Could the types of paraclinoid aneurysm be used as a criterion in choosing endovascular treatment? Neuro-radiologists' view

Navigating complexity: a comprehensive review of microcatheter shaping techniques in endovascular aneurysm embolization

The endovascular intervention technique has gained prominence in the treatment of intracranial aneurysms due to its minimal invasiveness and shorter recovery time. A critical step of the intervention is the shaping of the microcatheter, which ensures its accurate placement and stability within the aneurysm sac. This is vital for enhancing coil placement and minimizing the risk of catheter kickback during the coiling process. Currently, microcatheter shaping is primarily reliant on the operator's experience, who shapes them based on the curvature of the target vessel and aneurysm location, utilizing 3D rotational angiography or CT angiography. Some researchers have documented their experiences with conventional shaping methods. Additionally, some scholars have explored auxiliary techniques such as 3D printing and computer simulations to facilitate microcatheter shaping. However, the shaping of microcatheters can still pose challenges, especially in cases with complex anatomical structures or very small aneurysms, and even experienced operators may encounter difficulties, and there has been a lack of a holistic summary of microcatheter shaping techniques in the literature. In this article, we present a review of the literature from 1994 to 2023 on microcatheter shaping techniques in endovascular aneurysm embolization. Our review aims to present a thorough overview of the various experiences and techniques shared by researchers over the last 3 decades, provides an analysis of shaping methods, and serves as an invaluable resource for both novice and experienced practitioners, highlighting the significance of understanding and mastering this technique for successful endovascular intervention in intracranial aneurysms.

Endovascular Treatment and Microsurgical Clipping for the Management of Paraclinoid Intracranial Aneurysms: A Systematic Review and Meta-Analysis

OBJECTIVE

We aimed to compare the efficacy and safety of microsurgical clipping versus endovascular treatment (EVT) for paraclinoid aneurysms.

METHODS

A systematic search for studies including patients with paraclinoid aneurysms treated with a microsurgical or endovascular technique was conducted in 6 databases from inception to February 2022. Efficacy outcomes included complete angiographic occlusion at last follow-up, favorable functional outcome, and recurrence of the aneurysm. For safety, we assessed a composite of intraoperative and postoperative complications. Data were pooled using a random-effects model.

RESULTS

A total of 95 studies including 6711 patients, 3029 in the surgical group and 3682 in the EVT group were found. Pooled rates of complete occlusion were 94% (95% CI 91%-96%; I2 = 0%) in the surgical group and 69% (95% CI 63%-74%; I2 = 79%) in the EVT group, respectively. The favorable functional outcome rate was 86% (95% CI 76%-92%; I2 = 72%) with surgical treatment and 95% (95% CI 92%-97%; I2 = 61%) with EVT. The rate of aneurysm recurrence with surgical treatment was 1% (95% CI 0%-4%; I2 = 0%) and 12% (95% CI 9%-16%; I2 = 57%) with EVT. The composite safety outcome rate in the surgical group was 24% (95% CI 18%-30%; I2 = 90%) and 10% (95% CI 8%-13%; I2 = 71%) in the EVT group.

CONCLUSIONS

Our findings suggest that microsurgical clipping seems to have a higher efficacy than EVT in terms of angiographic occlusion and aneurysm recurrence; however, EVT seems to be safer in terms of intraoperative and postoperative complications. Considering the heterogeneity and low-level evidence of the data available, further prospective randomized studies are warranted to confirm our findings.

Simple and Reproducible Microcatheter Shaping Method for Coil Embolization of Medially-directed Paraclinoid Internal Carotid Artery Aneurysms

Objective

It is important to guarantee intra-aneurysmal stability of microcatheters during coil embolization. We developed a simple and reproducible microcatheter shaping method for medially-directed paraclinoid internal carotid artery aneurysms.

Methods

An injection needle cap was used to make a smooth curve on the mandrel, which was first wound around the back end of the cap to create a primary curve. Next, a secondary curve was created using near the tip of the cap. Thus, a two-dimensional (2D), pigtail-shaped mandrel with a two-stage curve was created. The pigtail-shaped mandrel was inserted from the tip of a straight microcatheter and heat-shaped using a heat gun. Lastly, a microcatheter having a curve whose tip was approximately 6 mm longer than that of the preshaped J was created. We evaluated the ease of navigating the microcatheter into the aneurysm and its stability during coil embolization.

