Three cases of aneurysms were evaluated in this study: 2 were ruptured aneurysms and the other showed imminent rupture signs of third cranial nerve palsy. They were treated using the endovascular procedure with the parent artery complex coil protection technique. We chose not to use intracranial stents in these emergency cases because we could not start the preoperative antiplatelet administration. The procedures and techniques were successful in all the cases. There were no related complications, such as thrombosis or bleeding. Only 1 patient had a postoperative spotty hyperintense area on diffusion-weighted imaging (DWI) but without symptoms. The postoperative outcomes of all the cases were good.

All procedures were performed under general anesthesia. The femoral artery was punctured in the inguinal region on either side. Using an 8 Fr long sheath in all patients, an 8 Fr RoadMaster 80 cm (Goodman, Aichi, Japan) was placed in the common carotid artery on the treatment side as a guide. For the inner catheter of the 6 Fr Cerulean DD6 118 cm (Medikit, Tokyo, Japan), a 4.2 Fr Fubuki 130 cm (Asahi Intecc, Aichi, Japan) was used, and a head-shaped DD6 was advanced into the C3/4 portion of the internal carotid artery.

We performed the parent artery complex coil protection technique as follows. For step 1, the first microcatheter was introduced into the aneurysmal sac, but the attempt to put the first framing coil failed due to coil protrusion (Fig. 1A). For step 2, the second microcatheter was introduced into the parent artery or near the orifice of the branch artery. A framing coil was partially deployed from the first microcatheter, and a protection complex coil was deployed from the second microcatheter to prevent the first framing coil from protrusion to the parent artery and side branches. The entire length of the framing coil was successfully inserted into the aneurysm sac with the help of a protective coil (Fig. 1B). For step 3, the protection coil was gently withdrawn to confirm the stability of the framing coil and blood flow after the first framing coil insertion (Fig. 1C). For step 4, the coil embolization was continued from the first microcatheter till the end, and the protection coil was essentially inserted into the aneurysmal sac.

An 84-year-old female patient had right third cranial nerve palsy and was urgently admitted for treatment of a right internal carotid-posterior communicating artery aneurysm. Coil embolization was performed the day after admission. Digital subtraction angiography (DSA) revealed a wide-neck internal carotid-posterior communicating artery aneurysm, which was 6 mm in dome height and 5 mm in neck width. The aneurysm aspect ratio was 1.2. The posterior communicating artery (Pcom) was incorporated into the aneurysm neck (Fig. 2A, B). We initially attempted to treat the aneurysm using a simple technique with the Target 360 XL Soft 5 mm×15 cm (Stryker-Neurovascular, Kalamazoo, MI, USA) from the first microcatheter in the aneurysmal sac but failed to preserve the Pcom due to coil protrusion. We introduced the second microcatheter into the internal carotid artery just in front of the aneurysm and attempted parent artery complex coil protection with the Target 360 Ultra 4 mm×8 cm. The protection coil size (4 mm) was decided by the total length of the internal carotid artery diameter (2.5 mm) and the Pcom diameter (1.5 mm). First, the framing coil was partially inserted into the sac without protrusion. After the protection coil was partially inserted at the aneurysmal neck near the Pcom, the first framing coil was inserted completely, and optimal framing was achieved (Fig. 2C). The stability of the framing coil and preservation of the incorporated branch were confirmed after withdrawing the protection coil, which was also inserted into the sac as a filling coil. Finally, 5 coils with a total length of 41 cm were inserted into the aneurysm (Fig. 2D, E). Magnetic resonance DWI images at 7 days after the procedure showed spotty hyperintense areas, but there were no symptoms (Fig. 2F).

A 76-year-old male patient was urgently admitted for a Hunt and Kosnik Grade 5 subarachnoid hemorrhage caused by rupture of the basilar artery (BA) tip aneurysm, and emergency coil embolization was performed the day after admission.

DSA revealed a very wide-neck BA tip aneurysm, which was 11 mm in dome height and 7 mm in neck width. The aneurysm aspect ratio was 1.57. The bilateral posterior cerebral arteries were incorporated into the aneurysm neck (Fig. 3A, B). Stent-assisted coiling could not be performed because of the rupture. Therefore, we initially attempted to treat the aneurysm using a simple technique and a standard double catheter technique but failed to make the first framing because of the strong inflow/outflow jet.

Therefore, we introduced the first microcatheter in the center of the aneurysmal dome, followed by the second microcatheter at the BA tip with 1 turning in the aneurysmal dome (Fig. 3D).

The protection coil, the Target XL 360 Soft 7 mm×20 cm, was partially inserted from the second microcatheter using the parent artery complex coil protection technique to make the framing at the upper side of the aneurysmal dome after inserting some loops of the framing coil, the Target XL Helical 6 mm×20 cm (Fig. 3C). According to the total length (12.5 mm) of the dome height (11 mm) and posterior cerebral arteries diameter (1.5 mm), the protection coil size (7 mm) was decided after partially inserting the framing coil (6 mm). The first framing coil was inserted completely under the protection coil, and the stability of the framing coil was confirmed after withdrawing the protection coil (Fig. 3D). With this coil protection, 7 coils, with a total length of 84 cm, were inserted into the aneurysm (Fig. 3E, F). Magnetic resonance DWI image at 8 days after the procedure showed no ischemic area.