366.3 🏥 內科專科考前版

366.3.1 Mechanistic Deep Dive

366.3.1.1 Disc Anatomy

  • Annulus fibrosus (outer)
  • Nucleus pulposus (inner)
  • Herniation: nucleus pushes through annulus
  • Compresses adjacent nerve root

366.3.1.2 Spinal Stenosis Pathophysiology

  • Degenerative
  • Hypertrophy of facets, ligamentum flavum
  • Disc bulge
  • ↓ space for cauda equina
  • Worse with extension (standing/walking)
  • Better with flexion (sitting/leaning)

366.3.1.3 Cauda Equina Pathophysiology

  • Compression of L1-S5 nerve roots
  • Vs conus medullaris (T12-L1 cord end)
  • Causes: massive central disc, tumor, hematoma, abscess, trauma

366.3.1.4 Neurogenic Claudication

  • Vascular compromise of nerve roots
  • Worsened by ↓ space (extension)
  • Improved by ↑ space (flexion)

366.3.2 Recent Trials & Updates

366.3.2.1 Suzetrigine for Acute Pain

  • NaV1.8 inhibitor
  • FDA 2025
  • May reduce opioid use post-surgery
  • Trials in acute pain include surgical pain

366.3.2.2 Stem Cell Therapy for Discogenic Pain

  • Limited evidence
  • Experimental
  • Disc regeneration

366.3.2.3 CGRP for Chronic Low Back Pain

  • Trials underway
  • Limited evidence so far

366.3.2.4 Anti-NGF (Tanezumab)

  • Promising for chronic LBP
  • Joint safety concerns (RPOA)
  • Not FDA approved (rejected)

366.3.2.5 CBT for Chronic LBP

  • Strong evidence
  • Pain management programs

366.3.3 High-Yield Specialist Points

366.3.3.1 Differentiating Sciatica from Other Causes

  • Dermatomal pattern
  • Below knee (true radicular)
  • Above knee (could be facet, SI joint)
  • SLR + crossed SLR (specific for disc herniation)

366.3.3.2 Spurling Test (Cervical Radiculopathy)

  • Neck extension + lateral flexion + axial compression
  • Reproduces arm pain
  • Sensitivity 30-50%, specificity 90%

366.3.3.3 Hoffmann Sign

  • UMN
  • Cervical myelopathy
  • Flick middle finger nail → thumb flexes

366.3.3.4 Lhermitte Sign

  • Neck flexion → electric shock down spine
  • MS, cervical myelopathy, B12 deficiency

366.3.3.5 Acute Spinal Cord Compression Etiology

  • Trauma
  • Metastasis (breast, lung, prostate top)
  • Epidural abscess
  • Hematoma
  • Massive disc

366.3.3.7 Multiple Myeloma

  • Older
  • Back pain + anemia + renal + hypercalcemia
  • SPEP, UPEP, serum free light chains
  • Bone marrow biopsy

366.3.3.8 Spondylolisthesis

  • Slip of one vertebra on another
  • Isthmic (pars defect — young athletes)
  • Degenerative (older)
  • L5-S1 most common
  • Treatment: PT, surgery if refractory + deficit

366.3.3.9 Whiplash

  • Cervical strain after MVA
  • Most resolve weeks
  • Early mobilization
  • Chronic in subset

366.3.3.10 Failed Back Surgery Syndrome

  • Persistent pain after lumbar surgery
  • Multifactorial
  • Spinal cord stimulator
  • Multidisciplinary

366.3.4 Pearls

  • 85% non-specific LBP — stay active + NSAIDs + PT
  • Red flags identify serious causes
  • Imaging only with red flags or refractory > 6 weeks
  • Cauda equina = saddle + urinary + bilateral leg → urgent MRI + decompress within 48 hr
  • Spinal stenosis relieved by flexion
  • Disc herniation SLR positive
  • Spinal epidural abscess triad rare (only 13%)
  • Ankylosing spondylitis = inflammatory + young + HLA-B27
  • Spondylolisthesis common L5-S1
  • Surgery for cauda equina, progressive deficit, refractory > 6 weeks