We describe the treatment of ruptured vertebral artery dissecting aneurysms (VADAs) involving the posterior inferior cerebellar artery (PICA) and elucidate an association between the vascular territory of the PICA and the changes in aneurysmal morphology after endovascular proximal occlusion (PO).
We treated five cases of ruptured VADA involving the PICA by endovascular PO just after angiography on the day of onset. We classified the PICAs into two types: PICAs that bifurcated into the medial and lateral trunk (Type A) and PICAs that did not bifurcate and supplied only a small area (Type B). We then compared changes in aneurysmal morphology after PO by contralateral vertebral artery angiography.
Three Type A PICAs and two Type B PICAs were assessed. In the three Type A cases, a whole aneurysm was observed just after PO. These aneurysms had increased in size 1–2 weeks after PO in two cases but remained unchanged in the third case. In all three cases, an occipital artery-PICA bypass and PICA clipping were performed during the subacute stage. In the two Type B cases, the aneurysms were partially observed just after PO, but 1–2 weeks later, the aneurysms were not apparent and no further treatment was required.
After PO during the acute stage of ruptured VADA involving the PICA, the aneurysms with Type A PICAs were more likely to remain; therefore, additional treatment with PICA revascularization and PICA clipping should be planned for such cases. However, for aneurysms with Type B PICAs, no additional treatment was required.