OBJECTIVE: HydroCoil (MicroVention, Aliso Viejo, CA), a hydrogel-platinum coil hybrid device, is one of various efforts to overcome delayed recanalization of coiled intracranial aneurysms. The purpose of this study was to investigate the outcome of intracranial aneurysms treated with HydroCoils.
METHODS: This multicenter prospective study included 80 aneurysms in 76 patients treated with HydroCoils. There were 32 (40%) ruptured and 48 (60%) unruptured aneurysms; 22 (28%) were large aneurysms (maximal diameter, ≥10 mm) and 58 (72%) were small. Aneurysm volumes were 100 mm3 or more in 48 (60%) and less than 100 mm3 in 32 (40%); in 13 aneurysms (16%), volumes were 600 mm3 or more. Efficacy and safety were evaluated on the basis of degree of initial occlusion, procedure-related complications, and the follow-up result.
RESULTS: Initial aneurysmal occlusion was complete in 60 (75%) aneurysms and near-complete in 14 (17.5%). Procedure-related complications included aseptic meningitis-related problems, including delayed hydrocephalus in 13 patients (28% among cases of unruptured aneurysms) and thromboembolism in two patients. Radiological follow-up data obtained 6 months or more after coil embolization were available in 54 aneurysms (68%) and revealed stable occlusion in 48 (89%) aneurysms, minor recanalization in one (2%), and major recanalization in five (9%). All of the recanalized aneurysms were 600 mm3 or more in volume, and aneurysm volume was a single important variable related to delayed recanalization on multiple logistic regression analysis (P = 0.016).
CONCLUSION: HydroCoil embolization seems to be a feasible treatment option in intracranial aneurysms in terms of initial aneurysmal occlusion rate and durability at the time of the follow-up evaluation; however, caution is required regarding aseptic meningitis and delayed hydrocephalus. Calculated aneurysmal volume of 600 mm3 seems to be critical in determining the anatomic outcome in aneurysms embolized with HydroCoils.