Cerebellar top-of-the-basilar syndrome.

We present a patient with unusual cerebrovasculature due to the absence of anastomosis between anterior and posterior circulations and bilateral fetal posterior cerebral arteries. This resulted in an atypical 'cerebellar' top-of-the-basilar syndrome, with bilateral superior cerebellar artery infarctions. We review the clinical presentation and radiologic findings and explain the embryologic origin of this vascular anatomy.