A Contralateral Transcondylar Fossa Approach with Bilateral V3 Segment Exposure for Repairing Complex Vertebral Artery Aneurysms

Microsurgical partial trapping for the treatment of unclippable vertebral artery aneurysms: Experience from 27 patients and review of literature

BACKGROUND

The efficacy and safety of partial trapping for the treatment of unclippable vertebral artery aneurysms (UVAs) are still questionable. The partial trapping method (proximal or distal occlusion) was used in the treatment of aneurysms to simplify the surgical procedure and avoid postoperative complications.

METHODS

This study included 27 patients with UVAs who underwent microsurgical partial trapping between January 2015 and August 2022, and their postoperative outcomes and complications were retrospectively reviewed and evaluated.

RESULTS

Ruptured UVAs were detected in 25 (92.6%) patients, and 13 (48.1%) patients had poor-grade status. Fusiform dissection, dissecting, and fusiform aneurysms were observed in 17 (63%), 7 (25.9%), and 3 (11.1%) patients, respectively. By location, preposterior inferior cerebellar artery (PICA), PICA, post- PICA, and non-PICA types were noted in 7 (25.9%), 9 (33.3%), 6 (22.2%), and 5 (18.5%) patients, respectively. Microsurgical partial trapping was performed in all patients (blind-alley formation in 96.3%). Complete aneurysm obliteration was achieved in 26 (96.3%) patients. Immediate complete obliteration was achieved in 21 (77.8%) patients, delayed thrombosis within 7 days in 5 (18.5%), and nearly complete obliteration in 1 (3.7%). No re-bleeding was detected in all patients. Favorable outcomes 3 months after the operation were achieved by 92.9% of the patients in the good-grade group and 85.2% overall.

CONCLUSIONS

Microsurgical partial trapping, especially the blind-alley formation technique, was a safe and effective treatment of UVAs with high rates of aneurysm thrombosis. The appropriate sites for clip occlusion were dependent on the angioarchitecture of UVAs.

Course of the V3 segment of the vertebral artery relative to the suboccipital triangle as an anatomical marker for a safe far lateral approach: A retrospective clinical study

Background:

The third segment of the vertebral artery (V3) is vulnerable during far lateral and retrosigmoid approaches. Although the suboccipital triangle (SOT) is a useful anatomical landmark, the relationship between V3 and the muscles forming the triangle is not well-described. We aimed to demonstrate the relationship between the V3, surrounding muscles, and SOT in clinical cases.

Methods:

Operative videos of patients with the vertebral artery (VA) and posterior inferior cerebellar artery (PICA) aneurysms treated with occipital artery-PICA bypass through the far lateral approach were examined. Videos from January 2015 to October 2021 were retrospectively reviewed to determine anatomy of the V3 and the SOT.

Results:

Fourteen patients were included in this study. The ipsilateral V3 was identified without injury in all patients using the bipolar cutting technique. The lateral 68.2% of the horizontal V3 segment, including the V3 bulge, was covered by the inferomedial part of the superior oblique muscle (SO). The medial 23.9% was covered by the inferolateral part of the rectus capitis posterior major muscle. The inferomedial part of the horizontal V3 segment is located within the SOT.

Conclusion:

Most of the V3, including the V3 bulge, were located beneath the SO and the inferomedial part of V3 located within the SOT. Elevation of the SO should be performed carefully using the bipolar cutting technique to avoid injury to the V3. To the best of our knowledge, this is the first description of the V3 relative to the SOT in the clinical setting.

The assessment of the frequency and arrangement of the subsegmental branches of V3 using computed tomography angiography

Background

The frequency and arrangement of the subsegmental branches of the third portion of the vertebral artery (V3) have been assessed in small samples by autopsy, but they have not been assessed by computed tomography angiography (CTA). To determine the frequency and arrangement of subsegmental branches of V3 by CTA and to analyze the interrelationships among frequency, arrangement, sex, and side-to-side.

Methods

First, the radiology records of 668 consecutive patients who underwent cervical or craniocervical CTA scans from October 1, 2017 to October 31, 2019 were retrospectively retrieved. Second, the four demarcation points were ascertained to define the three subsegments by reviewing the resource images, namely, the vertical portion of V3(V3v), horizontal portion of V3(V3h), and extradural portion of V3(V3e). Then, the numerical value and the location of the bifurcating branch in each subsegment of V3 were recorded. Third, the frequency and arrangement of the branches was assessed, and the relationships between sex, laterality and frequency and arrangement were analyzed as well as the interobserver performance.

