Bilateral spontaneous dissection of the posteroinferior cerebellar arteries: case report.

OBJECTIVE AND IMPORTANCE: Cervicocerebral arterial dissections occur when blood extrudes into the wall of an artery supplying the brain. The resulting intramural hematoma may compromise the lumen and cause an aneurysmal dilation. Dissecting aneurysms are now recognized with increasing frequency as a cause of strokes. They usually occur spontaneously or are associated with trivial trauma to the artery. A dissecting aneurysm of the posteroinferior cerebellar artery (PICA) is very rare, however. We present a case with ischemic episode and successive subarachnoid hemorrhage caused by bilateral dissection of the PICAs.

CLINICAL PRESENTATION: A 47-year-old man experienced sudden onset of cerebellar infarction that rapidly resulted in subarachnoid hemorrhage. Angiography revealed a typical pearl-and-string sign in the right PICA and an irregular stenosis in the left PICA. The patient died shortly after admission. Autopsy demonstrated bilateral dissection of the PICAs not involving the vertebral artery.

CONCLUSION: The incidence of intracranial dissecting aneurysms most frequently occurs in the vertebral artery, but the PICA is only rarely involved, especially bilaterally. We are not aware of any other such case in the literature.