**6. Tips of direct surgery for recurrent aneurysms after endovascular coil embolization**

When choosing open clipping of a recurrent cerebral aneurysm after initial coil embolization, it is critical to confirm by preoperative cerebral angiography that there is sufficient space between the neck and the coil mass to allow for clip application. (**Figure 3a** and **b**) Toyota et al. reported that a remnant neck height of the aneurysm more significant than 2 mm is a prerequisite for surgery if the coil mass within the aneurysm is not removed [37]. Also, Waldron et al. reported that open cerebral aneurysm clipping without removing the coil mass in the aneurysm is unsuitable when the coil width and compaction height ratio exceeds 2.5 and a wedge angle greater than 90 degrees [38]. Confirming these findings by preoperative cerebral angiography is essential.

Perioperative stroke complications have been reported to be higher in patients undergoing intraoperative coil mass extraction [23]. Coil extraction was performed in 3/111 patients (2.7%), all of whom suffered a postoperative stroke [39]. The effects of coil embolization of cerebral aneurysms on the vital structure of the aneurysm, mother vessel, branches, and cranial nerves have been attributed to inflammatory and degenerative change mechanisms. A coil mass within the aneurysm causes inflammation and degeneration, resulting in extrusion of the coil mass outside the aneurysm, invasion of the surrounding vital structure, inflammatory adhesions, protrusion of the coil loop into the mother vessel, and scarring of the vessel wall. Surgical coil mass extraction in this condition is likely to cause steno-occlusion of the parent artery and damage to the vital structure. These can lead to postoperative stroke and neurological

#### **Figure 3.**

*(a) and (b): Schema of the morphological parameters of recurrent aneurysms after endovascular coil embolization. (a): The gray two-direction arrow indicates a coil width (C), and the black two-direction arrow indicates either a compaction height (H) or a remnant neck width (RNH). (b): The angle shown in the figure indicates a wedge angle. Aneurysms with RNH greater than 2 mm or a C/H ratio greater than 2.5 with a wedge angle greater than 90 degrees are unsuitable for direct clipping surgery without coil removal.*

*Perspective Chapter: Role of Direct Surgery for Recurrent Aneurysms after Endovascular Treatment DOI: http://dx.doi.org/10.5772/intechopen.112076*

#### **Figure 4.**

*a (upper) and b (lower): Schema of the neck clipping of the recurrence. (a): When a single aneurysm clip is applied to the aneurysm neck, atherosclerotic or inflammatory wall thickening (small black arrow) and coil loop inside (small white arrows) often prevent complete closure of the neck (thick white arrow). (b): The tandem clipping method, in which a fenestrated aneurysm clip is applied to the far side aneurysm neck, skipping the near side aneurysm neck, and an additional clip is used to close the near side aneurysm neck, is extremely useful in the above situation, as it provides complete closure of the neck.*

sequelae. Therefore, in the case of open clipping of recurrent cerebral aneurysms after initial coil embolization, coil mass extraction should be avoided as much as possible to ensure a safe procedure with a low rate of surgical complications.

Even in cases where preoperative imaging has shown sufficient space for clip application in the recurrent cerebral aneurysm, intraoperative findings may indicate that the room is smaller than expected during surgery. This phenomenon may be due to thrombus formation caused by coil mass in the aneurysm or thickening of the aneurysm wall due to inflammatory changes. In addition, a coil loop in the neck of the aneurysm may prevent complete occlusion of the neck when a single clip is applied (**Figure 4a**). The tandem clipping method has been reported to help deal with incomplete occlusion of cerebral clips due to stiff neck aneurysm walls and coil loops (**Figure 4b**) [40]. In this technique, a fenestrated aneurysm clip is applied to the far side aneurysm neck, skipping the near side aneurysm neck, and an additional clip is used to close the near side aneurysm neck. This technique is beneficial in narrow aneurysm neck spaces, stiff aneurysm neck walls, and the presence of coil loops in the neck, as complete occlusion of the aneurysm neck can be achieved without coil mass extraction. On the other hand, for large or giant cerebral aneurysms that recur after initial coil embolization and are at high risk for open aneurysm clipping, mother vessel occlusion with intracranial or extracranial bypass may be helpful [38, 40]. By this surgical strategy, direct manipulation of the aneurysm is no longer necessary, and it can be a safe treatment for recurrent cerebral aneurysms after coil embolization of deep locations like the upper basilar artery system or when there is already a high mass effect on the vital structures.

### **7. Illustrative case presentations**

**Case 1:** A 65-year-old woman presented with Hunt and Kosnik grade 1, Fisher group 3 subarachnoid hemorrhage. Her digital subtraction angiography (DSA) revealed a right internal carotid artery-posterior communicating (IC-Pcom) artery aneurysm. She underwent coil embolization. The aneurysm was completely obliterated. Her postoperative course was uneventful, and she was discharged home without a neurological deficit. Six months after initial treatment, follow-up DSA showed the remarkable recurrence of the aneurysm with coil compaction (**Figure 5a**). Thus, she underwent additional clipping surgery for the recurrent IC-Pcom aneurysm.

