Delayed rupture of intracranial aneurysms after placement of intra-luminal flow diverter

Background Though flow diverter is a safe and efficient modality, some patients can experience delayed aneurysmal rupture. The mechanism of delayed rupture is still obscure to us. Methods We performed a systematic search in the PubMed database for patients with delayed rupture of intracranial aneurysms after flow diverter placement. Results A total of 36 articles reporting on 60 patients were included in the final analysis. Of the 49 patients with description of presenting symptoms, six (12.2%) patients were incidentally diagnosed, 39 (87.8%) patients were admitted for aneurysmal rupture or mass effect. Multiple flow diverters were used in 38.3% (18/47) of the patients. Coil assistance was applied in 13.0% (7/54) of the patients. Delayed aneurysmal rupture led to intracranial hemorrhage or carotid–cavernous sinus fistula (CCF) in 76.8% (43/56) and 23.2% (13/56) of the patients, respectively. Of the 55 patients with description of outcome, 14 (25.5%) patients achieved good recovery, one (1.8%) patient was severely disabled, 40 (72.7%) patients died. All of the patients in the CCF group survived and experienced good recovery. Conclusion Increased intra-aneurysmal pressure, destabilization of the aneurysm wall by intra-aneurysmal thrombus, persistent residual intra-aneurysmal flow, characteristics of the specific aneurysm, and mechanical injury by the flow diverter might conjointly contribute to the final delayed rupture. There has been no established preventive measure to decrease the incidence of delayed rupture yet. The treatment and outcome depend on the presentation of delayed rupture. Patients presenting with aneurysm-related intracranial hemorrhage have a dismal outcome. Those presenting with CCFs usually have a satisfactory recovery.