Neurology
Spinal Cord & Radiculopathy
Neurology

Spinal Cord & Radiculopathy

Cauda equina, spinal epidural abscess, B12, tabes, radiculopathies.

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Subacute combined degeneration (B12)

  • Vegan or pernicious anemia + gait instability + numb feet + ↓vibration + +Romberg
  • Affects dorsal columns + corticospinal tracts
  • Megaloblastic anemia with hypersegmented neutrophils
  • Elevated methylmalonic acid + homocysteine
  • IM B12 replacement; folate alone WORSENS neurologic symptoms

Tabes dorsalis (tertiary neurosyphilis)

  • Lightning leg pains + Argyll Robertson pupils (accommodate but don't react to light) + ataxic gait
  • Treat with IV penicillin G

Spinal epidural abscess

  • Triad: fever + back pain + neuro deficit
  • Risks: IVDU, diabetes, immunosuppression, recent procedures
  • Most common: Staph aureus
  • Emergent MRI + IV antibiotics + surgical decompression

Cauda equina syndrome

  • Saddle anesthesia + urinary retention + ↓rectal tone + LMN leg weakness
  • Most common cause: large disc herniation
  • Emergent decompression within 24–48 hr

Radiculopathies

  • L4: medial leg + ↓knee extension + ↓patellar reflex
  • L5: dorsiflexion (foot drop) + big toe sensation + no reflex change
  • S1: lateral foot + ↓plantarflexion + ↓Achilles reflex
  • Initial conservative (NSAIDs, PT); MRI if severe/progressive

Mechanical back pain

  • Acute after lifting + paraspinal tenderness + no red flags
  • Conservative care, no imaging

Spinal stenosis

  • Neurogenic claudication — pain with walking, relieved by flexion (shopping cart sign)
  • Vascular claudication = relieved by standing
  • MRI lumbar; conservative first, decompression if refractory

High-yield pearls

  • Saddle anesthesia + retention = SURGICAL EMERGENCY
  • Fever + back pain + IVDU/DM = MRI for epidural abscess
  • Anti-NMDA receptor encephalitis: psych + autonomic + seizures in young woman; often ovarian teratoma
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