A 58-year-old man presents with ipsilateral Horner's syndrome, contralateral loss of pain and temperature, ipsilateral cerebellar ataxia, and dysphagia. MRI reveals an infarct in the lateral medulla. Which artery is most likely occluded?

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

Explanation

Occlusion of the PICA or the vertebral artery causes lateral medullary (Wallenberg) syndrome. Features include ipsilateral Horner's syndrome (descending sympathetic fibers), ipsilateral facial pain/temperature loss (spinal trigeminal nucleus), contralateral body pain/temperature loss (spinothalamic tract), ipsilateral cerebellar ataxia (inferior cerebellar peduncle), and dysphagia/hoarseness (nucleus ambiguus). The AICA supplies the lateral pons, causing a different syndrome with ipsilateral deafness and facial palsy.

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

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Written and medically reviewed by the StethoPrep medical team.