Results

In all, 34 consecutive medially-directed paraclinoid internal carotid artery aneurysms were treated using the shaped catheters. It took 50-300 seconds (intermediate value: 90 seconds) from inserting the microcatheter with a microguide wire to navigate and place it into an aneurysm. There were no cases that required reshaping of the microcatheters during navigation into the aneurysm. There were no cases that resulted in kickback of the microcatheters from the aneurysm during coil placement, and microcatheter stability was good until the end of the procedure. In all, 12 cases required the balloon-assisted technique and three cases required stent-assisted coiling. The angiographic outcomes immediately after embolization were as follows: 25 cases (73.5%) with complete occlusion; 3 cases (8.8%) with dome filling; and 6 cases (17.6%) with a neck remnant. There were no perioperative complications.

Conclusion

The shaping method with a pigtail-shaped mandrel using an injection needle cap is simple and reproducible, and is useful for medially-directed paraclinoid internal carotid artery aneurysms.

Limited Indications for Clipping Surgery of Paraclinoid Aneurysm Based on Long-Term Visual Morbidity

OBJECTIVE

Clipping of paraclinoid aneurysm is still challenging because of poor visual morbidity. The extradural temporopolar approach was applied to clip paraclinoid aneurysms, with the expectation of reducing visual morbidity. Factors related to poor visual morbidity were evaluated, to assess the results for clipping of paraclinoid aneurysms.

METHODS

A series of 40 unruptured paraclinoid aneurysms in 38 patients were clipped via extradural temporopolar approach. Preoperative and postoperative states of visual cognitive function and radiological outcomes were investigated. Aneurysms were classified into dorsal type or non-dorsal type, and small (<9 mm) or not-small (≥9 mm), respectively, to identify factors correlated with visual morbidity.

RESULTS

Complete clipping rate was 90.0% without any recurrence (mean: 5.2 years). Visual morbidity was unexpectedly high at 28.9%, including 2.7% of blindness immediately after the operation, and 23.7% and 2.7% at the final examination (mean: 3.6 years). Multivariate analysis showed aneurysm size was significantly correlated with worse visual outcome. Visual morbidity was 13.3% and 11.1% for dorsal and the non-dorsal small aneurysms, respectively, and all these cases showed visual field defect limited to the nasal quadrant without decreased visual acuity. In contrast, the non-dorsal not-small aneurysms showed significantly worse visual morbidity (60%) with decreased visual acuity.

CONCLUSIONS

Clipping via extradural temporopolar approach can achieve durable treatment for small unruptured paraclinoid aneurysms with acceptable visual morbidity. Visual morbidity of the not-small non-dorsal type, however, was poor. The indications for clipping of paraclinoid aneurysm should be limited to small aneurysms, especially the dorsal type in young patients.

Simple Coiling versus Stent-Assisted Coiling of Paraclinoid Aneurysms: Radiological Outcome in a Single Center Study

Objective

Paraclinoid aneurysms are a group of aneurysms arising at the distal internal carotid artery. Due to a high incidence of small, wide-necked aneurysms in this zone, it is often challenging to achieve complete occlusion when solely using detachable coils, thus stent placement is often required. In the present study, we aimed to investigate the effect of stent placement in endovascular treatment of paraclinoid aneurysms.

Methods

Data of 98 paraclinoid aneurysms treated by endovascular approach in our center from August 2005 to June 2016 were retrospectively reviewed. They were divided into two groups: simple coiling and stent-assisted coiling. Differences in the recurrence and progressive occlusion between the two groups were mainly analyzed. The recurrence was defined as more than one grade worsening according to Raymond-Roy Classification or major recanalization that is large enough to permit retreatment in the follow-up study compared to the immediate post-operative results.

