What artery is most likely affected in an old hypertensive man presenting with ataxia, ipsilateral facial sensory loss, dysphagia, Horner's syndrome, and contralateral lower limb weakness?

PICA (Posterior Inferior Cerebellar Artery) - Answer A

The clinical presentation of ataxia, ipsilateral facial sensory loss, dysphagia, Horner's syndrome, and contralateral body sensory/motor findings is classic for lateral medullary syndrome (Wallenberg syndrome), which results from PICA territory infarction. 1

Why PICA is the Correct Answer

This constellation of symptoms represents the pathognomonic presentation of lateral medullary syndrome:

• Ipsilateral findings include Horner's syndrome, facial pain/temperature loss, cerebellar ataxia, and dysphagia due to involvement of the lateral medulla 1, 2, 3

• Contralateral findings include loss of pain and temperature sensation in the body (and the mentioned contralateral lower limb weakness fits this pattern) 2, 4, 3

• PICA typically arises from the vertebral artery and supplies the lateral medulla and inferior cerebellum, making it the primary vessel responsible for this syndrome 1

• In elderly hypertensive patients, large-artery atherosclerotic disease in the vertebrobasilar system is the most common cause, particularly affecting the distal vertebral or proximal basilar artery, with vertebral artery stenosis being the typical culprit lesion 1

Why Other Options Are Incorrect

Basilar artery occlusion (Option D) would produce:

• Bilateral findings rather than this unilateral lateral medullary presentation 1
• Altered consciousness and involvement of multiple posterior circulation territories 1
• More extensive brainstem dysfunction including quadriparesis, locked-in syndrome, or coma

AICA (Option B) territory infarction produces:

• Lateral pontine syndrome, not medullary syndrome 5
• Different cranial nerve involvement (typically CN VII and VIII with facial paralysis and hearing loss)
• The clinical picture does not match AICA distribution

Anterior cerebellar artery (Option C):

• This is not a standard anatomical vessel designation
• Does not correspond to the lateral medullary territory

Clinical Pearls

• Wallenberg syndrome can occur even with normal angiographic findings in some cases, as vertebral artery dissection may not always be visible 4, 5
• Symptoms can evolve over days rather than presenting acutely all at once, which is important for diagnosis 6
• Headache is a common accompanying symptom, often related to vertebral artery dissection as the underlying etiology 4