Successful endovascular treatment of a ruptured bihemispheric posterior inferior cerebellar artery aneurysm: illustrative case

Abstract

Background: Normal posterior inferior cerebellar artery (PICA) anatomy is highly variable, but bihemispheric PICA crossing the midline to supply the vascular territory of bilateral cerebellar hemisphere is rare. Herein, the authors reported a rare case of ruptured aneurysm that was associated with bihemispheric PICA and successfully treated endovascularly.

Observations: A 46-year-old woman presented with sudden headache and loss of consciousness because of an intraventricular hemorrhage due to a ruptured aneurysm that was associated with the bihemispheric PICA. Angiography revealed that the aneurysm was located at the bifurcation between the bihemispheric PICA and the bilateral distal PICA. The ruptured aneurysm was successfully occluded using coil embolization, which preserved the parent artery with no procedural-related complication.

Lessons: To the best of the authors' knowledge, this was the first report of a ruptured aneurysm associated with bihemispheric PICA being successfully treated endovascularly. Aneurysm formation may be accelerated by hemodynamic stress and vascular fragility. For neurosurgeons and neurointerventionalists, it is important to understand the anatomical variation of PICA, especially bihemispheric PICA, which is a potential risk factor for a fatal stroke.

Keywords: CT = computed tomography; CTA = CT angiography; DSA = digital subtraction angiography; MRI = magnetic resonance imaging; PICA = posterior inferior cerebellar artery; VA = vertebral artery; bihemispheric PICA; coil embolization; intraventricular hemorrhage; ruptured aneurysm.

FIG. 1.

Initial noncontrasted CT and CTA at admission. Noncontrasted axial (A) and sagittal (B) CT showed a hematoma in the fourth ventricle. CTA axial image (C) and three-dimensional CTA (D) detected a small aneurysm (white arrows) that was located at the main trunk of the right PICA near the fourth intraventricular hemorrhage and was associated with the bleeding.

FIG. 2.

Preoperative DSA. Anteroposterior (A and B) and lateral (C) right vertebral angiography showed a small saccular aneurysm that was located at the main trunk of the right PICA, and it crossed the midline to supply the vascular territory of the bilateral cerebellar hemispheres D: Left vertebral angiography showed the absence of the left PICA. Anteroposterior (E) and lateral (F) three-dimensional DSA showed a small saccular aneurysm that was located at the bifurcation between the main trunk of the right PICA and the bilateral distal PICA.

FIG. 3.

Coil embolization of the aneurysm. Anteroposterior (A) and lateral (C) views of the right vertebral angiography before treatment. Anteroposterior (B) and lateral (D) views of the right vertebral angiography immediately after treatment showed complete occlusion of the aneurysm with preservation of the bihemispheric PICA and the bilateral distal PICA. Anteroposterior (E) and lateral (F) views of three-dimensional DSA immediately after treatment.

FIG. 4.

Follow-up DSA at 7 days after treatment. Anteroposterior (A) and lateral (B) views of right vertebral angiography showed the stability of the coiled aneurysm without regrowth or recurrence. Anteroposterior (C) and lateral (D) views of three-dimensional DSA also showed complete occlusion of the aneurysm without regrowth or recurrence.

FIG. 5.

Follow-up MRI/MR angiography (MRA) after the treatment. A and B: Axial images of fluid-attenuated inversion recovery at 3 weeks after treatment showed no infarction in the bilateral cerebellar hemisphere. C: Axial T2-weighted image at 6 weeks after treatment showed a normal-sized ventricle without hydrocephalus. D: Lateral view MRA at 6 weeks after treatment showed no regrowth or recurrence of the coiled aneurysm. E: Lateral view MRA at 6 months after treatment revealed no regrowth or recurrence of the coiled aneurysm.