Intracranial dissection and extracranial hypoplasia of the internal carotid artery.

issection of the intracranial portion of the internal carotid artery (ICA) is an uncommon cause of stroke or transient ischemic attack (TIA). Congenital anomalies of the ICA have been rarely associated with cerebral ischemia. However, unilateral ICA hypoplasia can be frequently associated with intracranial arterial anomalies and altered hemodynamics.1 We describe the case of a woman who had sudden onset of right facial pain and transient left hemiparesis. Diffusion-weighted magnetic resonance imaging (MRI) findings were negative for acute ischemia. Magnetic resonance angiography (MRA) and sonography showed hypoplasia of the right extracranial ICA and vertebral artery (VA) and dissection of the intracranial portion of the right ICA and right middle cerebral artery (MCA), with inverted flow of the right anterior cerebral artery (ACA). At 12-month imaging studies, the intracranial hemodynamics appeared normalized, whereas the extracranial findings were unchanged. This case shows an association between hypoplasia, dissection of the ICA, and cerebral ischemia.