The Superior Cerebellar Artery Aneurysm: A Posterior Circulation Aneurysm with Favorable Microsurgical Outcomes

Staged stent-assisted, transcirculatory coiling of partially-thrombosed, mixed saccular and fusiform SCA aneurysm

SCA aneurysms are rare, making data on their management sparse compared to other posterior circulation aneurysms. While saccular aneurysms at the SCA origin can be treated with primary coiling or surgical clipping, fusiform and distal SCA aneurysms often require endovascular techniques such as stent-assisted coil embolization or parent vessel occlusion. We present a case of a mixed saccular/fusiform SCA aneurysm that underwent staged stent-assisted coil embolization. A right SCA stent was placed in the first stage. Given the acute angle between the BA and the SCA, microcatheter access and stent placement proved challenging. The decision was made to allow the stent to endothelialize and return in a staged fashion to perform a trans-radial, transcirculatory (trans-left PCoA, trans-left PCA) coil embolization. This provided a straight course between the left P1 segment and the right SCA origin, allowing easy microcatheter navigation through the stent and into the aneurysm for coil embolization.

Trapping and side-to-end superior cerebellar artery to superior cerebellar artery bypass for treatment of fusiform superior cerebellar artery aneurysm

We describe the technical nuances of in-situ bypass for treatment of a fusiform superior cerebellar artery (SCA) aneurysm via surgical trapping and a side-to-end in-situ bypass between duplicated SCAs. Our patient is a 40-year-old male who presented with an incidental aneurysm of the proximal right superior cerebellar artery (SCA). Formal angiography was performed that demonstrated a fusiform morphology of the aneurysm, as well as a duplicated SCA on that side. After extensive counseling, the patient elected to undergo surgical clip reconstruction with possible bypass. A large frontotemporal craniotomy was performed and a combined transsylvian-subtemporal approach to the ventral anterolateral brainstem was performed. After identifying the aneurysm, the tentorium was incised posterior to the insertion of the trochlear nerve to widen the operative field. An end-to-side anastomosis between the duplicated SCAs was performed, followed by trapping of the diseased arterial segment. The patient had an oculomotor nerve palsy post-operatively, however this resolved by his six-month follow-up. In-situ bypass is a viable technique for revascularizing the SCA territory during clip reconstruction of fusiform aneurysms. A duplicated SCA allows for an SCA to SCA bypass. Incising the tentorium can increase visualization of donor and recipient vessels and facilitate performance of the anastomosis.

Ruptured peripheral superior cerebellar artery dissecting aneurysms associated with primitive trigeminal artery: a case report

Background

Persistent primitive trigeminal artery (PPTA) is a remnant of the carotid-vertebrobasilar anastomoses in the embryo. Although PPTAs are discovered incidentally in most cases, altered hemodynamics may lead to increased risk of stroke. To the best of our knowledge, no reports of PPTA associated with superior cerebellar artery (SCA) dissecting aneurysms have been published in the English language.

We describe the case of a patient who presented with subarachnoid hemorrhage (SAH) due to ruptured peripheral SCA dissecting aneurysms in association with PPTA. Additionally, we discuss the relationship between PPTA and peripheral SCA aneurysms and the treatment of peripheral SCA aneurysms.

Case presentation

A 43-year-old woman presented with acute onset of headache and nausea and admitted to our hospital. She was diagnosed with SAH due to ruptured left SCA dissecting aneurysm(s) and had undergone digital subtraction angiography. The left vertebral angiography showed aneurysmal dilatations of the left S2 segment (lateral pontomesencephalic segment) along with dissection through the segments of S2 and S3 (cerebellomesencephalic segment). It also showed ipsilateral PPTA. The left vertebral artery (VA) had normal caliber and the basilar artery segment proximal to the orifice of the left PPTA was not hypoplastic. The patient underwent proximal parent artery occlusion at the S2 segment via the left VA and was successfully treated with no neurological deficits having lasted 5 months.

Conclusions

The flow alteration with PPTA may have influenced the formation of SCA dissection in this patient. Further studies are needed to understand the etiology and treatment outcomes of peripheral SCA aneurysms better.

Vascular Lesions of the Pineal Region: A Comprehensive Review of the Therapeutic Options

OBJECTIVE

Vascular lesions of the pineal region comprise aneurysms of the pineal region, arteriovenous malformations, cavernous malformations, and vein of Galen malformations. In the present report, we have offered an extensive review of each vascular pineal region lesion.

METHODS

We performed an extensive literature review, focusing on the current therapeutic options available for the different vascular lesions of the pineal region.

