Dissection of the posterior inferior cerebellar artery in a young adult with cerebellar infarct.

The posterior inferior cerebellar artery (PICA) is frequently involved in dissection of the vertebral artery (VA); however, isolated PICA dissection has rarely been reported. A 37-year-old man experienced acute and progressive drowsiness, vertigo, occipital headache, vomiting, and ataxia. There was no precedent trauma or chiropractic manipulation. Neurologically, he had dysmetria of the left extremities. His NIHSS score was 3. Brain magnetic resonance imaging showed an acute cerebellar infarct in the left PICA territory. Magnetic resonance angiography showed a faint signal adjacent to the junction of the left VA and PICA, suggesting a vascular shadow. Catheter angiography showed focal stenosis with a post-stenotic fusiform aneurysmal dilatation of the left proximal PICA that was highly suggestive of dissection with pseudoaneurysm formation. He was treated with clopidogrel and was free of neurological symptoms 3 months after the stroke event. Isolated PICA dissection may be considered in patients with PICA territory infarct or subarachnoid hemorrhage. Treatment depends on the manifestations; ruptured dissecting aneurysms are often treated with surgery or embolization, and infarcts are usually treated with antithrombotic agents.