Multiple Rare Anatomic Variations in Anterior and Posterior Cerebral Circulation: A Case Report.

Anatomic variations of intracranial arteries are of paramount importance in neurosurgery and interventional radiology. Three extremely rare arterial variants were found by observing the intracranial vascular anatomy on the magnetic resonance angiography files of a 56-year-old female patient. Firstly, on the left side of the vertebrobasilar axis, a persistent primitive lateral basilovertebral anastomosis was found uniting the left anterior inferior and posterior inferior cerebellar arteries; further, the left anterior inferior cerebellar artery looped above the nerves of the internal auditory canal. Secondly, the right posterior inferior cerebellar artery was shown to be leaving the vertebral artery and had a distal fenestration of the telovelotonsillar segment. Such cases of distal fenestrated posterior inferior cerebellar artery are rare. Thirdly, a partly duplicated anterior communicating artery was also found in the anterior circulation. In conclusion, magnetic resonance angiography helps distinguish and detail discrete and delicate rare arterial variants.