362.3 🏥 內科專科考前版

362.3.1 Localization Pearls

362.3.1.1 Cortical Sensory vs Primary Sensory

  • Cortical: stereognosis, graphesthesia, two-point, double simultaneous extinction
  • Primary: pain, temp, vibration, position

362.3.1.2 Brainstem Crossed Signs

  • Lateral medullary (Wallenberg): ipsilateral face, contralateral body
  • Weber: ipsilateral CN III, contralateral hemiparesis (midbrain)
  • Millard-Gubler: ipsilateral CN VI, VII, contralateral hemiparesis (pons)

362.3.1.3 Spinal Cord Syndromes

  • Anterior cord: bilateral motor + pain/temp, preserved vibration/position
  • Central cord (syringomyelia): cape distribution, dissociated sensory
  • Brown-Séquard (hemisection): ipsilateral UMN + position; contralateral pain/temp
  • Posterior column: vibration/position loss
  • Cauda equina: bilateral leg LMN, saddle anesthesia, bowel/bladder
  • Conus medullaris: bowel/bladder + leg variable

362.3.2 Recent Updates

362.3.2.1 Amyloid + Tau PET

  • Alzheimer biomarkers
  • Lecanemab eligibility
  • Pittsburgh compound B, florbetapir, flutemetamol (amyloid)
  • Flortaucipir (tau)

362.3.2.2 DaTSCAN (123I-FP-CIT SPECT)

  • Dopamine transporter imaging
  • Differentiates PD/parkinsonism from essential tremor

362.3.2.3 Neuroimmunology

  • Anti-NMDA-R, GABA-B-R, LGI1, CASPR2 antibodies
  • Onconeural antibodies (Hu, Yo, Ri, Ma, CV2)
  • Autoimmune encephalitis

362.3.2.4 Genetic Panels

  • ALS panel
  • Hereditary ataxia
  • CMT panel
  • Dystonia/parkinsonism
  • Hereditary dementia

362.3.3 High-Yield Specialist Points

362.3.3.1 Approach to “Numbness”

  • Localize: distribution
  • Dermatomal: root
  • Distal/symmetric: peripheral neuropathy
  • Crossed: brainstem
  • Hemisensory: cortical
  • Level: spinal cord

362.3.3.2 Approach to “Weakness”

  • UMN vs LMN
  • Distribution (proximal, distal, hemi, para, quad)
  • Time course
  • Associated features (fasciculations, atrophy, sensory, cranial)

362.3.3.3 Approach to “Dizziness”

  • Vertigo (spinning) → vestibular
  • Presyncope → cardiac, hypotension
  • Disequilibrium → cerebellar, sensory
  • Lightheaded → anxiety, metabolic

362.3.3.4 Approach to “Coma”

  • Bilateral hemispheric vs brainstem
  • Pupils (size, reactivity)
  • Eye movements (oculocephalic, oculovestibular)
  • Motor response
  • Brainstem reflexes

362.3.3.5 CSF Pearls

  • Lymphocytic with normal glucose: viral, MS, autoimmune
  • Lymphocytic with low glucose: TB, fungal, malignancy (LM disease)
  • PMN with low glucose: bacterial
  • Eosinophilic: parasitic
  • Atypical lymphocytes: lymphoma
  • Cytology + flow if suspect malignancy

362.3.3.6 Imaging Patterns

  • Ring-enhancing lesions:
    • Tumor (glioblastoma, metastasis, lymphoma)
    • Abscess (DWI bright center vs tumor dark)
    • Demyelinating lesion (tumefactive MS)
    • Resolving hemorrhage
  • Restricted diffusion (DWI):
    • Acute ischemia
    • Cytotoxic edema
    • Abscess content
    • High cellularity tumor (lymphoma)
  • Symmetric enhancement:
    • Basal ganglia: heavy metal, hypoxic
    • Limbic: autoimmune encephalitis, HSV

362.3.4 Pearls

  • Localize first (where), then etiology (what)
  • History most important (onset, course, distribution)
  • UMN vs LMN critical
  • MRI > CT for most pathology
  • DWI for acute stroke
  • CSF patterns to memorize
  • GCS for trauma + coma
  • Brainstem crossed signs
  • Spinal cord syndromes (anterior, central, Brown-Séquard, posterior, cauda equina)