363.2 🩺 國考版

363.2.1 高頻考點

363.2.1.1 CT vs MRI

  • CT: acute hemorrhage, trauma, bone, calcification, fast
  • MRI: most other pathology

363.2.1.2 MRI Sequences Quick Reference

Sequence Best For
T1 Anatomy
T2 Pathology (bright)
FLAIR MS, edema, periventricular
DWI Acute stroke, abscess
**T2*/SWI** Microbleeds, hemosiderin
Gadolinium BBB breakdown (tumor, infection, MS active)
MRA/MRV Vessels
MRS Metabolites
DTI White matter tracts

363.2.1.3 Acute Stroke Imaging

  • CT: rule out hemorrhage, ASPECTS
  • CTA: LVO (large vessel occlusion)
  • CT perfusion: penumbra
  • MRI DWI: definitive

363.2.1.4 EEG Patterns

  • 3 Hz spike-wave: absence
  • Generalized spike-wave: generalized epilepsies
  • Focal sharp/spike: focal epilepsy
  • Burst suppression: deep coma, anesthesia
  • Triphasic waves: metabolic
  • Periodic lateralized epileptiform discharges (PLEDs): focal lesion, HSV

363.2.1.5 EMG/NCS Patterns

  • Axonal: ↓ amplitude
  • Demyelinating: ↓ conduction velocity, conduction block
  • Decremental RNS: MG
  • Incremental RNS post-exercise: LEMS
  • Myopathic: small short motor units

363.2.1.6 CSF Pattern Memory Aid

Condition Cells Protein Glucose
Bacterial ↑↑ PMN ↑↑ ↓
Viral ↑ lymph ↑ Normal
TB ↑ lymph ↑↑ ↓
Fungal ↑ lymph ↑ ↓
MS Mild ↑ OCB Normal
GBS Normal ↑↑ Normal
SAH RBCs, xanthochromia ↑ Normal
LM disease Lymph ↑ ↓

363.2.1.7 Brain Death EEG

  • Electrocerebral silence (no activity > 2 ÎŒV)
  • 30 min recording
  • Confirmatory test

363.2.2 Important Distinctions

363.2.2.1 Hyperdense on CT

  • Acute blood
  • Calcification
  • Contrast
  • Cysticercosis

363.2.2.2 Ring Enhancement Differential

  • MAGIC DR mnemonic:
    • Metastasis
    • Abscess
    • Glioblastoma
    • Infection (toxoplasmosis)
    • Contusion (resolving)
    • Demyelinating (tumefactive MS)
    • Radiation necrosis

363.2.2.3 DWI Bright Differential

  • Acute stroke
  • Abscess (center)
  • Epidermoid
  • Hypercellular tumor (lymphoma)
  • Status epilepticus
  • Hyperviscosity