Gamma knife surgery-induced aneurysm rupture associated with tissue plasminogen activator injection: A case report and literature review

BACKGROUND: Cases involving delayed development of intracranial aneurysms related to gamma knife surgery (GKS) have been recently reported. Here, we present a rare case of GKS-induced aneurysm rupture after intravenous injection of tissue plasminogen activator (t-PA) for occlusion of the middle cerebral artery (MCA). To the best of our knowledge, this is the first case in which t-PA-induced rupture of a GKS-related unruptured aneurysm. CASE DESCRIPTION: A 56-year-old woman underwent GKS for left trigeminal neuralgia. Eighteen years later, she suddenly experienced MCA occlusion with consciousness disturbance and right hemiparesis. She received an intravenous injection of t-PA and then was transferred to our hospital. We confirmed residual thrombus, and she underwent mechanical thrombectomy successfully. A postthrombectomy brain computed tomography scan revealed subarachnoid hemorrhage with a hematoma in the left cerebellar hemisphere. Cerebral angiography revealed a small irregular-shaped aneurysm at the branching site of the left circumflex branch at the distal position of the anterior inferior cerebellar artery, which was not detected on initial imaging. Coil embolization was performed. One month after the ischemic attack, she was transferred to a rehabilitation hospital, with a modified Rankin Scale score of 5. CONCLUSIONS: The tendency to rupture is greater for GKS-induced aneurysms than for intrinsic unruptured aneurysms, according to previous reports. When performing acute treatment for cerebral infarction in patients with a history of GKS, the presence of aneurysms should be evaluated and we should keep in mind that GKS aneurysms are very small and tend to rupture.