Sixth cranial nerve palsy secondary to compression by dolichoectatic vertebrobasilar artery.

Dolichoectasia refers to distinct elongation, dilatation and tortuosity of an artery. We present a rare well-illustrated case of dolichoectatic vertebrobasilar artery compressing the cisternal portion of the sixth cranial nerve resulting in chronic sixth nerve palsy. High spatial resolution, three-dimensional, heavily T2-weighted MRI sequences are uniquely positioned to assess the cranial nerves especially in their cisternal and canalicular portions and need to be performed for all patients with non-resolving cranial nerve palsies. Dolichoectatic vessels can be the cause of neurovascular conflict and cause non-resolving oculomotor palsies. © BMJ Publishing Group Limited 2020. No commercial re-use. See rights and permissions. Published by BMJ.