In a 45-year-old male patient, a congenital anomaly of the intracranial part of the left vertebral artery accompanying an aneurysm of the vertebro-basilar system was encountered. The patient consulted to a neurosurgeon about headache and vertigo, and a cranial CT revealed an aneurysm at the prepontine cistern. In the cerebral angiography, hypoplastic left vertebral artery accompanying an aneurysm of the basilar tip was detected. The left vertebral artery gave off the posterior inferior cerebellar artery, then became hypoplastic and joined with its counterpart to form the basilar artery. This pattern is called as type II. The aneurysm of the basilar tip was cured via endovascular route. The congenital anomaly discussed on its association with vertigo and aneurysm of basilar tip.
