Low-angled microcatheter approach for coil embolization of the anterior choroidal artery aneurysm

Technical Approaches for Coil Embolization of Unruptured Small Anterior Choroidal Artery Aneurysms: A Focus on Anatomical Flow Preservation of the Anterior Choroidal Artery

The anterior choroidal artery (AChA) supplies the corticospinal tract related to the motor function of the upper and lower limbs. Aneurysms arising at the AChA are not common and exhibit various patterns of involvement of the AChA. Hence, managing an AChA aneurysm poses a high risk of neurological deficits. We report technical issues related to the outcome of coil embolization for unruptured AChA aneurysms. We obtained Institutional Review Board approval for this study. In the past 2 years, 18 consecutive patients (6 males and 12 females, aged 32-68) with unruptured AChA aneurysms were treated using embolization. We present technical details, pre- and post-procedural patient statuses, angiographic outcomes, and recurrence during a mean follow-up period of 12 months (range 3-25). The patients with AChA (n=18) underwent stent-assisted coiling (n=14), coiling (n=2), or stenting only (n=2). The technical strategy for aneurysm embolization included a low-lying approach into the aneurysm, stent-strut abutting (protecting) coil framing to block inflow and avoid compromising AChA flow, and direct intra-aneurysmal angiography via a microcatheter. Angiographic results showed complete occlusion (n=11), neck remnant (n=5), and sac remnant (n=2). During the follow-up, there were 2 recurrences, and 1 of them required a re-procedure. All patients showed no change in clinical status (modified Rankin scale score=0) and did not experience any ischemic or hemorrhagic events during the follow-up period. AChA aneurysms can be managed through embolization using various techniques. Such technical concepts may enhance the safety and improve the outcomes of AChA aneurysm embolization.

Positional Relationship between Two Microcatheters according to the Navigation Sequence within the Curved Vessel in Neuroendovascular Procedures

Objective  In neuroendovascular treatment, there are many opportunities to guide multiple catheters into the intracranial blood vessels. We report the relationship between two microcatheters according to the guiding order with experimental in vitro studies. Materials and Methods  We hypothesize that in a bent blood vessel such as a paraclinoid region of the internal carotid artery, the catheter that was first guided tended to pass through the inside, and the catheter that was guided later tended to pass through the outside. The in vitro verification was performed using a microcatheter and a balloon catheter in a silicone vascular aneurysmal model. Results  As a result, it was found that the two catheters were arranged according to our hypothesis. This finding was also observed during the actual operation of balloon-assisted coil embolization. Conclusion  The positional relationship between the two catheters according to the navigation order is very important, in particular during balloon-assisted coiling and stent-assisted coiling via a jailed microcatheter.

Positional Relationship between Two Microcatheters according to the Navigation Sequence within the Curved Vessel in Neuroendovascular Procedures

In neuroendovascular treatment, there are many opportunities to guide multiple catheters into the intracranial blood vessels. We report the relationship between two microcatheters according to the guiding order with experimental in vitro studies. We hypothesize that in a bent blood vessel such as a paraclinoid region of the internal carotid artery, the catheter that was first guided tended to pass through the inside, and the catheter that was guided later tended to pass through the outside. The in vitro verification was performed using a microcatheter and a balloon catheter in a silicone vascular aneurysmal model. As a result, it was found that the two catheters were arranged according to our hypothesis. This finding was also observed during the actual operation of balloon-assisted coil embolization. The positional relationship between the two catheters according to the navigation order is very important, in particular during balloon-assisted coiling and stent-assisted coiling via a jailed microcatheter.

Physiologic Flow Diversion Coiling Technique for Wide-Necked Aneurysms with an Asymmetric Bidirectional Flow at the Aneurysm Neck

PURPOSE

Wide-necked aneurysms in the circle of Willis (CoW) are prone to recur due to reciprocal bidirectional flow. We present a novel concept of coil embolization to prevent recurrence that uses physiologic flow diversion at the CoW.

MATERIALS AND METHODS

We enrolled 14 patients (15 aneurysms) who underwent aneurysm coiling for wide-necked aneurysms with asymmetric bidirectional inflow into the aneurysm. Four patients had recurrent aneurysms after coiling. The concept of physiologic flow diversion included obliterating antegrade flow into the aneurysm sac as well as opposite CoW flow by performing compact coil packing with intentional protrusion out of the aneurysm neck to the communicating part.

RESULTS

Fifteen aneurysms, including 4 recurrent aneurysms, in an anterior communicating artery (n=7), posterior communicating artery (n=5), and tip of the basilar artery (n=3) were treated with coil embolization (n=10) and stent-assisted coiling (n=5). All aneurysms had a wide neck, and the mean largest diameter was 9.0 mm. The mean packing density was 45.1%. Twelve aneurysms were completely occluded, and 3 aneurysms had tiny residual neck remnants. There was neither a neurological event nor recurrence during the mean 12.5 months of follow-up.

