Ruptured Distal Superior Cerebellar Artery Aneurysm After Gamma Knife Radiosurgery for Trigeminal Neuralgia: A Case Report and Review of the Literature.

Background Intracranial aneurysm formation after Gamma Knife radiosurgery (GKRS) is a rare complication that has only recently been reported in the literature. We report the case of a fatal distal superior cerebellar artery (SCA) aneurysm rupture in a woman treated twice with GKRS for trigeminal neuralgia along with a review of the literature regarding radiation-induced aneurysms. Case Description A 77-year-old white woman with a history of refractory right-sided trigeminal neuralgia treated with GKRS in 2001, and again in 2006 after a relapse, presented to our emergency department with complaints of a sudden-onset severe headache associated with vomiting, right eye vision loss, left-sided facial droop, and left-sided weakness with no history of hypertension or smoking prior to presentation. Initial head computed tomography scan without contrast demonstrated an intraparenchymal hemorrhage centered in the right middle cerebellar peduncle with subarachnoid hemorrhage in the basal cisterns and extension into the fourth ventricle causing early hydrocephalus. Head computed tomography angiography (CTA) demonstrated a distal right SCA aneurysm adjacent to the hemorrhage. The patient's mental status deteriorated into coma after suspected rerupture during the CTA requiring immediate intubation, external ventricular drain placement, and emergent cerebral angiogram with coil embolization. Ultimately, the patient never recovered despite medical and surgical management; therefore, care was withdrawn in accordance with her known wishes. Conclusions The pathophysiologic association of aneurysm formation after GKRS remains to be elucidated, but given the potentially fatal consequences of aneurysm rupture, we advocate for further research and propose serial vascular imaging during the postradiosurgery follow-up period for iatrogenic aneurysm formation surveillance.