**Intraoperative findings** (Video 1 https://1drv.ms/f/s!AnNEb0cDdygmSdOw3kIA3vy\_9kf?e=pgxew1): Coil mass inside the aneurysm dome were seen through not only the wall of the dome but also through the wall of the neck. First, we applied a straight-type titanium clip, but the tip slipped toward the Pcom, so we removed this clip. Then, we applied a fenestrated Elgiloy clip in partial occlusion of the far side aneurysm neck. Indocyanine-green video angiography (ICG-VA) showed patency of ICA, Pcom, and anterior choroidal artery and nonfilling of the aneurysm. We added a straight Elgiloy clip in parallel fashion to secure the complete obliteration of the aneurysm.

Postoperative CT showed no complication and complete obliteration of the aneurysm (**Figure 5b** and **c**). Her postoperative course was uneventful, and she was discharged home without a neurological deficit.

**Case 2:** A 63-year-old woman presented with Hunt and Kosnik grade 2, Fisher group 3 subarachnoid hemorrhage. Her DSA revealed a right IC-Pcom artery aneurysm. She underwent coil embolization. The aneurysm was completely obliterated. Her postoperative course was uneventful, and she was discharged home without a neurological deficit. Forty-one months after initial treatment, follow-up DSA showed the remarkable recurrence of the aneurysm with fundal migration (**Figure 6a**). Thus, she underwent additional clipping surgery for the recurrent IC-Pcom aneurysm.

Intraoperative findings (**Video 2** https://1drv.ms/f/s!AnNEb0cDdygmSdOw3kIA3vy\_9kf?e=FQyE2p): Coil mass inside the aneurysm dome were seen through the dome's wall. And fundal migrated coil loops compressed the right oculomotor nerve. We applied a straight-type titanium clip to the neck of the aneurysm and supposed this to be complete obliteration. We incised the dome with microscissors to release the oculomotor nerve from compression by the coil loops. Major bleeding was seen from the incised aneurysm dome. To stop bleeding, we applied a temporary clip to the proximal ICA. The bleeding was controlled completely. Then we applied an additional fenestrated clip and removed the temporary clip.

Postoperative CT showed a thin epidural hematoma and complete aneurysm obliteration (**Figure 6b** and **c**). Her postoperative course was uneventful, and she was discharged home without a neurological deficit.

#### **Figure 5.**

*a-c: The imaging studies of illustrative case 1. (a): Follow-up DSA (lateral view of right ICGA) 6 months after initial coil embolization showed remarkable recurrence of the treated IC-Pcom aneurysm (white arrow). (b) and (c): Postoperative plain CT and CT angiography showed no complication and complete obliteration of the aneurysm.*

*Perspective Chapter: Role of Direct Surgery for Recurrent Aneurysms after Endovascular Treatment DOI: http://dx.doi.org/10.5772/intechopen.112076*

**Figure 6.**

*a-c the imaging studies of illustrative case 2. (a) Follow-up DSA (lateral view of right ICGA) 41 months after initial coil embolization showed remarkable recurrence of the treated IC-Pcom aneurysm (white arrow). (b) and (c) postoperative plain CT and CT angiography showed thin epidural hematoma and complete aneurysm obliteration.*

**Case 3:** A 43-year-old man presented with Hunt and Kosnik grade 3, Fisher group 3 subarachnoid hemorrhage. His DSA revealed a left IC-Pcom artery aneurysm. He underwent coil embolization. The aneurysm was completely obliterated. His postoperative course was uneventful, and he was discharged home without a neurological deficit. Eighteen months after initial treatment, follow-up DSA showed the remarkable recurrence of the aneurysm with regrowth, and he underwent additional stentassisted coil embolization for the aneurysm. However, 30 months after the second treatment, follow-up MRI and DSA revealed the recurrence as a partially thrombosed

#### **Figure 7.**

*a-f: The preoperative (a-c) and postoperative (d-f) imaging studies of illustrative case 3. (a) Silent MRA 30 months after the second treatment. (b) T1-weighted MRI. (c) 3D rotational angiography. The imaging studies showed recurrent partially thrombosed giant left IC-Pcom aneurysm (white arrow). (d) Postoperative diffusionweighted MRI. (e) and (f): Postoperative DSA anterior-posterior and lateral view. The imaging studies showed no ischemic complication and complete aneurysm obliteration with preservation of normal arteries.*

giant aneurysm (**Figure 7a**–**c**). Thus, he underwent additional clipping surgery for the recurrent IC-Pcom aneurysm.

Intraoperative findings (Video 3 https://1drv.ms/v/s!AnNEb0cDdygmSsspZ6yOvo4Mle1?e=hlee0e): The stent was inserted in the left proximal intracranial ICA, but proximal control at this site was confirmed feasible. Left Pcom origin was observed at the proximal neck of the aneurysm. Coil mass inside the aneurysm dome and stent strut were seen through the wall of the dome and ICA. The left anterior choroidal artery and perforators from Pcom firmly adhered to the dome of the aneurysm. The adhesion was detached with sharp dissection. While performing temporary occlusion in the proximal intracranial ICA, first, we applied a fenestrated titanium clip in partial occlusion of the far side aneurysm neck. ICG-VA revealed the residual flow into the aneurysm through the near side of the neck of the aneurysm. We added a straight titanium clip in a parallel fashion to secure the complete obliteration of the aneurysm. ICG-VA showed complete obliteration of the aneurysm and preservation of the parent artery and branches.

Postoperative imaging studies showed complete aneurysm obliteration without complication (**Figure 7d**–**f**). His postoperative course was uneventful, and he was discharged home without a neurological deficit.
