Parent artery sacrifice for ruptured aneurysms in acute and chronic phases: A systematic review
Correspondence Address: Source of Support: None, Conflict of Interest: None DOI: 10.4103/0028-3886.232310
Source of Support: None, Conflict of Interest: None
Keywords: Aneurysm, intracranial, parent vessel, ruptured, sacrifice
Most of the ruptured cerebral aneurysms can be treated with clipping or coil embolization. However, these treatments are not applicable for particular aneurysms such as blister-like aneurysms or dissecting aneurysms because of aneurysmal size (large/giant) or a fragile neck (blister-like aneurysms or dissecting aneurysms).,,,,,, Therefore, studies related to treatment methods other than clipping and stent placement, such as parent vessel sacrifice (PVS) with or without bypass surgery, have been reported sporadically.,,,,,,,,,,, In comparison with symptomatic, unruptured, large aneurysms, there are more difficulties associated with treatment of acute stage subarachnoid hemorrhage (SAH), such as ischemic complications that may occur either due to cerebrovascular spasm or due to lack of collateral vessels. There have been no detailed investigations of the perioperative complications occurring in the acute stage following PVS. Hence, this review was conducted to evaluate the risk factors associated with PVS for unclippable/uncoilable ruptured aneurysms.
Eligible related articles were identified by searching the PUBMED and SCIENCEDIRECT databases. The combination of search strings used for database searches included the terms “parent vessel occlusion OR parent artery occlusion” AND “acute subarachnoid hemorrhage” published until December 27, 2015. In addition, the journal “Interventional Neuroradiology” was electronically searched from November 1995 to April 2016.
All retrieved studies were scanned independently by two reviewers (Ge and Jin) to include only those studies that included patients with a ruptured aneurysm treated by PVS where their clinical outcomes had been reported. The following article types were excluded from the final analysis: (1) review studies; (2) patients with unruptured aneurysms; and, (3) articles or cases that had not reported clinical outcomes. Data on ruptured aneurysms treated by PVS in all subgroups were extracted independently by the same two authors who performed the literature search (Ge and Jin). Individual-level data was extracted from the included papers.
Hemorrhagic or ischemic complications were recorded by radiographic evidence. Clinical outcome was evaluated using the modified Rankin Scale (mRS). Clinical outcomes were divided into 'favorable outcomes ' (mRS, 0–3) and 'unfavorable outcomes' (mRS, 4–6). We divided these aneurysms into two groups, i.e., those in the acute phase (within 3 days); and, those in the chronic phase (later than 3 days).
All statistical analyses were conducted using the Statistical Package for the Social Sciences (IBM, New York). We subsequently conducted subgroup analyses to determine the factors associated with complications and and an unfavorable clinical outcome. Chi-square test was used for the analysis. P < 0.05 was considered to be statistically significant.
Systematic searches of the PUBMED, SCIENCEDIRECT databases and the journal “Interventional Neuroradiology” yielded 44, 785, and 203 results, respectively. After removing 3 duplicate papers, the titles and abstracts from the remaining 1010 studies were screened, and 19 potentially eligible studies for the systematic review were retained. The final 19 search results comprised 104 ruptured aneurysms in 104 patients [Table 1] treated by PVS.,,,,,,,,,,,,,,,,,, The age range was from 1 to 82 years (mean, 46 years). Seventy-nine (76.0%) PVS procedures were performed in the acute phase and 25 (24%) in the chronic phase after the ictus [Table 1]. Balloon test occlusion was performed in 12 patients and Mata's test (temporary occlusion of large vessels to assess the adequacy of collateral circulation) was performed in 17 patients to visualize collateral pathways. Bypass surgery was performed in 26 patients. The sacrificed vessels were 1 basilar artery and 1 vertebral artery, 25 internal carotid arteries, 4 middle cerebral arteries, 50 posterior cerebral arteries, 16 posterior inferior cerebellar arteries, and 7 superior cerebellar arteries.
Three patients (2.9%) had an intracranial hemorrhage, and 30 patients had an ischemic attack (29.0%). During the 14-month (range = 1–88 months) follow-up, there was no unfavorable outcome in the chronic group. In the acute phase, the unfavorable outcome rate for ICA sacrifice + bypass was 19.0%, for PCA sacrifice was 17.1%, for PICA sacrifice was 14.3%, and for SCA sacrifice was 28.6%.
