Fourth down and five.

Binocular diplopia and right hemifacial numbness developed in a 52-year-old woman after resection of a right temporal lobe glioblastoma. Based on the Parks-Bielschowsky 3-step test, she was diagnosed with a right cranial nerve (CN) IV palsy in addition to right CN V dysfunction. Iatrogenic diplopia may result from temporal lobe surgery due to the intimate relationship of CN IV and CN III to the mesial temporal lobe. In addition, injury to CN V within Meckel cave is believed to be the cause of facial numbness in some patients after temporal lobe surgery. The anatomy of the intracranial portion of CN IV is reviewed, and the etiologies of CN IV palsy are discussed.