Bioabsorbable polymeric material coils for embolization of intracranial aneurysms: a preliminary experimental study

Object. A new embolic agent, bioabsorbable polymeric material (BPM), was in corporated into Guglielmi detachable coils (GDCs) to improve long-term anat omical results in the endovascular treatment of intracranial aneurysms. The authors investigated whether BPM-mounted GDCs (BPM/GDCs) accelerated the h istopathological transformation of unorganized blood clot into fibrous conn ective tissue in experimental aneurysms created in swine. Methods. Twenty-four experimental aneurysms were created in 12 swine. Tn ea ch animal, one aneurysm was embolized using BPM/GDCs and the other aneurysm was embolized using standard GDCs. Comparative angiographic and histopatho logical data were analyzed at 2 weeks and 3 months postembolization. At 14 days postembolization, angiograms revealed evidence of neck neointima in six of eight aneurysms treated with BPM/GDCs compared with zero of eigh t aneruysms treated with standard GDCs (p < 0.05). At 3 months postemboliza tion, angiograms demonstrated that four of four aneurysms treated with BPM/ GDC were smaller and had neck neointima compared with zero of four aneurysm s treated with standard GDCs (p = 0.05). At 14 days, histological analysis of aneurysm healing favored BPM/GDC treatment (all p < 0.05). the grade of cellular reaction around the coils was 3 +/- 0.9 (mean +/- standard deviati on) for aneurysms treated using BPM/GDCs compared with 1.6 +/- 0.7 for aneu rysms treated using GDCs alone; the percentage of unorganized thrombus was 16 +/- 12% compared with 37 +/- 15%, and the neck neointima thickness was 0 .65 +/- 0.26 mm compared with 0.24 +/- 0.21 mm, respectively At 3 months po stembolization, only neck neointima thickness was significantly different ( p < 0.05). 0.73 +/- 0.37 mm in aneurysms filled with BPM/GDCs compared with 0.26 +/- 0.14 mm in aneurysms filled with standard GDCs. Conclusions. In experimental aneurysms in swine, BPM/GDCs accelerated aneur ysm fibrosis and intensified neck neointima formation without causing paren t artery stenosis or thrombosis. The use of BPM/GDCs may improve longterm a natomical outcomes by decreasing aneurysm recanalization due to stronger in situ anchoring of coils by organized fibrous tissue. The retraction of thi s scar tissue may also decrease the size of aneurysms and clinical manifest ations of mass effect observed in large or giant aneurysms.