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Table of Contents    
ORIGINAL ARTICLE
Year : 2013  |  Volume : 61  |  Issue : 3  |  Page : 270-276

Unruptured intracranial aneurysms: Comparison of perioperative complications, discharge disposition, outcome, and effect of calcification, between clipping and coiling: A single institution experience


Department of Neurosurgery, Louisiana State University Health Science Center, Shreveport, Louisiana, USA

Date of Submission28-Feb-2013
Date of Decision09-Apr-2013
Date of Acceptance13-Jun-2013
Date of Web Publication16-Jul-2013

Correspondence Address:
Anil Nanda
Department of Neurosurgery, Louisiana State University Health Sciences, 1501, Kings Highway, Shreveport, Louisiana 71130-3932
USA
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0028-3886.115067

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 » Abstract 

Objective: The aim of the study was to compare the perioperative complications, obliteration rates, discharge dispositions, clinic-radiological outcomes, and the role of calcification between the microsurgical and endovascular treatment of unruptured intracranial aneurysms. Materials and Methods: Retrospective data of the patients treated with microsurgical clipping and those treated by endovascular coiling from January 2007 to August 2012 was collected from the database. Results: Intraoperative rupture was not different in both the treatment groups (4.05% vs. 1.5% clip vs. coil). A total of 9.4% of the patients in the clipping group and 4.5% of the patients in the coiling group suffered postoperative stroke. At last follow up, 89% of the patients in the clipping group and 93% of the patients in the coiling group had favorable outcomes. The mean length of stay was more in clipping group (6.1 vs. 2.7, clip vs. coil, P < 0.05). Patients discharged to home without assistance/rehabilitation services were more in coiling ( P = 0.001). A total of 28.4% (23/81) of the coiled aneurysms were found to have residue neck on postoperative angiograms as compared with 12.6% (10/79) of the clipped aneurysms ( P = 0.01). Calcification within the aneurysm was strongly correlated to the size, perioperative complications, and the outcome ( P < 0.05). However, on excluding the calcified cases the size and outcome do not show a significant correlation. Conclusion: With appropriate patient selection, the majority of the UIAs can be managed by either of the treatment modalities with very low mortality and morbidity. Both the treatment modalities should be employed synergistically.


Keywords: Aneurysms, calcification, clipping, coiling, complications, outcomes, unruptured


How to cite this article:
Sharma M, Brown B, Madhugiri V, Cuellar-Saenz H, Sonig A, Ambekar S, Nanda A. Unruptured intracranial aneurysms: Comparison of perioperative complications, discharge disposition, outcome, and effect of calcification, between clipping and coiling: A single institution experience. Neurol India 2013;61:270-6

How to cite this URL:
Sharma M, Brown B, Madhugiri V, Cuellar-Saenz H, Sonig A, Ambekar S, Nanda A. Unruptured intracranial aneurysms: Comparison of perioperative complications, discharge disposition, outcome, and effect of calcification, between clipping and coiling: A single institution experience. Neurol India [serial online] 2013 [cited 2020 Feb 27];61:270-6. Available from: http://www.neurologyindia.com/text.asp?2013/61/3/270/115067



 » Introduction Top


Unruptured intracranial aneurysms (UIAs) are relatively common lesions with an estimated frequency of 0.4-6% in the general population [1],[2] and are being diagnosed with greater frequency as advances in noninvasive imaging techniques continue to progress. There are many gray areas in the management of UIAs as the morbidity and mortality of therapy has to be balanced with their risk of rupture. The 5-year cumulative rupture rates vary from 0% to 50% depending on the size and the location of the aneurysms. [3] A nationwide study in Sweden had shown that the 5, 10, and 15-year risks of death after subarchnoid hemorrohage (SAH) were 12.9%, 23.6%, and 35.4%, respectively. [4] Therefore the treatment of UIAs is justified only if the morbidity of the treatment is less than the expected risk associated with the rupture. The treatment modalities available for UIAs are observation, microsurgical clipping, and endovascular coiling. However, the best treatment is still a matter of debate. [3] The International Subarachnoid Hemorrhage Treatment Trial (ISAT) trial for ruptured aneurysms demonstrated that, endovascular coiling is superior to clipping in terms of functional outcome, mortality, and epilepsy rates at 1 year. [5] However, similar randomized controlled trials for UIAs to compare treatment options are not available. Numerous studies have demonstrated the efficacy of clipping over coiling and otherwise, however, they are biased by physician preference and selection of a nonrepresentative subgroup of patients. [6],[7],[8],[9],[10],[11] Thus the management of UIAs still remains controversial. The aim of this study was to retrospectively analyze the perioperative complications, discharge dispositions, and clinico-radiological outcomes, in a combined surgical and endovascular cerebrovascular center.


