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Technical nuances and risk factors of complex cerebral aneurysm microsurgery
1108 10:10-10:20
Cerebrovascular/304B
Objective: to evaluate the technical peculiarities of microsurgical treatment of complex cerebral aneurysms (CA) comparing with the ordinary (“simple”) ones and to reveal the risk factors for unfavorable outcomes in patients with complex CA. Material and methods. We conducted the retrospective analysis of microsurgical treatment of 370 patients with 405 CA, treated from 01 Jan 2011 till 31 Dec 2017. They were selected from 1016 patients operated during this period according to the ability of intraoperative video recording. These patients were divided into 2 groups - complex aneurysm (231 patients with 240 CA) and ordinary (simple) aneurysm (139 patients with 165). We supposed CA as complex if it had one or more of anatomical criteria of complexity. These criteria were the following among 405 CA: large (n=29, 7,2%) or giant (n=48, 11,8%) size, non-saccular aneurysm (n=45, 11,1%), broad aneurysmal neck (n=158, 39,0%), atherosclerotic changes/calcinosis in neck area (n=113, 27,9%), atherosclerotic changes/calcinosis in aneurysmal body (n=109, 26,9%), thrombosis of aneurysmal sac (n=74, 18,3%), complex configuration of aneurysm (n=69, 17,0%), complex aneurysmal neck (n=49, 12,1%), arteries arising from aneurysm (n=23, 5,7%), "surgical anamnesis" (clipping/coiling) (n=7, 1,7%). We used nonparametric statistic methods (Fisher exact test, Pearson's chi-squared test, Mann-Whitney test) to reveal the differences between 2 groups (complex and simple CA) according to intraoperative manipulation characteristics concerning all 12 surgeons as well as estimating the data of the most experienced surgeon (204 (55,1%) operated patients and 225 (55,6%) operated CA). The analysis of association/correlation between anatomical criteria of CA complexity and some intraoperative parameters (time of manipulation on CA, number of clipping attempts, temporary clipping and its duration, number of neck remnants, type of clipping, thrombectomy/resection of aneurysm, trapping of aneurysm/parent artery) were conducted using Spearman correlation coefficient and odds ratio (OR) with 95% confidence interval (CI). The differences between groups of patients with complex and simple CA according to clinical outcomes (Glasgow Outcomes Scale (GOS)) were assessed using nonparametric statistic methods (Fisher exact test, Pearson's chi-squared test, Mann-Whitney test). The risk factors for unfavorable outcome were revealed using OR with 95% and Kaplan-Meier analysis. We estimated the clinical outcomes in the whole population (370 patients), in patients with only clipping with or without additional manipulation (thrombectomy/resection of CA, trapping of parent artery/CA) of single complex or simple aneurysm (288 patients, complex CA – 166 (57,6%) patients and simple CA – 122 (42,4%) patients) and in group of revascularization surgery (51 patients, only complex CA). Results. We revealed the statistically significant differences between complex and simple CA according to the following intraoperative parameters among all 12 surgeons: time of manipulation with aneurysms (p<<0,0001; Me[Q1;Q3] - 30[18;45] min on complex CA and 13[7;18] min on simple CA), attempts of clipping (р<<0,0001; Mo[min;max] - 2 [0;7] on complex CA and 1[1;4] on simple CA), usage of temporary clipping (р=0,0002; 50,2% among complex CA and 31,5% on simple CA), time of temporary clipping (p=0,0015; Me[Q1;Q3]) - 7 [3;14] min on complex CA and 4,75 [2,6;6,8] min on simple CA), number of neck remnants (р<<0,0001; 43,4% among complex CA and 3,7% among simple CA). The same results were obtained during analysis of the data of the most experienced surgeon: time of manipulation with aneurysms (p<<0,0001; Me[Q1;Q3] - 22,5[14;38] min on complex CA and 9[6;14] min on simple CA), attempts of