Results

Complete occlusion was achieved immediately after endovascular treatment in eight out of 37 patients (21.6%) in the stent-assisted group and 18 out of 61 (29.5%) in the simple coiling group. In the follow-up imaging studies, the recurrence rate was lower in the stent-assisted group (one out of 37, 2.7%) compared to the simple coiling group (13 out of 61, 21.3%) (p=0.011). Multivariate logistic regression model showed lower recurrence rate in the stent-assisted group than the simple coiling group (odds ratio [OR] 0.051, 95% confidence interval [CI] 0.005-0.527). Furthermore there was also a significant difference in the rate of progressive occlusion between the stent-assisted group (16 out of 29 patients, 55.2%) and the simple coiling group (10 out of 43 patients, 23.3%) (p=0.006). The stent-assisted group also exhibited a higher rate of progressive occlusion than the simple coiling group in the multivariate logistic regression model (OR 3.208, 95% CI 1.106-9.302).

Conclusion

Use of stents results in good prognosis not only by reducing the recurrence rate but also by increasing the rate of progressive occlusion in wide-necked paraclinoid aneurysms. Stent-assisted coil embolization can be an important treatment strategy for paraclinoid aneurysms when considering the superiority of long term outcome.

Vision outcomes in patients with paraclinoid aneurysms treated with clipping, coiling, or flow diversion: a systematic review and meta-analysis

OBJECTIVE

Patients with paraclinoid aneurysms commonly present with visual impairment. They have traditionally been treated with clipping or coiling, but flow diversion (FD) has recently been introduced as an alternative treatment modality. Although there is still initial aneurysm thrombosis, FD is hypothesized to reduce mass effect, which may decompress the optic nerve when treating patients with visually symptomatic paraclinoid aneurysms. The authors performed a meta-analysis to compare vision outcomes following clipping, coiling, or FD of paraclinoid aneurysms in patients who presented with visual impairment.

METHODS

A systematic literature review was performed using the PubMed and Web of Science databases. Studies published in English between 1980 and 2016 were included if they reported preoperative and postoperative visual function in at least 5 patients with visually symptomatic paraclinoid aneurysms (cavernous segment through ophthalmic segment) treated with clipping, coiling, or FD. Neuroophthalmological assessment was used when reported, but subjective patient reports or objective visual examination findings were also acceptable.

RESULTS

Thirty-nine studies that included a total of 2458 patients (520 of whom presented with visual symptoms) met the inclusion criteria, including 307 visually symptomatic cases treated with clipping (mean follow-up 26 months), 149 treated with coiling (mean follow-up 17 months), and 64 treated with FD (mean follow-up 11 months). Postoperative vision in these patients was classified as improved, unchanged, or worsened compared with preoperative vision. A pooled analysis showed preoperative visual symptoms in 38% (95% CI 28%–50%) of patients with paraclinoid aneurysms. The authors found that vision improved in 58% (95% CI 48%–68%) of patients after clipping, 49% (95% CI 38%–59%) after coiling, and 71% (95% CI 55%–84%) after FD. Vision worsened in 11% (95% CI 7%–17%) of patients after clipping, 9% (95% CI 2%–18%) after coiling, and 5% (95% CI 0%–20%) after FD. New visual deficits were found in patients with intact baseline vision at a rate of 1% (95% CI 0%–3%) for clipping, 0% (95% CI 0%–2%) for coiling, and 0% (95% CI 0%–2%) for FD.

CONCLUSIONS

To the authors’ knowledge, this is the first meta-analysis to assess vision outcomes after treatment for paraclinoid aneurysms. The authors found that 38% of patients with these aneurysms presented with visual impairment. These data also demonstrated a high rate of visual improvement after FD without a significant difference in the rate of worsened vision or iatrogenic visual impairment compared with clipping and coiling. These findings suggest that FD is an effective option for treatment of visually symptomatic paraclinoid aneurysms.

Surgical clipping is still a good choice for the treatment of paraclinoid aneurysms

Paraclinoid aneurysms are lesions located adjacent to the clinoid and ophthalmic segments of the internal carotid artery. In recent years, flow diverter stents have been introduced as a better endovascular technique for treatment of these aneurysms.

METHOD

From 2009 to 2014, a total of 43 paraclinoid aneurysms in 43 patients were surgically clipped. We retrospectively reviewed the records of these patients to analyze clinical outcomes.

