
  • Bilateral leg pain with walking
  • Relief by flexion (shopping cart)
  • Pulses normal (vs vascular)
  • MRI confirms

366.2.1.6 Spinal Epidural Abscess

  • IVDU, immunosuppression
  • Back pain + fever + neuro
  • ↑ ESR, CRP, WBC
  • MRI gadolinium
  • Drainage + antibiotics

366.2.1.7 Disc Herniation

  • L5-S1 or L4-L5 most common
  • Acute or recurrent
  • Sciatica
  • SLR positive
  • Most resolve in 6-12 weeks

366.2.1.8 Ankylosing Spondylitis Features

  • Young (< 45)
  • Inflammatory pain (morning stiffness, exercise improves)
  • Bilateral sacroiliitis
  • HLA-B27
  • Bamboo spine

366.2.1.9 Treatment Sequence

  1. Stay active + NSAIDs + PT
  2. Muscle relaxants short-term
  3. Persistent → epidural steroid (radicular)
  4. Surgery if cauda equina, progressive deficit, or refractory > 6 weeks

366.2.2 Distinguishing Features

366.2.2.1 Mechanical vs Inflammatory Back Pain

Feature Mechanical Inflammatory (SpA)
Onset Any age < 45
Morning stiffness < 30 min > 30 min
Pain at rest No Yes
Improved by Rest Exercise
Worse by Activity Rest

366.2.2.2 Neurogenic vs Vascular Claudication

Feature Neurogenic Vascular
Pulses Normal Decreased
Onset Walking, standing Walking only
Relief by Flexion (sitting) Standing still
Walking distance Variable Fixed