CONCLUSION

Wide-necked aneurysms at the CoW tend to recur. As a strategy to prevent a recurrence, physiologic flow diversion can be an option in treating wide-necked aneurysms in the CoW.

Outpatient Day-Care Management of Unruptured Intracranial Aneurysm: A Retrospective Cohort Study

OBJECTIVE

This study aimed to assess the outcomes of outpatient day-care management of unruptured intracranial aneurysm (UIA), and to present the risks associated with different management strategies by comparing the outcomes and adverse events between outpatient day-care management and management with longer admission periods.

MATERIALS AND METHODS

This retrospective cohort study used prospectively registered data and was approved by a local institutional review board. We enrolled 956 UIAs from 811 consecutive patients (mean age ± standard deviation, 57 ± 10.7 years; male:female = 247:564) from 2017 to 2020. We compared the outcomes after embolization among the different admission-length groups (1, 2, and ≥ 3 days). The outcomes included pre- and post-modified Rankin Scale (mRS) scores and rates of adverse events, cure, recurrence, and reprocedure. Events were defined as any cerebrovascular problems, including minor and major stroke, death, or hemorrhage.

RESULTS

The mean admission period was 2 days, and 175 patients (191 aneurysms), 551 patients (664 aneurysms), and 85 patients (101 aneurysms) were discharged on the day of the procedure, day 2, and day 3 or later, respectively. During the mean 17-month follow-up period (range 6-53 months; 2757 patient years), no change in post-mRS was observed compared to pre-mRS in 99.6% of patients. Cure was achieved in 95.6% patients; minimal recurrence that did not require re-procedure occurred in 3.5% patients, and re-procedure was required in 2.3% (22 of 956) patients due to progressive enlargement of the recurrent sac during follow up (mean 17 months, range, 6-53 months). There were eight adverse events (0.8%), including five cerebrovascular (two major stroke, two minor strokes and one transient ischemic stroke), and three non-cerebrovascular events. Statistical comparison between groups with different admission lengths (1, 2, and ≥ 3 days) revealed no difference in the outcomes.

CONCLUSION

This study revealed no difference in outcomes and adverse events according to the admission period, and suggested that UIA could be managed by outpatient day-care embolization.

Microcatheter Stabilization Technique Using Partially Inflated Balloon for Coil Embolization of Paraclinoid Aneurysms

PURPOSE

Coil embolization of paraclinoid aneurysms should be simple, safe, and effective considering the benign nature of the aneurysm. Here, we present a microcatheter stabilization technique using a partially inflated balloon for the treatment of paraclinoid aneurysms.

MATERIALS AND METHODS

This retrospective study included 58 patients who underwent balloon-assisted coiling (BAC) for unruptured paraclinoid aneurysms at a tertiary neuro-intervention center between January 2019 and March 2020. We applied a technique to stabilize the microcatheter's position using the modified BAC technique in paraclinoid aneurysms showing various projections around the ophthalmic curve of the internal carotid artery. The basic concept of the technique is to place a partially inflated balloon just distal to the aneurysm neck and support the distal curve of the microcatheter using the proximal bottom of the balloon. Immediate radiological outcomes were analyzed, and clinical outcomes were evaluated with modified Rankin Scale (mRS) scores.

RESULTS

The BAC was successfully performed in 51 of 58 patients (88%). We treated the remaining 7 patients by switching to stent-assisted coiling. We obtained a 37% mean packing density resulting in favorable occlusion in all 58 aneurysms (complete occlusion in 35 and residual neck in 23). There were no intraprocedural thromboembolic or hemorrhagic events except one that revealed an asymptomatic infarction after the procedure (1.7%). Magnetic resonance angiography follow-up was performed in 37 patients at an average of 11.8 months, in which 11 minor recurrences (29.7%) were found. There was no major recurrence nor retreatment. The mRS score was 0 in all patients during a mean follow-up of 17.7 months (range, 12-25 months).

CONCLUSION

The modified balloon-assisted coiling technique using a partially inflated balloon was safe and effective and could serve as an option for treating paraclinoid aneurysms.

A New Classification of Anterior Choroidal Artery Aneurysms and Its Clinical Application

Background and Purpose: The aim of this study was to compare the different subtypes of anterior choroidal artery (AChoA) aneurysm based on a new classification and to analyze the risk factors according to individual endovascular treatment (EVT).

