Intracranial aneurysms are relatively frequently encountered in patients with brain arteriovenous malformations (BAVMs). They may be located on the circle of Willis, on arterial feeders, or even inside the nidus. Because BAVM-associated aneurysms represent a risk factor of bleeding, the question of the timing and modality of their management remains a matter of debate in unruptured BAVMs. The authors present a case of fatal periprocedural rupture of a flow-related aneurysm (FRA) during the removal of the microcatheter after injection of a liquid embolic agent. A 40-year-old man was treated at the authors' institution for the management of a Spetzler-Martin Grade III left unruptured frontal BAVM, revealed by seizures and a focal neurological deficit attributed to flow steal phenomenon. After a multidisciplinary meeting, endovascular treatment was considered to reduce the flow of the BAVM. A proximal FRA located on the feeding internal carotid artery (ICA) was purposely left untreated because it did not meet the criteria of the authors' institution for preventative treatment (i.e., small size [2.5 mm]). During embolization, at the time of microcatheter retrieval, and after glue injection, the aneurysm unexpectedly ruptured. The aneurysm's rupture was attributed to the stress (torsion/flexion) on the ICA caused by the microcatheter removal. Despite the attempts to manage the bleeding, the patient eventually died of the acute increase of intracranial pressure related to the massive subarachnoid hemorrhage. This case highlights a previously unreported mechanism of FRA rupture during BAVM embolization: the stress transmitted to the parent artery during the removal of the microcatheter.