Challenges in the management of a ruptured bihemispheric posterior inferior cerebellar artery aneurysm.

BACKGROUND: Bihemispheric posterior inferior cerebellar artery (PICA) is a rare anatomical variant, wherein a single PICA supplies both cerebellar hemispheres. Being the only PICA, treatment of aneurysms arising from this anatomical variant is more complex. We present a case of a ruptured bihemispheric PICA aneurysm and the challenges encountered in its management.

CASE DESCRIPTION: A 54-year-old man presented with giddiness and nausea. Otherwise, he was neurologically intact. CT brain showed a right cerebellar hematoma and intraventricular hemorrhage. Cerebral angiogram revealed a dissecting aneurysm in the retromedullary segment of a right- bihemispheric PICA with a prominent saccular component. Initially, the patient refused to undergo any invasive treatment. However, when a follow-up angiogram showed increase in the aneurysm-sac size, he consented for treatment. Although parent vessel occlusion (PVO) was the clinical recommendation, in view of the patient's apprehensions, only the saccular component of the aneurysm was coil-embolized without parent vessel sacrifice. Fifteen days from the coiling, there was a rebleed from this dissecting aneurysm that was treated with PVO followed by suboccipital craniectomy. He made a reasonable recovery and was MRS1 at 6-month follow-up.

CONCLUSION: In dissecting aneurysms of a bihemispheric PICA, isolated endosaccular occlusion provides uncertain protection from a rebleed while a more reliable treatment with PVO carries unpredictable risk of ischemic complications. The risks of a PVO may be rationalized as a life-saving measure; however, subsequent threshold for posterior fossa decompression should be low.