RESULTS

Vascular lesions of the pineal region are rare. Microneurosurgery remains a valid treatment of cavernomas, arteriovenous malformations, and aneurysms. Endovascular treatments seem to be the first option for the vein of Galen malformations, followed by microneurosurgery. Radiosurgery seems beneficial for small-size arteriovenous malformations. Complex and large vascular lesions will require a combination of multiple treatments.

CONCLUSIONS

Vascular lesions of the pineal region are complex, uncommon diseases. Thus, definitive therapeutic modalities for these lesions require further research.

Anatomic Risk Factors for S1 Segment Superior Cerebellar Artery Aneurysm Rupture: A Radiologic Study on 81 Consecutive Patients

BACKGROUND

Due to treatment associated risks, it is still debatable which unruptured aneurysm should be treated. Anatomic and morphologic characteristics may aid to predict the rupture risk of superior cerebellar artery (SCA) aneurysm and possibly support in decision- making during treatment.

OBJECTIVES

To identify morphologic characteristics that could predict the rupture of SCA aneurysms.

METHODS

A retrospective analysis of computed tomography angiography images of 81 consecutive patients harboring SCA aneurysm who were treated between 1980 to 2014 at Helsinki University Hospital was performed.

RESULTS

Of the 81 analyzed SCA aneurysms, 30 (37%) were unruptured and remaining 51 (63%) presented with subarachnoid hemorrhage. The mean ± SD size of unruptured SCA aneurysms was 6.2 ± 6.3 mm; mean size of ruptured SCA aneurysms was 5.9 ± 5.4 mm. The mean ± SD aspect ratio was 0.9 ± 0.3 in unruptured and 1.14 ± 0.44 in ruptured SCA aneurysms. The mean ± SD degree angle between basilar artery and aneurysm was 74.7 ± 24.4 in unruptured and 65.9 ± 23 ruptured SCA aneurysms. Patients with ruptured SCA aneurysm showed significantly higher aspect ratio (Mann-Whitney U, P = 0.01) and smaller aneurysm to basilar artery angle (Mann-Whitney U, P = 0.039). Aspect ratio >1.1 had 2.3 times higher risk of rupture (odds ration [OR] 2.3, 95% confidence interval [CI] 0.84-6.34). An aneurysm to basilar angle <70 degrees had 2.8 times higher risk of rupture (OR 2.75, 95% CI 1.086-6.96).

CONCLUSIONS

Ruptured SCA aneurysms are usually small in size. Higher aspect ratio and smaller angle between SCA aneurysm and basilar artery had significantly higher risk of SCA (S1 segment) aneurysm rupture.

Development of a Cadaveric Multiport Model of Posterior Circulation Aneurysm Clipping for Neurosurgery and Otolaryngology Residents

Posterior circulation aneurysms are difficult to treat with the current methods of coiling and clipping. To address limitations in training, we developed a cadaveric model to train learners on endoscopic clipping of posterior circulation aneurysms. An endoscopic transclival approach (ETA) and a transorbital precaruncular approach (TOPA) to successfully access and clip aneurysms of the posterior circulation are described. The model has flexibility in that a colored silicone compound can be injected into the cadaveric vessels for the purpose of training learners on vascular anatomy. The other option is that the model could be connected to a vascular perfusion pump allowing real-time appreciation of a pulsatile or ruptured aneurysm. This cadaveric model is the first of its kind for training of endoscopic clipping of posterior circulation aneurysms. Learners will develop proficiency in endoscopic skills, appropriate dissection, and appreciation for relative anatomy while developing an algorithm that can be employed in a real operative arena. Going forward, various clinical scenarios can be developed to enhance the realism, allow learners from different specialties to work together, and emphasize the importance of teamwork and effective communication.

Neurosurgical management of aneurysms of the vertebrobasilar system: increasing indications for endovascular therapy with a continued role for open microneurosurgery

Aneurysms of the vertebrobasilar system remain among the most challenging subsets of aneurysms to treat with an open surgical approach. Since Charles Drake's pioneering work in the 1960s, several advances in microsurgical techniques have improved outcomes and feasibility in the open surgical management of these aneurysms. In parallel, the field of endovascular neurosurgery has provided several safe and effective treatment options. Multiple trials have suggested that endovascular therapy for aneurysms of the vertebrobasilar system is superior to open surgical management in most cases. In some instances, however, open surgical management likely represents a more effective and durable option relative to endovascular therapy. Therefore, continued training of future cerebrovascular specialists in open surgery of vertebrobasilar aneurysms remains crucial. With widespread utilization of endovascular techniques, however, proper exposure of trainees to such aneurysms is growing increasingly difficult. In this review, we discuss the recent advances in the endovascular management of vertebrobasilar aneurysms while also emphasizing the continued importance of open microneurosurgery in such cases.