RESULTS

Twenty-six aneurysms (60.5%) were ophthalmic artery aneurysms, while 17 were superior hypophyseal artery aneurysms (39.5%). The extradural approach to the clinoid process was used to clip these aneurysms. One hundred percent of aneurysms were clipped (complete exclusion in 100% on follow-up angiography). The length of follow-up ranged from 1 to 60 months (mean, 29.82 months).

CONCLUSION

Surgical clipping continues to be a good option for the treatment of paraclinoid aneurysms.

Predictors of recurrence after stent-assisted coil embolization of paraclinoid aneurysms

Stent-assisted coil embolization has been increasingly used to treat paraclinoid aneurysms. The study was aimed to evaluate safety and efficacy of stent-assisted coil embolization for paraclinoid aneurysms and explore the factors influencing the long-term outcomes. Under an institutional review board approved protocol, the clinical and angiographic data of 129 paraclinoid aneurysms in 120 patients (Male:Female=36:84; median age, 52years; range, 21-84) treated by stent-assisted coil embolization were reviewed retrospectively. Clinical status, aneurysmal morphology, treatment strategy and results were analyzed using Chi-squared tests in the univariate analysis and further analyzed using backward stepwise logistic regression. The univariate analysis indicated significance between the groups regarding hypertension, ruptured aneurysms, size, wide neck and immediate treatment results (P<0.05). Multivariate logistic regression analysis found that ruptured aneurysms (odds ratio [OR]=5.893, 95% confidence interval [CI], 1.512-23.054; p=0.011), larger size (OR=2.339; 95%CI, 1.148-4.781; p=0.020) and hypertension (OR=6.143; 95%CI, 1.560-24.183; p=0.009) might be predictors of recurrence. Stent-assisted coil embolization of paraclinoid aneurysm has a risk of recurrence. Ruptured aneurysms, larger size and hypertension may be the risk factors for recurrence.

Comparison of the effectiveness of using the optic strut and tuberculum sellae as radiological landmarks in diagnosing paraclinoid aneurysms with CT angiography

OBJECTIVE

The treatment of paraclinoid aneurysms remains challenging. It is important to determine the exact location of the paraclinoid aneurysm when considering treatment options. The authors herein evaluated the effectiveness of using the optic strut (OS) and tuberculum sellae (TS) as radiographic landmarks for distinguishing between intradural and extradural paraclinoid aneurysms on source images from CT angiography (CTA).

METHODS

Between January 2010 and September 2013, a total of 49 surgical patients with the preoperative diagnoses of paraclinoid aneurysm and 1 symptomatic cavernous-clinoid aneurysm were retrospectively identified. With the source images from CTA, the OS and the TS were used as landmarks to predict the location of the paraclinoid aneurysm and its relation to the distal dural ring (DDR). The operative findings were examined to confirm the definitive location of the paraclinoid aneurysm. Statistical analysis was performed to determine the diagnostic effectiveness of the landmarks.

RESULTS

Nineteen patients without preoperative CTA were excluded. The remaining 30 patients comprised the current study. The intraoperative findings confirmed 12 intradural, 12 transitional, and 6 extradural paraclinoid aneurysms, the diagnoses of which were significantly related to the type of aneurysm (p < 0.05) but not factors like sex, age, laterality of aneurysm, or relation of the aneurysm to the ophthalmic artery on digital subtraction angiography. To measure agreement with the correct diagnosis, the OS as a reference point was far superior to the TS (Cohen's kappa coefficients 0.462 and 0.138 for the OS and the TS, respectively). For paraclinoid aneurysms of the medial or posterior type, using the base of the OS as a reference point tended to overestimate intradural paraclinoid aneurysms. The receiver operating characteristic curve indicated that if the aneurysmal neck traverses the axial plane 2 mm above the base of the OS, the aneurysm is most likely to grow across the DDR and present as a transitional aneurysm (sensitivity 0.806; specificity 0.792).

CONCLUSIONS

High-resolution thin-cut CTA is a fast and crucial tool for diagnosing paraclinoid aneurysms. The OS serves as an effective landmark in CTA source images for distinguishing between intradural and extradural paraclinoid aneurysms. The DDR is supposed to be located 2 mm above the base of the OS in axial planes.