clipping (р<<0,0001; Mo[min;max] - 2 [0;6] on complex CA and 1[1;4] on simple CA), usage of temporary clipping (р=0,0001; 49,2% among complex CA and 23,9% on simple CA), time of temporary clipping (p=0,0019; Me[Q1;Q3]) - 6,5[3;13] min on complex CA and 4[2,5;5] min on simple CA), number of neck remnants (р<<0,0001; 41,4% among complex CA and 3,7% among simple CA) We performed the scale of technical difficulty of CA with the assessment of each anatomical criteria of CA complexity in scores. The following value of anatomical criteria of CA complexity were revealed according to the impact on some intraoperative parameters: thrombosis of aneurysm (36 scores), size of aneurysm 15 mm and more (28 scores), broad neck (27 scores), arteries from aneurysm (21 scores), changes in neck area (20 scores), complex neck (18 scores), nonsaccular aneusym (17 scores), changes in aneurysmal body (15 scores), complex configuration of aneurysm (6 scores).«Surgical anamnesis» had no statistical influence of intraoperative parameters because of few cases (n=7) so we considered the value of this criteria as 0 scores. Surprisingly, there were no any statistical correlations between anatomical criteria of CA and GOS: large aneurysm size (OR = 1.405, 95% CI [0.601 - 3.287], р= 0,28); giant aneurysm size (OR = 1.679, 95% CI [0.840 - 3.353], р=0,1); nonsaccular aneurysm (OR = 0.821, 95% CI [0.378 - 1.784], р=0,38); broad neck (OR = 0.732, 95% CI [0.353 - 1.516], р=0,25); changes in neck area (OR = 0.992, 95% CI [0.510 - 1.931], р=0,55); changes of aneurysmal body (OR = 0.865, 95% CI [0.471 - 1.588], р=0,37); thrombosis of aneurysmal sac (OR = 1.170, 95% CI [0.623 - 2.195], р=0,34); complex configuration of aneurysm (OR = 1.522, 95% CI [0.809 - 2.862], р=0,12); complex neck of aneurysm (OR = 0.470, 95% CI [0.195 - 1.133], р=0,06); arteries from aneurysm (OR = 2.086, 95% CI [0.851 - 5.113], р=0,08); “surgical anamnesis” of aneurysm (OR = 2.305, 95% CI [0.500 - 10.617], р=0,24). Also, there were no statistical correlation between "aneurysm value" in scores and GOS in the whole population as well as in the group of patients with aneurysm clipping and in group of revascularization surgery - p=0,5, R=-0,04; p=0,6, R=0,04 and p=0,22, R=-0,17 correspondently. The most important risk factors for unfavorable outcomes in the whole population with complex CA were vertebrobasilar localization of CA and necessity for revascularization surgery. Concerning only complex CA clipping the risk factors were low experience of surgeon, surgery in first 72 hours after complex CA rupture, Hunt-Kosnik III-V grade, intraventricular hemorrhage, time of manipulation with complex CA more than 20 minutes, one attempt of clipping and “simple” clipping, intraoperative CA rupture, sopor or coma after surgery, ischemic area after surgery. Among patients with revascularization surgery the risk factors for unfavorable outcomes were such type of bypass as intra-intracranial anastomosis, intraoperative hypothermia and its severity more than 33,5 С0, total time of recipient arteries temporary clipping more than 55 minutes, duration of main surgery period more than 190 minutes: in postoperative period - bypass thrombosis, ischemic area and its volume more than 80 cm3, hypoperfusion area and decrease of regional cerebral flow less than 37 ml/10gг/min. Conclusion. There are objective differences between complex and simple aneurysms according to the intraoperative parameters even in the most experienced hands. However, the presence of any anatomical criteria or their combination (sum of scores by scale of technical difficulty) do not correlate with the clinical outcome. The most important risk factors for unfavorable outcome are the experience of surgeon, type of aneurysm obliteration, aneurysm localization, time of manipulation with aneurysm and some peculiarities of intra – and postoperative period, especially in revascularization surgery.