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• Approach to localizing brainstem syndromes


  1. Localize the area of the brainstem affected (cranial nerve signs)

  2. Localize the tract affected (medial vs lateral syndrome)

  3. Localize the side affected (right vs left syndrome)
• Midbrain


  • Cranial nerves 3 & 4 localizing signs: Diplopia, Dilated pupils, Ptosis
• Pons


  • Cranial nerves 6 & 7 localizing signs: Diplopia, Loss of eye abduction, Facial weakness (not numbness)
• Medulla


  • Cranial nerves 9, 10, & 12 localizing signs: Speech & swallowing problems, Tongue & palate/uvula deviation
• Medial syndrome


  • Corticospinal tract: Motor (hemiplegia & weakness)
  • Medial lemniscus: vibration & position
• Lateral syndrome


  • Spinothalamic: pain & temperature
  • Sympathetic: Horner's
  • Spinocerebellar: ataxia, cerebellar signs
• All cranial nerve lesions are ipsilateral EXCEPT: Palate/uvula deviation: contralateral
• All tract lesions are contralateral EXCEPT: Sympathetic: ipsilateral, Spinocerebellar: ipsilateral
• Clinical scenario


  • Loss of pain and temperature on the right side of the body and left side of the face
  • Dysphagia, hoarseness, and hiccups
  • Palate deviated to the right side
• Diagnosis


  1. Speech & swallowing problems & palate deviation à MEDULLA

  2. Loss of pain & temperature: spinothalamic à LATERAL

  3. Palate deviated to the right: contralateral (exception)

  4. Loss of pain & temperature on the right: contralateral

  5. à LEFT LATERAL MEDULLARY SYNDROME (AKA Wallenberg syndrome)