A 70-year-old man presented to the emergency department with a painful exacerbation of right trigeminal neuralgia, managed for 5 years with carbamazepine. Clinical examination revealed binocular diplopia due to an abduction deficit in the right eye and hypoesthesia in all divisions of the right trigeminal nerve (V1, V2, V3), without clinical signs of right VII or VIII cranial nerve involvement. High-resolution 3D T2-weighted steady-state MRI (Figure) revealed vertebrobasilar dolichoectasia (VD) with deviation of the right fifth cranial nerve root, complete atrophy of the right sixth cranial nerve, and deviation of the right acoustic-facial nerve bundle.
Open in viewer.
Although VD mainly causes ischemic stroke or brainstem compression, cranial nerve involvement is rare. Abducens nerve compression is exceptional, with 11 cases reported up to 2020,1 and combined fifth and sixth nerve involvement even rarer (2 cases).2.