The complication rate was higher for PVS in the acute phase (38.0% vs. 12.0%; P= 0.015). The unfavorable clinical outcome was found to be significant in the acute phase versus chronic phase (17.7% vs. 0%; P= 0.024). In the acute group, we detected no evidence that provocative tests (balloon occlusion test [BTO], Mata test), and bypass surgery could decrease the complication rate and the unfavorable outcome rate [Table 2]. The aneurysm size was reported in 38 acute phase cases; giant (>25) aneurysms were associated with a higher unfavorable outcome rate (66.7%) than large (10–25mm) [17.6%] and small (<10mm) [20%] aneurysms. Old age (>60 years) was not associated with an unfavorable outcome (P = 0.113), and the risk of morbidity associated with distal vessel (PCA + SCA + PICA) sacrifice was not lower than that associated with major vessel (ICA + BA + VA) sacrifice (P = 0.961).
PVS with trapping or proximal occlusion is an alternative treatment method for cerebral aneurysms in those cases in whom clipping or coiling with preservation of the parent artery is not possible.,,,, Most of these aneurysms are typically dissecting aneurysms, irrespective of whether their shape is “saccular” or “fusiform.” Spontaneous hemorrhagic intracranial dissection has an unfavorable prognosis and a high rebleeding rate. Although PVS effectively obliterates the aneurysm and prevents rebleeding, there is a potential risk of postoperative cerebral ischemia of the sacrificed arterial territory. PVS for acute stage SAH patients are associated with a high risk of complications and an unfavorable outcome. Vasospasm has been considered one of the major causes of cerebral ischemia after SAH. The present study revealed a 15.4% incidence of an unfavorable outcome in the bypass group, which was comparable to that observed in the PVS patients.,,, In addition, it is known that platelet adhesiveness is accelerated during the acute stage SAH,,, whereas cerebral perfusion pressure is decreased due to brain edema caused by the SAH., Accordingly, due to these very diverse reasons, despite the similarity of the operative technique for revascularization in acute stage SAH patients, it is clear that it is necessary to take into consideration that the risk of postoperative ischemic complications following revascularization was not lower than that in patients with direct PVS.
Balloon test occlusion may be a viable option to test whether or not vessel sacrifice will be tolerated. However, once a dissecting aneurysm has become symptomatic with hemorrhage, therapy is indicated; conduction of a balloon test occlusion only makes sense if a surgical bypass can be performed. Manual compression of the ipsilateral CCA is a less invasive technique for demonstrating the development of collateral circulation through the anterior communicating artery (ACoA) and posterior communicating artery (PCoA). The incidence of postoperative ischemic complications after a superficial temporal artery-middle cerebral artery (STA–MCA) bypass was higher than that after high-flow bypass in a study by Endo et al. They concluded that STA–MCA bypass should be applied in better grade SAH cases who have a sufficient collateral flow, which are cases with a low risk of cerebral ischemia. High-flow bypass is ideal for compensating for ICA sacrifice if the patients' condition tolerates the surgical stress of this procedure well. Despite the complex and time-consuming approach, an acute bypass with parent artery occlusion can achieve a favorable outcome in cases with unclippable/uncoilable ICA-ruptured aneurysms.
Distally located or branch artery aneurysms can be difficult to treat with embolization techniques that spare the parent artery. In these cases, PVS during aneurysm embolization may be inevitable [Figure 1] and [Figure 2]., The occlusion of the parent vessel for peripherally located and/or small-vessel aneurysms was not safer than the occlusion of the parent vessel for major vessel aneurysms. The risk of ischemic complications following parent vessel occlusion was, therefore, underestimated in the peripherally located and/or small-vessel aneurysms.,,,, Acute dissections may not have induced a sufficient leptomeningeal network of arteries to take over. Although this argument would favor a conservative approach once a dissection is found, acutely ruptured dissections are unstable and have a tendency to rebleed [Figure 1] and [Figure 2], with the rebleeding rate reported to be as high as 70%. The mortality rate of these rebleeds is as high as 50%. Hence, a decision on whether to treat these aneurysms conservatively or with PVS are both fraught with a high risk of developing ischemic complications.[20-22]
Limitations of this study
Certain limitations of this study need to be acknowledged. The number of included studies was relatively small. The aneurysm size was reported only in 38 cases (3.5% of this review). Ten studies were of a small size (comprised < 15 patients), and 4 were case reports. There may be a publication bias. The influence of the Hunt–Hess grades on the outcome was not analyzed because this information could often not be individually extracted from the articles.
This review serves as a reference for estimating the perioperative risk associated with parent vessel sacrifice as a treatment to prevent rebleeding in unclippable/uncoilable ruptured aneurysms. The complications and the unfavorable outcome rates associated with PVS for acutely ruptured aneurysms are high. The risk of ischemia developing with distal vessel sacrifice was not lower than that the risks associated with major vessel sacrifice in the acute phase of the SAH.
This work was funded by National Natural Science Foundation of China (grant No.81371314).
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
[Figure 1], [Figure 2]
[Table 1], [Table 2]