Methods: In the new classification, AChoA aneurysms are classified into independent type (I type) and dependent type (II type) based on the relationship between the AChoA and the aneurysm. II type aneurysms have three subtypes, IIa (neck), IIb (body), and IIc (direct). We retrospectively analyzed 52 cases of AChoA aneurysm treated in our center between 2015 to 2019. There were 13 (25.0%) I type aneurysms, 24 (46.2%) IIa aneurysms, 15 (28.8%) IIb aneurysms, and no IIc type; 28 cases had a subarachnoid hemorrhage. According to our preoperative EVT plan for the different subtypes: II type should achieve Raymond-Roy Occlusion Class 1 (RROC 1) where possible. To protect the AChoA, it is best to preserve the neck of the IIa type aneurysms (RROC 2), and RROC 3 is enough for IIb type.

Results: Ten asymptomatic cases with minimal aneurysms were treated conservatively. Of the other cases, 42 were treated with individualized EVT (26 with a simple coil, 6 with balloon-assisted coiling, 7 with stent-assisted coiling, and 3 by flow diverter. Different subtypes had different RROC (Z = 14.026, P = 0.001). IIb type aneurysms (χ² = 7.54, P = 0.023) were one of the factors related to temporary or permanent AChoA injury during surgery. Overall, two patients (IIa = 1, IIb = 1) developed contralateral hemiparesis.

Conclusions: The new classification diagram clearly shows the features of all types of AChoA aneurysm and makes EVT planning more explicit. The II type (particularly IIb) was a potential risk factor for AChoA injury.

Stent-Assisted Coil Embolization of MCA Bifurcation Aneurysms at a Hypoplastic M1 Branch by Use of Hook Technique

BACKGROUND

We describe the Hook technique enabling coil embolization in unfavorable M1 bifurcation aneurysms and analyze the morphologic variations in M1 bifurcation to evaluate how often such aneurysms can be seen.

METHODS

Among 42 MCA aneurysms treated by stent-assisted coil embolization, aneurysms arising at the acute-angled hypoplastic M1 branch (n = 14) were treated by the Hook technique, in which a short stent was deployed only to protect the aneurysm neck after microcatheter selection of the hypoplastic M2, followed by subsequent coiling of the aneurysm. Outcome was evaluated, including Raymond classification, coil packing density, final modified Rankin Scale (mRS), and recurrence. Separately, 100 middle cerebral artery (MCA) bifurcation aneurysms were analyzed to assess the proportion of such unfavorable aneurysms.

RESULTS

Procedural success of the Hook technique was obtained in 13 of 14 patients (93%). A mean packing density of 30% was achieved. Magnetic resonance angiographic follow-up at a median 4 months (range, 1-26 months) showed complete occlusion in 11 patients and residual neck filling in 3 patients. There was no clinical event (mRS = 0) over a median 17 months (range, 2-26 months) of clinical follow-up. One patient had a thrombotic occlusion during the procedure, which was resolved after tirofiban infusion, without evidence of an infarct or deficit. Of the 100 MCA bifurcation aneurysms, aneurysm arising in asymmetric hypoplastic M2 division was the most common type (48%).

CONCLUSIONS

The Hook technique enabled stent-assisted coiling of M1 bifurcation aneurysm with extension along the asymmetric hypoplastic M2 division and also securing the M2 branch.

Loop microcatheter technique for coil embolization of paraclinoid aneurysms

BACKGROUND

Although paraclinoid aneurysms do not exhibit a high risk of rupture, coil embolization is not always easy because of unstable microcatheter position. We present a technique that allows a stable microcatheter position for coil embolization of paraclinoid aneurysms.

METHODS

We enrolled 34 consecutive patients who underwent coil embolization for paraclinoid aneurysms. A loop of distal microcatheter was shaped based on three-dimensional rotational angiography. The basic concept is to keep the proximal loop abutting the opposite wall of the aneurysm while using the distal loop for coiling. Then, a proximal curve was made to accommodate the shape of the carotid siphon, which may decide the direction of the loop. Stent-assisted coil embolization was performed in 19 wide-necked aneurysms. Immediate radiological outcomes were analyzed with Raymond classification and clinical outcomes were evaluated with modified Rankin Scale (mRS) scores.

RESULTS

Satisfactory occlusion of aneurysm was achieved in 94.1% (32/34) of patients with a Raymond score of 1 or 2. Packing density of ≥ 31% was achieved in 71% (24/34) of patients. No significant differences were observed between stent-assisted coiling and coiling-only groups. Follow-up magnetic resonance angiography and/or angiogram showed stable coil position, except in one patient with tiny recurrence (from Raymond scores 1 to 2) that did not require retreatment at the 6-month follow-up. mRS scores of 0-1 were obtained in all patients at 6 months.

CONCLUSIONS

Loop microcatheter technique allowed safe and stable coil packing for paraclinoid aneurysms. The same procedural concept is also being used for aneurysms in other vascular territories.