Results

On the left, 25%, 20.21%, and 6.59% were the frequencies of one branch in the V3v, V3h, and V3e, and 1.05%, 0.00%, and 0.45% were the frequencies of two branches, respectively. On the right, 25.04%, 17.07%, and 6.44% were the frequencies of one branch in the V3v, V3h, and V3e, and 1.04%, 0.3%, and 0.15% were the frequencies of two branches, respectively. There were no differences between the side-to-side and numerical values of the branches according to the t-test (P=0.4341, P=0.7968), and there were no differences between the side-to-side variable, sex variable and number of branches according to the t-test (P=0.4474, P=0.3593). There were no differences between the side-to-side and eight arrangements (permutation of 000; 100; 110; 111; 010; 011; 001; 101) by using the two-sample KS test (P=0.942), and there were no differences between sex and the eight arrangements according to the two-sample KS test (P=0.9973, P=0.8519). The interobserver reliability was excellent (Spearman's ranked correlation: 0.9927).

Conclusions

The frequency and arrangement of V3 subsegmental branches could be displayed by source imaging with CTA, and there were no significant differences according to the sex or side of the individual. It was imperative to acquaint the subsegmental branches before the operation involving V3 in the craniocervical junction to determine the surgical approach and reduce bleeding during the surgical procedures.

Surgical microanatomy of the occipital artery for suboccipital muscle dissection and intracranial artery reconstruction

Background:

The occipital artery (OA) is an important donor artery for posterior fossa revascularization. Harvesting the OA is difficult in comparison to the superficial temporal artery because the OA runs between suboccipital muscles. Anatomical knowledge of the suboccipital muscles and OA is essential for harvesting the OA during elevation of the splenius capitis muscle (SPL) for reconstruction of the posterior inferior cerebellar artery. We analyzed the running pattern of the OA and its anatomic variations using preoperative and intraoperative findings.

Methods:

From April 2012 to March 2018, we surgically treated 162 patients with suboccipital muscle dissection by OA dissection using the lateral suboccipital approach. The running pattern and relationship between the suboccipital muscles and OA were retrospectively analyzed using the operation video and preoperative enhanced computed tomography (CT) images. The anatomic variation in the running pattern of the OA was classified into two types: lateral type, running lateral to the muscle and medial type, running medial to the longissimus capitis muscle (LNG).

Results:

The medial pattern was observed in 107 (66%) patients and the lateral pattern in 54 (33.3%); 1 (0.6%) patient had the OA running between the LNGs.

Conclusion:

Preoperative CT is effective in determining the running course of the OA, which is important for safely harvesting the OA during SPL elevation. There is a risk of causing OA injury in patients with the lateral pattern. This is the first report showing that the OA rarely runs in between the LNGs.

Contralateral Transcondylar Fossa Approach with Bilateral V3 Segment Exposure for Clipping of Vertebral Artery Aneurysm Which Deviates Across Midline: A Case Report and Review Article

This article reports a patient with unruptured right vertebral artery aneurysm which deviates across the midline to the left side. The contralateral (left) transcondylar fossa approach with bilateral V3 exposure is used for aneurysm clipping. The literature related to this technique is also reviewed.

Multistage "Hybrid" (Open and Endovascular) Surgical Treatment of Vertebral Artery-Thrombosed Giant Aneurysm by Trapping and Thrombectomy

BACKGROUND

Surgical treatment of vertebral artery (VA)-thrombosed giant aneurysms requires achieving both obliteration of the parent artery to prevent bleeding and dome thrombectomy to relieve the brain stem from mass effect. To secure both proximal and distal control of complex VA aneurysms, the contralateral approach to the aneurysm might be a useful alternative, as previously described. We successfully treated a case of VA-thrombosed giant aneurysm in a new, original way by combining craniotomy (ipsilateral and contralateral) and the endovascular technique.

CASE DESCRIPTION

A 48-year-old man presented with a thrombosed giant aneurysm of the right VA compressing the brain stem. Treatment consisted of endovascular proximal ligation of the VA followed by 2-staged craniotomy for complete trapping of the aneurysm and intra-aneurysmal thrombectomy. The VA distal to the aneurysm was obliterated via contralateral craniotomy as only that provided adequate working space. Finally, intra-aneurysmal partial thrombectomy was performed through an ipsilateral craniotomy, which also made possible the obliteration of the eventually dangerous remaining vasa vasorum and additional proximal ligation of the VA.

CONCLUSIONS

Based on pathologic and surgical anatomical characteristics, a combination of an endovascular procedure with 2-staged craniotomy for complete trapping, thrombectomy, and vasa vasorum obliteration could be considered a feasible way to treat VA-thrombosed giant aneurysms located ventral to the brain stem and have their distal neck portions/patent vessel beyond the midline toward the contralateral side.