(Case courtesy: Sapthagiri digital imaging center, Bangalore)

Right PICA territory infarct, with probably long-segment disease involving right vertebral artery.

What is a serious complication of these kind of infarcts?

These infarcts may not be clinically evident, and usually present at a later stage. PICA territory infarcts with long-segment involvement may carry a poor prognosis, due to gradual progression in mass effect, and brainstem involvement with hydrocephalus due to territorial progression or mass effect. Many-a-times, it needs a decompression craniotomy.

In the given case, is there an evidence of lateral medullary syndrome?

Yes, right lateral medulla is involved.

Which cerebral artery is most variable in its course, origin and distribution?

PICA is most variable cerebral artery. Approx. 20% arise from extracranial vertebral artery. Approx. 10% arise from basilar artery. In 2% of cases, they are bilaterally absent.