Gross and microscopic histopathological findings in aneurysms of the humanbrain treated with Guglielmi detachable coils

Object. The histopathological characteristics of aneurysms obtained at auto psy or surgery 3 days to 54 months after being treated with Guglielmi detac hable coils (GDCs) were assessed. Methods. Seventeen aneurysms were obtained at autopsy and one was removed a t surgery. Fourteen were examined histologically with the coils in situ. Na ked coils embedded in an unorganized thrombus were found in those aneurysms that had been treated with coils within 1 week earlier. An incomplete repl acement of the intraluminal blood clot by fibrous tissue and a partial memb ranous covering at the aneurysm orifice were observed in those aneurysms th at had been treated with coils between 2 and 3 weeks prior to examination. One small aneurysm treated 6 weeks before harvesting showed formation of an endothelium-lined layer of connective tissue at the orifice. Collagen-rich vascularized tissue surrounding the coils was found in an aneurysm removed at surgery 54 months after coil implantation. Interestingly, six (50%) of 12 aneurysms (two small, three large, and one giant) that had been deemed 1 00% occluded on initial angiography showed tiny open spaces between the coi ls at the neck on gross examination. Conclusions. Endothelialization of the aneurysm orifice following placement of GDCs can occur; however, it appears to be the exception rather than the rule. Tn large aneurysms the process of intraaneurysm clot organization se ems to be delayed and incomplete; tiny open spaces between the coils and an incomplete membranous covering in the region of the neck are frequently en countered. Further longitudinal studies are required to establish the spect rum of healing profiles that may direct our efforts in modifying the GDC sy stem to produce a more stable long-term result.