A 58-year-old hypertensive man develops sudden-onset right-sided limb ataxia, ipsilateral Horner's syndrome, loss of pain and temperature over the left face and right body, and dysphagia. MRI shows an infarct in the lateral medulla. Which artery is most likely occluded?

• A Anterior inferior cerebellar artery (AICA)
• B Posterior inferior cerebellar artery (PICA) ✓
• C Basilar artery
• D Superior cerebellar artery

Explanation

Wallenberg (lateral medullary) syndrome results from PICA or vertebral artery occlusion. It affects the lateral medulla causing ipsilateral Horner's (descending sympathetics), ipsilateral facial pain/temperature loss (spinal trigeminal nucleus), contralateral body pain/temperature loss (spinothalamic tract), ipsilateral ataxia (inferior cerebellar peduncle), and dysphagia/dysphonia (nucleus ambiguus). AICA infarcts affect the lateral pons, not the lateral medulla.

Reference: BD Chaurasia's Human Anatomy, 8th ed.

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Written and medically reviewed by the StethoPrep medical team.