Preoperative Digital Subtraction Vertebral Angiograms of a Basilar Apex Aneurysm and Surgical Views. a, Anteroposterior view of preoperative digital subtraction vertebral angiograms of a basilar apex aneurysm arising well below the level of the posterior clinoid process. b, Postoperative view depicting complete obliteration of the lesion. The aneurysm was approached through a right-sided pretemporal transcavernous craniotomy. c, The orbital roof and the anterior clinoid process have been removed, and the optic canal has been unroofed. The temporal lobe has been retracted to expose the posterior clinoid process covered by dura and the entrance of the oculomotor nerve into the posterior part of the roof of the cavernous sinus. d, The optic sheath has been opened, and the dura over the oculomotor nerve has been cut toward he apex of the orbit to expose the nerve on the lateral wall of the cavernous sinus, upper clivus, and posterior clinoid process. e, The posterior clinoid process has been removed along with the superior aspect of the clivus, the dura of the clivus was left in place, and the pituitary gland can be seen inferior and medial to the internal carotid artery. f, The dura of the clivus and over the posterior clinoid process has been removed to expose the basilar artery apex and the aneurysm. g, Final view after the aneurysm has been clipped. (Images courtesy of E de Oliveira)