Endovascular treatment has become the first choice for intracranial aneurysm. The treatment of wide-necked and irregular aneurysms in anterior cerebral circulation is still a challenge because of the coil instability and a high recurrence rate . The improvement of devices and techniques extended the usage of endovascular coiling, such as stent- or balloon- assisted coiling, double microcatheter technique and flow diverter [2–4,12]. Those could be used in wide-necked or irregular aneurysms. But there are still some debates on the stent- or balloon-assisted coiling for ruptured aneurysms in acute stage.
Stent-assisted coiling was used to treat unruptured wide-necked aneurysms. The deployment of stent can protect coil from protruding into parent artery. Additionally, it can reduce the recurrence rate [16–17]. However, the deployment of stent in acute stage may incur more complications such as in-stent thrombosis [7,18,19]. Fan et al. reported that thrombosis occurred in 15.9% patients after stent-assisted coiling versus 3.8% after coiling alone for ruptured communicating artery aneurysms . The usage of antiplatelet medications may increase the rate of rebleeding, especially in patients who require EVD, craniotomy or ventriculoperitoneal shunt [7,20,21]. Additionally, it is difficult to navigate the stent-delivery catheter in tortuous and small vessels. There are many reports of flow diversion treatment for intracranial aneurysms recently. But the occlusion of aneurysms may require weeks or months and the rebleeding is not excluded .
In 1997, Moret et al. firstly reported the balloon remodeling technique . Balloon-assisted coiling is an alternative method for wide-necked or irregular aneurysms. It blocks the blood flow temporarily, which decreases the risk for rupture and protects the aneurysm neck. It may increase the packing density. There is no need to taking antiplatelet medications periprocedurally. However, delayed coil migration was reported insome cases . It may also incur bleeding and thrombosis events [25,26]. Sluzewski et al. reported that the procedure-related complications were higher in balloon-assisted coiling (14.1%) compared with those in coiling alone (3%) . Additionally, it is difficult to navigate into tortuous and small vessels. Therefore, balloon-assisted coiling was not supported by some authors [9,25].
In 1998, Baxter et al. firstly reported the double microcatheter technique . Since then, there were some reported about double microcatheter technique [11–13] The advantages of double microcatheter technique are that there is no need to block the blood flow and take antiplatelet medications. The procedure is relatively simple compared with stent- or balloon-assisted coiling when it is used in wide-necked or irregular aneurysms. The two microcatheter had better to be shaped with different curve in order to get into different portion and form a stable frame. The advancement of the second microcatheter may incur the migration of the first microcatheter. Durst et al. reported three intraprocedural ruptures (3%) . One of them occurred in an unruptured aneurysm because the microcatheter perforated the aneurysm dome. It is important to take care of the tension of the first microcatheter during the advancement of the second microcatheter. In our cases, the first coil was usually advanced fully or partially into the aneurysm without detachment before the advancement of the second microcatheter. The risk for rupture might decrease because the buffering of the first coil. No intraprocedural rupture occurred in our cases.
Double microcatheter technique can be used in a variety of aneurysms. Firstly, it can be used in wide-necked aneurysms. Two shaped microcatheters with different curve are navigated into different portion of aneurysms to form a stable frame. It was reported in several reports [11,12]. For wide-necked aneurysms with creep growth, we firstly used double parallel framing coils technique [Fig. 1]. Secondly, it can be used in aneurysms with daughter sac [Fig. 2]. One microcatheter can be navigated into the daughter sac if it is not difficult and another is navigated into aneurysm sac. The daughter sac is usually the bleeding point. It can decrease the risk for rebleeding if the daughter sac can be packed densely. Kim et al reported one case with fusiform aneurysm in the supraclinoid segment with a daughter sac . The patient received selective coiling of daughter sac. Thirdly, it can be used in branch-incorporated aneurysms [Fig. 3]. One microcatheter was placed at the orifice of branch in order to protect it from being occluded. Another microcatheter was used to coil the aneurysm. Kim et al. reported this technique in 2018 . Fourthly, it can be used in enlongated aneurysms. One microcatheter is navigated deeply into the aneurysm and another close to the neck . Additionally, it can be used in parent artery occlusion for ruptured vertebral artery aneurysms by bilateral vertebral artery approach. But most vertebral artery aneurysms are dissecting ones. In this series of cases, the ruptured aneurysms in posterior cerebral circulation were excluded.
The procedure of double microcatheter technique is simple. There are lower procedure-related complications in patients treated by double microcatheter technique than those treated by stent-assisted coiling . The recurrence rate may be higher for patients treated with double microcatheter technique than those treated by stent-assisted coiling. The procedure-related complications are about 20% for patients receiving stent-assisted coiling with ruptured aneurysms [21,29]. The data for procedure-related complications in ruptured aneurysms treated by double microcatheter are rare. Yoon et al reported 56 patients treated by double microcatheter technique . The procedure-related complications and permanent complications rate were 12.5% and 1.8%. The recurrence and retreatment occurred in 21 patients (56.8%) and 5 patients (13.5%). 64.3% of patients obtained favorable outcome at discharge. In our series of patients, the procedure-related complications and permanent complications rate were 8.5% and 3.7%. The recurrence and retreatment rates are 34.1% and 15.9%. The favorable outcomes were obtained in 75.6% (62/82) of the whole patients at discharge. We found that packing density was risk factor for recurrence. Hunt-Hess grade and suffering from EVD or craniotomy were risk factors for clinical outcome at discharge. Some authors thought that there was no significant difference in recurrence rate among patients treated by double microcatheter technique, stent- and balloon- assisted coiling [13,30]. More recurrence may be found with the extension of time. Retreatment may be chosen with lower morbidities. The physician must balance the complications and recurrence.
There are some limitations of this study. There is a selective bias because this is a retrospective and non-randomized study. The number of patients was limited. Some patients were lost to follow up because of poor outcome or change of contact information, especially angiographic follow-up.