Results from a new study suggest that prolonged imaging after endovascular treatment, if there is adequate occlusion of intracranial aneurysms at six months, may often be unnecessary.
The research from The Netherlands which was published in Stroke in May 2011 and also shared at the recent World Federation of Interventional and Therapeutic Neuroradiology (WFITN) meeting in Cape Town, South Africa, sheds light on the frequency and risk factors in 400 patients with 440 aneurysms.
Principal investigator of the study, Sandra P Ferns, Department of Radiology, Academic Medical Center, Amsterdam, The Netherlands, told NeuroNews that prolonged imaging is almost always carried out for all patients, with all kinds of aneurysms. “From previous studies, we know that overall risk of aneurysm re-opening and re-treatment are 20 and 10%, respectively. In our selected group of patients with adequate aneurysm occlusion six months after coiling, these risks were 2.5 and 0.7%, respectively. This proves that virtually all aneurysm re-openings occur in the first six months after coiling, and late re-opening in aneurysms with a good result on first (6 months) follow-up imaging, is very rare.”
Ferns also stated that this finding was not at all widely accepted, and that the research group hoped to be able to convey the message not to do prolonged imaging follow-up in all patients with a coiled aneurysm.
A secondary finding from the study is that large size and location on basilar tips are independent predictors for late re-opening of aneurysms. Investigators showed that aneurysms that are 10mm or more in size, and those located on the tip of the basilar artery have a higher risk of re-opening late, despite adequately occlusion at six months.
The study set out to assess the occurrence of late (over five years) aneurysm re-opening and possible risk factors, as the risk of late re-opening in aneurysms that are adequately occluded six months after coiling is largely unknown.
The researchers included 1,808 intracranial aneurysms which were coiled in 1,675 patients at seven medical centres from January 1995 to June 2005, in the study. They found that at six months, 1,066 aneurysms in 971 patients were adequately occluded. In this group of patients, six years after coiling, 400 patients with 440 aneurysms underwent 3 Tesla magnetic resonance angiography to assess the current occlusion status of the aneurysms.
They calculated aneurysm re-opening and re-treatment and assessed the risk factors for late re-opening by univariate and multivariate logistic regression analysis. This included the sex of the patient, rupture status of aneurysms, aneurysm size ≥10mm, and aneurysm location.
Ferns and colleagues found that late re-opening had occurred in 11 of 400 patients (2.8%; 95% CI, 1.4–4.9%) with 440 aneurysms (2.5%; 95% CI, 1–4%); three of the re-opened aneurysms were re-treated (0.7%; 95% CI, 0.2–1.5%).
Independent predictors for late re-opening were aneurysm size ≥10mm (OR 4.7; 95% CI, 1.3–16.3) and location on basilar tip (OR 3.9; 95% CI, 1.1–14.6). They also found that there were no late re-openings in the 143 anterior cerebral artery aneurysms.
The researchers concluded that for the vast majority of adequately occluded intracranial aneurysms six months after coiling (those <10mm and not located on basilar tip), prolonged imaging follow-up within the first five to 10 years after coiling does not seem beneficial for detecting re-opened aneurysms that need re-treatment. “Whether patients might benefit from screening beyond the five- to 10-year interval is not yet clear,” they wrote.
“The fact that in select cases, the chance of late re-opening is increased 4.7 and 3.9 times in large and basilar tip aneurysms, respectively, is of less importance. It just indicates that in select cases the treating physician should consider prolonged (more than six months) imaging follow-up to detect re-opening,” said Ferns.