Dissecting Aneurysm of Vertebral Artery Manifestating as Contralateral Abducens Nerve Palsy
A 38-year-old man was admitted for management and evaluation of a headache that had persisted 6 days. The headache had initially developed after completing a marathon. The patient had visited the visited emergency department in our institution 3 days later. Neurologic and laboratory examinations at that time revealed no abnormalities. Computed tomography (CT) scan revealed no evidence of hemorrhage. The patient was discharged receiving analgesic and further radiologic tests were recommended. On the present admission, the patient was alert and displayed no signs suggesting neurologic deficits. Time of flight magnetic resonance angiography () and axial magnetic resonance angiography source image () disclosed a fusiform dilatation of the right vertebral artery involving the proximal portion of the posterior inferior cerebellar artery (PICA). The patient suddenly suffered from severe headache with diplopia a day before the scheduled cerebral angiography. Neurologic tests revealed nuchal rigidity and impairment of conjugate left lateral gaze. Emergent intracranial CT demonstrated a high density area in the basal cistern and prepontine cistern without ventriculomegaly ().\nRight vertebral angiography () revealed a dissecting aneurysm of right distal vertebral artery compromising proximal PICA with blood supplying to the left proximal portion of PICA through glomus-like vascular channel from right VA. In particular, the vertebrobasilar artery was remarkable flexed to the inferior on the left side. A double-stent method was performed for ruptured dissecting vertebral artery aneurysm. No diffusion restriction was found in follow-up magnetic resonance imaging (MRI) of the brain stem (). Four weeks later, another angiography () illustrated the upward displacement of the vertebrobasilar artery compared with previous images and a CT scan () showed hemorrhage resolution in the prepontine cistern. Full recovery of left abducens nerve paresis was achieved in 11 weeks after onset ().