 » Materials and Methods Top


This study was performed using a protocol approved by the Institutional review board. The demographic characteristics of the patient and specific data pertaining to the aneurysms were obtained from the inpatient case records. Calcification was determined by the preoperative computer tomography (CT) scan of the patient. Out of 292 patients with 308 aneurysms, 74 patients with 79 UIAs were managed with microsurgical clipping by the senior author (AN) and from a total of 218 patients with 255 aneurysms in the database, 66 patients with 81 UIAs were managed with endovascular coiling by the interventional neuroradiologist (HC) from January 2007 to August 2012. Endovascular therapy is being carried out at our institute since 2006. Aneurysms were grouped into four groups depending on the size (1) less than 7 mm, (2) 7-12 mm, (3) 13-24 mm, and (4) equal to or greater than 25 mm. Patients with a concomitant ruptured aneurysm, tumors, SAH of unknown origin with UIAs, traumatic and mycotic aneurysms were excluded from the study.

The feasibility of coiling or clipping was assessed by the senior author (AN) and the endovascular team. Treatment decision was based on the location and morphology of the aneurysms, neurological condition of the patient, medical comorbidities, risks involved and finally, on the basis of the patient and family preferences. Intraoperative aneurysm occlusion was assessed by the visual examination in all cases, intraoperative angiography in a few cases and with infrared indocyanine green video angiography (ICGA) during the latter part of the series. Postoperative angiography was obtained whenever the patient developed vasospasm or a new neurological deficit. In patients in the endovascular group, aneurysm obliteration was assessed at the end of the procedure. Obliteration was considered complete (no residual filling) and residual neck (minor aneurysm neck) during control angiography.

Modified Rankin scale (mRS) [12] was used to measure the outcome at the time of admission and at first follow up. Patients with mRS scores 0, 1, and 2 were grouped as having favorable outcome, those with mRS scores 4 and 5 were considered as having bad outcomes and an mRS score of 6 was considered as mortality. Postoperative infarct was defined as any hypo density on CT scan corresponding to the specific vascular distribution. At discharge, patients were grouped into four categories depending on the disposition of the patient to home, home with assistance, rehabilitation, or skilled nursing care. Patients in whom all clinical, radiological, operative, and follow up data was not available were excluded from the study.

Statistical analysis

Statistical analysis was carried out using SPSS v20 (IBM, Inc) and Microsoft Excel. The outcome difference between two groups was analyzed using Pearson's Chi-square test. Comparisons between the clipping and coiling groups were also made using Fisher exact test to generate an odds ratio and P value for the odds ratio. Comparisons were considered significant only if the P < 0.05. Univariate analysis was used to identify the covariates, which might affect the outcome. Binary logistic regression analysis and Pearson's bivariate analysis were done to identify the independent predictors of poor outcome.


 » Results Top


From 2007 to 2012, 79 aneurysms were clipped in 74 patients. There were three patients with two and one patient with three aneurysms who were clipped in a single sitting. A total of 81 aneurysms were coiled in 66 patients, 7 patients with 2, and 4 patients with 3 aneurysms were coiled simultaneously.

Patient and aneurysm characteristics

The mean age in the clipping group was 55 years (range 27-79 years) and 54 years in the coiling group (range 28-74 years). About three-fourth of the patients were females. The most common presenting complaint was headache, followed by incidental diagnosis on imaging done for unrelated symptoms. The overall mean size of the aneurysm was 8.20 ± 7.5 mm in both the groups. A total of 87.5% of the UIAs were located in the anterior circulation and 12.5% were in the posterior circulation [Table 1]. Majority of the anterior circulation aneurysms were clipped and coiling was the most frequently employed procedure for the posterior circulation aneurysms (P < 0.05). Out of 10 giant aneurysms, 3 giant aneurysms were located on the ophthalmic segment, 2 on cavernous internal carotid artery (ICA) and one each on basilar artery, superior cerebellar artery (SCA), ICA bifurcation, middle cerebral artery (MCA) bifurcation, and anterior communicating artery (ACOM). Both the giant posterior circulation aneurysms and cavernous ICA aneurysms were coiled, the rest of the giant aneurysms were clipped.
Table 1: Demographic data, clinical presentation, and aneurysm characteristics of the patients with UIAs

