Direct Carotid Cavernous Fistula Due to Rupture of a Cavernous Carotid Aneurysm Embedded Within a Prolactinoma After Cabergoline Administration

Background A small number of reports have described subarachnoid hemorrhage resulting from a ruptured aneurysm embedded within a prolactinoma. To the best of our knowledge, no reports have described an embedded carotid cavernous fistula. We report a patient with carotid cavernous fistula secondary to a ruptured internal carotid artery aneurysm embedded within a prolactinoma. Case Description A 61-year-old woman was referred to our hospital with sudden headache, vomiting, and dizziness. Magnetic resonance imaging demonstrated a small acute subdural hematoma, recurrent prolactinoma, and left cavernous carotid aneurysm. Conservative therapy was initiated. Her serum prolactin level at hospitalization was 11,300 μg/L; therefore, we initiated cabergoline therapy. Twenty days after cabergoline administration, she suddenly presented with left conjunctival injection and pulsatile tinnitus. Angiography showed a left direct carotid cavernous fistula with a connection between the cavernous internal carotid artery and the cavernous sinus via the aneurysm and venous congestion. To prevent hemorrhagic stroke, we scheduled staged surgery. First, we urgently performed embolization of the cavernous sinus and fistula. One month later, to prevent aneurysm rerupture, we performed a radical operation with superficial temporal artery–middle cerebral artery double anastomosis with proximal occlusion of the left internal carotid artery at the cervical portion. The patient was discharged 2 weeks after surgery without neurological deficits. Follow-up angiography revealed complete occlusion of the aneurysm 2 months postoperatively. Conclusions An aneurysm embedded within a prolactinoma should be closely observed when cabergoline administration is started.