Aneurysms from extracranial, extradurally originating posterior inferior cerebellar arteries: a rare case report.

Background: Aneurysms arising from the PICA are infrequent and those arising from an extracranially originating PICA in the extracranial intradural region are even rare. We report a case of bilaterally extracranial extradurally originating PICAs, each of which had an aneurysm, both being situated below the foramen magnum. This to the best of our knowledge is the first of its kind to be reported.

Case Description: A 35-year-old woman presented with giddiness and headache of 2-day duration. CT scan head revealed blood in the 4(th) ventricle. 4 vessel angiogram revealed bilateral extracranial, extradural origin of PICAs from the vertebral arteries between C1 and C2 vertebrae. Both PICAs were associated with a saccular aneurysm each, both of which were extracranial. She underwent a midline suboccipital craniectomy, C1 arch excision, and clipping of both aneurysms.

Conclusions: We report a very rare case of bilateral extracranial PICA aneurysms from an aberrantly originating PICA (ie, extracranial and extradural).