A 54-year-old man with chronic hypertension visited ED of a local hospital following the sudden onset of posterior neck pain and left-sided homonymous hemianopsia. A brain CT revealed a subcortical hemorrhage in the right occipital lobe []. He was diagnosed with a hypertensive intracerebral hemorrhage and admitted for several days to receive conservative management before he was discharged home. However, 2 weeks later, he experienced dizziness and visited our ED. A brain MRI (diffusion-weighted images) revealed a high-intensity signal in the left cerebellar hemisphere which corresponded to the area perfused by the left PICA []. The left PICA was poorly depicted on the brain MRA [] and a presumptive diagnosis of atherosclerotic PICA occlusion was made. However, CTA of the extracranial vessels obtained the next day revealed a tapered occlusion of the left VA inside the transverse foramen []. In addition, a thin-slice contrast-enhanced axial image at the C5 level showed a double-lumen sign [], establishing the diagnosis of an extracranial VA dissection. In retrospect, the initial hemorrhage in the right occipital lobe was not an arterial bleeding but was a hemorrhagic infarction secondary to a temporary embolic occlusion of the left posterior cerebral artery. Anticoagulation with warfarin was initiated, and the patient has not experienced a recurrent infarction for over a year.
A 55-year-old woman visited our ED with a complaint of vertigo and sudden-onset headache. A diffusion-weighted MRI revealed a high-signal intensity lesion in the right cerebellar hemisphere [], leading to the diagnosis of CI. Although depiction of the right PICA was poor, a pathologic process involving the PICA remained unclear []. CTA performed the next day revealed a pearl-string lesion at the orifice of the right PICA [], establishing the diagnosis of a right PICA dissection. The patient recovered uneventfully with conservative management, including administration of aspirin. A repeated CTA obtained a month after admission showed improvement in the stenosis of the PICA distal to the dissection [].