Congenital Bilateral C2 Transverse Foramina Stenosis Causing Adult-Onset Vertebrobasilar Insufficiency and Posterior Circulation Stroke.

Vertebrobasilar insufficiency leading to posterior circulation infarcts caused by congenital hypoplasia of the bilateral transverse foramina at the C2 level, affecting the caliber and flow of the bilateral distal cervical vertebral arteries in an adult, has not been previously reported. A 41-year-old male presented with episodic dizziness for a period of 1 year prior to consultation. Computed tomography angiography of the head and neck demonstrated congenital hypoplasia of the bilateral C2 transverse foramina, with absence of the vertebral arteries in each of the foramina and collateral reconstitution of diminutive intracranial vertebral artery segments. Brain MRI showed postinfarction encephalomalacia in the bilateral cerebellar hemispheres. The patient was considered not a surgical or endovascular candidate and was managed conservatively with antiplatelet therapy. Congenital anomalies of the bilateral cervical transverse foramina may present with vertebrobasilar insufficiency and infarction in adulthood.