Microsurgical Clipping of Unruptured Anterior Circulation Aneurysms—A Global Multicenter Investigation of Perioperative Outcomes

Neurosurgery 94:1218–1226, 2024

Microsurgical aneurysm repair by clipping continues to be highly important despite increasing endovascular treatment options, especially because of inferior occlusion rates. This study aimed to present current global microsurgical treatment practices and to identify risk factors for complications and neurological deterioration after clipping of unruptured anterior circulation aneurysms.

METHODS: Fifteen centers from 4 continents participated in this retrospective cohort study. Consecutive patients who underwent elective microsurgical clipping of untreated unruptured intracranial aneurysm between January 2016 and December 2020 were included. Posterior circulation aneurysms were excluded. Outcome parameters were postsurgical complications and neurological deterioration (defined as decline on the modified Rankin Scale) at discharge and during follow-up. Multivariate regression analyses were performed adjusting for all described patient characteristics.

RESULTS: Among a total of 2192 patients with anterior circulation aneurysm, complete occlusion of the treated aneurysm was achieved in 2089 (95.3%) patients at discharge. The occlusion rate remained stable (94.7%) during follow-up. Regression analysis identified hypertension (P < .02), aneurysm diameter (P < .001), neck diameter (P < .05), calcification (P < .01), and morphology (P = .002) as preexisting risk factors for postsurgical complications and neurological deterioration at discharge. Furthermore, intraoperative aneurysm rupture (odds ratio 2.863 [CI 1.606-5.104]; P < .01) and simultaneous clipping of more than 1 aneurysm (odds ratio 1.738 [CI 1.186-2.545]; P < .01) were shown to be associated with an increased risk of postsurgical complications. Yet, none of the surgical-related parameters had an impact on neurological deterioration. Analyzing volume-outcome relationship revealed comparable complication rates (P = .61) among all 15 participating centers.

CONCLUSION: Our international, multicenter analysis presents current microsurgical treatment practices in patients with anterior circulation aneurysms and identifies preexisting and surgery-related risk factors for postoperative complications and neurological deterioration. These findings may assist in decision-making for the optimal therapeutic regimen of unruptured anterior circulation aneurysms.

Characteristics of Unruptured Compared to Ruptured Intracranial Aneurysms: A Multicenter Case–Control Study

Neurosurgery 83:43–52, 2018

Only a minority of intracranial aneurysms rupture to cause subarachnoid hemorrhage.

OBJECTIVE: To test the hypothesis that unruptured aneurysms have different characteristics and risk factor profiles compared to ruptured aneurysms.

METHODS: We recruited patients with unruptured aneurysms or aneurysmal subarachnoid hemorrhages at 22 UK hospitals between 2011 and 2014. Demographic, clinical, and imaging data were collected using standardized case report forms. We compared risk factors using multivariable logistic regression.

RESULTS: A total of 2334 patients (1729 with aneurysmal subarachnoid hemorrhage, 605 with unruptured aneurysms) were included (mean age 54.22 yr). In multivariable analyses, the following variables were independently associated with rupture status: black ethnicity (odds ratio [OR] 2.42; 95% confidence interval [CI] 1.29-4.56, compared to white) and aneurysm location (anterior cerebral artery/anterior communicating artery [OR 3.21; 95% CI 2.34-4.40], posterior communicating artery [OR 3.92; 95% CI 2.67-5.74], or posterior circulation [OR 3.12; 95% CI 2.08-4.70], compared to middle cerebral artery). The following variables were inversely associated with rupture status: antihypertensive medication (OR 0.65; 95% CI 0.49-0.84), hypercholesterolemia (0.64 OR; 95% CI 0.48-0.85), aspirin use (OR 0.28; 95% CI 0.20-0.40), internal carotid artery location (OR 0.53; 95% CI 0.38-0.75), and aneurysm size (per mm increase; OR 0.76; 95% CI 0.69-0.84).

CONCLUSION: We show substantial differences in patient and aneurysm characteristics between ruptured and unruptured aneurysms. These findings support the hypothesis that different pathological mechanisms are involved in the formation of ruptured aneurysms and incidentally detected unruptured aneurysms. The potential protective effect of aspirin might justify randomized prevention trials in patients with unruptured aneurysms.

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