Posterior Circulation Aneurysms: A Critical Appraisal of a Surgical Series in Endovascular Era

The advent of the endovascular era has apparently decreased the role of microneurosurgery for many of the posterior circulation aneurysms. This study consists of a critical appraisal of a retrospective surgical series regarding posterior circulation aneurysms, targeted to define whether microneurosurgery still has a role for some of these. In 28 years, 157 aneurysms were surgically treated, 98 of which ruptured. The Average patient age was 56.7 ± 14.2 years, while in hemorrhagic cases, the mean Hunt-Hess score was 2.17 ± 0.8. Basilar tip, vertebral artery and proximal posterior inferior cerebellar artery were the most frequently involved sites. The treatment consisted of 128 clippings, 19 trappings, 7 wrappings, and 3 bypasses. A total exclusion was achieved in 88.5% of the aneurysms. An average follow-up of 67.1 ± 61.3 months proved no recurrences. The best results were observed in patients <65 years old who harbored small-to-regular aneurysms of the basilar tip, distal cerebellar arteries, or vertebral artery.Clipping proved to be a definitive and durable treatment for a large part of posterior circulation aneurysms, whereas bypass allows for treating aneurysms not amenable for coiling, stenting, or clipping. The present study confirms that microneurosurgery continues to have a paramount role within neurovascular pathology.

Superior Cerebellar Artery Aneurysms Causing Facial Pain: A Comprehensive Review

BACKGROUND

Trigeminal neuralgia caused by superior cerebellar artery aneurysms (TGN-SCAAs) is a rare event without previous analysis.

OBJECTIVE

To describe the features of TGN-SCAA based on 8 cases (7 from literature +1 illustrative case).

METHODS

All cases were thoroughly studied with gathering of their epidemiological, radiological, clinical, therapeutic, and outcome data.

RESULTS

The mean age at diagnosis was 61 yr. Gender distribution showed a female predominance (M: F = 2:6). Side distribution had a left dominance (75%). The aneurysms mean size was 15.4 mm (range: 5-27). All 5 proximal SCAAs (SCA-Basilar junction) presented a lateral-posterior projection, while all 3 distal SCAAs (s2 segment) had variable projections but constant direct trigeminal nerve (TN) contact. No hemorrhage occurred. TGN was the clinical onset in all 8 cases. The most frequent pain distribution was V1-2-3 (n = 3), followed by V1-2 (n = 1) and V1 alone (n = 1). Proximal SCAAs caused TGN through direct TN compression (n = 1), third nerve compression (n = 1), cavernous sinus compression (n = 1), or a combination thereof (n = 2). However, all distal SCAAs caused TGN by direct TN compression (n = 3). Two different treatment options were used: clipping (n = 4) and coiling (n = 4). The post-treatment Barrow Neurological Institute score for pain control was I in all cases (100%). The mRS score was 0 in 75% of cases.

CONCLUSION

TGN-SCAAs are infrequent lesions, characterized by large size, variable TGN mechanisms depending on their anatomic location, and mostly affecting the first and second trigeminal divisions. Both SCAA clipping and coiling were used equally, providing good neurological and pain relief results.

Residual Cerebral Aneurysms After Microsurgical Clipping: A New Scale, an Agreement Study, and a Systematic Review of the Literature

OBJECTIVE

The surgical repair of a cerebral aneurysm does not always lead to complete occlusion. A standardized repeatable method of reporting results of surgical clipping is desirable. Our purpose was to systematically review methods of classifying aneurysm remnants, provide a new scale with precise definitions of categories, and perform an agreement study to assess the variability in adjudicating remnants after aneurysm clipping.

METHODS

A systematic review was performed to identify ways to report angiographic results of surgical clipping between 1963 and 2017. Postclipping angiographic results of 43 patients were also independently evaluated by 10 raters of various experience and backgrounds using a new 4-category scale. Agreement between responses were analyzed using κ statistics.

RESULTS

The systematic review yielded 63 articles with 37 different nomenclatures using 2-6 categories. The reliability of judging the presence of an aneurysm remnant on catheter angiography was studied only twice, with only 2 raters each time, with contradictory results. Interobserver agreement using the new 4-category scale was moderate (κ = 0.52; 95% confidence interval, 0.43-0.62) for all observers, but improved to substantial (κ = 0.62; 95% confidence interval, 0.47-0.76) when results were dichotomized (grade 0/1 vs. 2/3).

CONCLUSIONS

Various classification schemes to evaluate angiographic results after surgical clipping exist in the literature, but they lack standardization. Adjudication using fewer, better defined categories may yield more reliable agreement.