Pontine infarction caused by medial branch injury of the basilar artery as a rare complication of cisternal drain placement.

We present a rare complication of cisternal drain placement during aneurysm surgery. A ruptured anterior communicating artery aneurysm was clipped through a right pterional approach. A cisternal drain was inserted from the retro-carotid to the prepontine cistern. Postoperatively, a left-sided paresis of the upper extremity had developed. A CT brain scan revealed that the drain was located between the pons and the basilar artery, resulting in a pontine infarction. Vascular neurosurgeons should keep this complication in mind when placing a cisternal drain tube. The drain tube should not be inserted too deep into the prepontine cistern.