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Complications and outcome

The rate of intraoperative rupture (IOR) was not different between the two treatment groups (P > 0.05). Intraoperative vasospasm was noted in five patients (7.5%) in the coiling group, whereas none in the clipping group. These cases were managed with intraarterial nimodipine infusion during the procedure. Four patients (6.0%) in the coiling group had thromboembolic complications who were managed by intraprocedural thrombolysis. All of the patients who suffered stroke in the clipping group (7 patients, 9.4%) had large and giant aneurysms and temporary clipping was used either during dissection or just before permanent clipping. Four patients (5.4%) in the clipping group developed hydrocephalus in the postoperative period and required ventriculoperitoneal shunting for cerebrospinal fluid (CSF) diversion. Postoperative angiography was performed in 55 patients (74%) in the clipping group and in all patients who underwent endovascular treatment. The total obliteration of the aneurysm was obtained in 72% of the coiled aneurysms and 87% of the clipped aneurysms. These patients with residual neck were followed up and there was no increase in the residual neck size on subsequent angiograms [Table 2].
Table 2: Complications, outcomes and discharge disposition associated with the treatment of UIAs

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Follow up mRS were available for 97.3% patients in the clipping group and 90% of patients in the coiling group. The mean follow up was 11 months in the clipping group and 7 months in the coiling group. At last follow up, 89% of the patients in the clipping group and 93% of the patients in the coiling group had favorable outcome (P = 0.39). All unfavorable outcomes in both the groups were due to the postoperative neurological complications. In the posterior circulation, unfavorable outcome was seen only in one patient with a posterior inferior cerebellar artery (PICA) aneurysm in the clipping group, who had moderate disability and swallowing difficulty, who had shown gradual improvement in the last follow up. One patient (1.7%) in the coiling group and two patients (2.78%) in the clipping group died. The one in the coiling group was due to cardiac arrhythmias and the other two mortalities in the clipping group were in giant anterior circulation aneurysms with intraoperative bleeding, and postoperative infarct superimposed on cardiac comorbidities. All the patients in the coiling group and 86% of the patients in the clipping group were discharged to home without assistance (P < 0.05). Mean length of stay in the hospital was higher in the surgical group as compared with the endovascular group (6.1 days vs. 2.7 days, clip vs. coil, P < 0.05) [Table 2].

Calcification within the aneurismal wall significantly correlated with the size of the aneurysm, intraoperative complications, postoperative complications, and the outcome (P < 0.05). However, on regression analysis, out of various examined variables (age, sex, size, type of circulation, coiling vs. clipping, intraoperative, postoperative complications, calcification) only size of the aneurysm, intraoperative and postoperative complications were correlated to the outcome. The large size of the aneurysm correlated with a poor outcome, however, on excluding the calcified cases this correlation did not reach statistical significance (P > 0.05). A total of 70% of giant aneurysms in our series were calcified and unfavorable outcome was seen in 40% of these aneurysms, both these parameters showed significant difference when compared with the nongiant aneurysms (P < 0.05). Therefore both the size of the aneurysm and calcification within the aneurysm wall were strong predictors of the unfavorable outcome [Figure 1].
Figure 1: Correlation of calcification and the size of the aneurysm (P < 0.05)

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 » Discussion Top


There has been much controversy regarding the optimal management of UIAs and is a matter of contentious debate. According to the International Study on Unruptured Intracranial Aneurysms (ISUIA), [3] the 5 year cumulative rupture rates for patients with no prior history of SAH and aneurysms located in ICA, anterior communicating, anterior cerebral, and MCA were 0%, 2.6%, 14.5%, and 40% for aneurysms less than 7, 7-12, 13-24, and 25 mm or greater, respectively. Similarly the rupture rates of 2.5%, 14.5%, 18.4%, and 50% were documented for aneurysms of the same size categories, respectively, involving the posterior circulations and posterior communicating artery aneurysms. For aneurysms less than 7 mm with no history of SAH, rupture rates were only 0.1% per year. Following the results of ISAT [13] in 2002, there has been a paradigm shift toward endovascular treatment for both ruptured as well as unruptured aneurysms and the majority of UIAs in the USA are now treated with endovascular coiling. [14] This shift can be attributed to the technological advances in the endovascular techniques, with the increasing availability of expertise and resources. With the use of newer techniques such as pipeline embolisation devices or silk flow diverter stents, complete occlusion rates can be impressive even in giant, complex, and fusiform aneurysms. [15],[16] Considering the controversies in the management of UIAs, appropriate patient selection for either of the treatment options is of paramount importance [Figure 2].
Figure 2: The factors which can be used to guide the management of patients with UIAs

