Double origin of the posteroinferior cerebellar artery: angiographic anatomy and endovascular treatment of concurrent vertebrobasilar dissection.

Objective: The aim of this study was to evaluate the anatomic details and therapeutic implications of the double origin of the posteroinferior cerebellar artery (DOPICA).

Methods: A total of 131 patients with intracranial posterior circulation aneurysms were consecutively treated using endovascular techniques during an 8-year period. We retrospectively searched the angiographies of these patients for evidence of DOPICA and evaluated its anatomic and treatment details and outcomes in cases of concurrent vertebral artery dissection.

Results: DOPICA was found in eight patients. Five patients had a ruptured dissecting lesion at one posteroinferior cerebellar artery (PICA) channel and/or the vertebral artery of cranial PICA origin. In the remaining three patients, DOPICA was incidentally found in cases of P2 or basilar aneurysm. The cranial channel arose from the V4 segment in all eight patients, whereas the caudal channel arose at the atlantooccipital level in seven patients and at the C1 to C2 level in one patient. Internal trapping was chosen to treat the dissecting lesions, because the remaining channel was expected to serve as a route for the PICA-territorial supply. Four of the five patients fully recovered, and one comatose patient eventually died.

Conclusion: The cranial and caudal channels of DOPICA mainly arise at the levels of the intracranial and atlantooccipital spaces, respectively. Treatment for a ruptured dissection involving the PICA or a vertebral artery of PICA origin is challenging because of the fear of PICA territorial infarction. In such a case, the presence of DOPICA allows internal trapping of a dissecting lesion with reduced risk, because the other channel functions as an alternative flow-maintaining route.