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In our series, the IOR rate was higher in the clipped cohort as compared with the coiled group (4.05% vs. 1.5%); however, this difference did not reach statistical significance. In two patients, IOR was associated with poor outcome. Leipzig et al., [17] Brisman et al., [18] and Standhardt et al., [19] also reported higher rates of IOR for the clipped group as compared with the coiled group. Similar results were published by ISUIA with the IOR rate of 6% in the surgical cohort compared with perioperative hemorrhage rate of 2% in the endovascular group. The rate of symptomatic postoperative stroke in our study was 9.4% in the clipping group and 4.5% in the coiling group. In the ISUIA, the cerebral infarction rates in the surgical and endovascular groups were 11% and 5%, respectively. Alshekhlee et al. reported higher rate of perioperative stroke and intracerbral hemorrhage in the clipped group. [2] Niskanen et al. [20] reported no difference (9% vs. 11%, clip vs. coil) in the intraprocedural complication rate among the two treatment groups but the postprocedural complication rate was higher in the surgically treated group. Presence of thrombus, a number of clips and the time of temporary clip application increase the risk of ischemic complications. [21],[22]

In our series, the overall treatment related perioperative morbidity and mortality rates were 8.33% and 2.8% in the clipped and 5% and 1.7% in the coiled group, respectively. Hwang et al. [23] reported higher disability rates with clipping when compared with coiling. They concluded that clipping results is significantly greater disability in the short-term (<6 months) but not in the long-term (>6 months). In our series, the discharge disposition was favorable in the coiling group when compared with that in the clipping group. Barker et al. [24] had shown that when discharge to short-term rehabilitation was considered as an adverse event, coiled patients had better outcome than clipped patients, however, there was no difference when in hospital mortality or long-term discharge was taken into consideration. Alshekhlee et al. [2] and Cowan et al. [25] reported higher mortality rates among the clipped population as compared with the coiled group. The ISUIA reported the 30 day disability and mortality rates of 1.8% and 3% versus 2% and 2.2% in the surgical versus endovascular group, respectively. In our series, the mean length of stay in the hospital was shorter in the coiled group as compared with the clipped group. (2.7 days vs. 6.1 days). According to Hoh et al., [26] coiling was associated with shorter hospital stay in patients with UIAs, similar results were shown by Barker et al. [24] These results indicate that although periprocedural morbidity and mortality rates with endovascular coiling is low in the short-term, the overall morbidity and mortality does not show significant difference in the long-term.

In our series, complete occlusion was achieved in 87% and near complete (small residual neck) in 13% of the aneurysms in the microsurgical group on immediate angiography. Six aneurysms with residual necks were giant and had calcified neck. Other residual aneurysms had a parent or branching vessel involving the base. The obliteration rate of 90-95% following microsurgical clipping of UIA is mentioned in the literature. [21],[27],[28],[29] We use various clipping techniques including tandem clipping, dome clipping (calcified neck), combined straight and fenestrated clipping and orthogonal clipping (perpendicular to the long axis) in cases of giant and calcified aneurysms. Complete obliteration was achieved in 72%, near complete in 28% of the aneurysms in the coiling group, which was lower than reported in the literature. [11],[21],[30],[31] Yue et al. [30] had reported the complete (100%) occlusion rates of 76.25%, nearly complete (90-98%) in 10% and incomplete (60-85%) in 13.75% of the aneurysms. Pandey et al. [32] reported an overall complete (>95%) occlusion rate of 87.8% with the endovascular treatment of posterior circulation aneurysms. In our study, calcification within the aneurysm was strongly correlated to the size of the aneurysm, complications, and the final outcome. Bhatia et al. observed that the calcified aneurysms were 7.8 times more likely to have worse outcomes. [21] The treatment of unruptured calcified aneurysms with either coiling or clipping is technically difficult, which also increases the risk of intraoperative complications. Therefore the optimal management of calcified unruptured aneurysm requires careful planning, taking into consideration both the treatment modalities and the risk factors involved.

In our study, we had analyzed both the treatment modalities for UIAs in terms of perioperative complications, outcomes, discharge dispositions, mortality at our institute. However, it must be mentioned that without randomization direct comparison was not possible between the two treatment groups. There was a selection bias in selecting the cases for either of the treatment modalities. Our results suggest that the optimal treatment strategy for UIAs needs to be individualized with the use of multidisciplinary approaches, with each patient being evaluated by both neurosurgeon and the endovascular team.

In conclusion, with appropriate patient selection, UIAs can be managed by microsurgical clipping or endovascular coiling with favorable outcome and low mortality at short-term follow up. Although higher chances of residual in the coiling group increase the risk for recanalization in long-term follow up. The most optimal treatment modality needs to be individualized with the discussion among neurosurgeons and interventional neuroradiologist regarding the appropriate treatment with low risk and high obliteration rates. Both the treatment modalities should be employed synergistically for the treatment of UIAs. Calcification within the aneurysm was an adverse factor for postoperative complications and final outcome.

 
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    Figures

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    Tables

  [Table 1], [Table 2]

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