Combined transsylvian-subtemporal exposure of cerebral aneurysms involving the basilar apex

Comparative Analysis of Orbitozygomatic and Subtemporal Approaches to the Basilar Apex: A Cadaveric Study

BACKGROUND

The subtemporal and orbitozygomatic approaches are the most commonly used surgical approaches for the treatment of basilar artery apex (BAX) aneurysms. Relative advantages and disadvantages are generally reported based on surgeons' experience. This study was performed to provide a detailed comparison between the subtemporal and orbitozygomatic approaches based on cadaveric dissection analysis for the treatment of BAX aneurysms.

METHODS

Subtemporal and orbitozygomatic approaches were performed on 5 cadaveric heads (10 sides), and the following variables were assessed and compared between the 2 approaches: 1) number of exposed perforators on P₁-posterior cerebral arteries (PCA); 2) lengths of exposure and clipping for bilateral PCA, superior cerebellar arteries (SCA), and basilar trunk; 3) surgical area of exposure; and 4) surgical freedom at the BAX.

RESULTS

Number of perforators exposed on P₁-PCA was not different between the subtemporal and orbitozygomatic approaches. Exposure and clipping of ipsilateral SCA and PCA were superior using the subtemporal approach, and better for contralateral SCA and PCA using the orbitozygomatic approach, all reaching statistical significance. The orbitozygomatic approach provided greater exposure and clipping length for the proximal basilar trunk. Although the surgical area of exposure was similar between the 2 approaches, the overall surgical freedom was greater in the orbitozygomatic approach.

CONCLUSIONS

The orbitozygomatic approach provides a greater number of surgical corridors to the BAX and is superior regarding multiple surgically relevant anatomic parameters. Importantly, control over the basilar trunk and over the contralateral SCA and PCA (blind spots) is superior with the orbitozygomatic approach.

Anatomical Study on the “Perforator-free Zone”: Reconsidering the Proximal Superior Cerebellar Artery and Basilar Artery Perforators

Background:

The proximal superior cerebellar artery (pSCA) is often considered a perforator-free area. Precise anatomical knowledge of this region clarifies the pathophysiology underlying posterior fossa ischemic syndromes and helps avoid treatment-related complications.

Objective:

To anatomically evaluate perforating branches arising from the pSCA and the upper basilar artery (BA).

Methods:

Forty-four SCAs from 20 cadaveric heads were examined to determine patterns of the pSCA; its morphometry for medial and lateral branches; and frequency, number, diameter, distribution, and vascular territory of perforators arising from the pSCA and rostral BA.

Results:

SCA arose as a single trunk in 36 sides (90%): mean diameter at origin was 1.38 mm; mean length was 14.± 6 7.9 mm. Ninety-nine pSCA perforator branches were present in 82% of specimens (mean, 2.3 ± 1.6; range, 0-7 perforators/side). Of these, 59% were direct, belonging to the interpeduncular group in 85% of cases; 28% were short circumflex, belonging to lateral and medial pontine group; and 13% were long circumflex, reaching the medullary perforation zone (basal cerebellar group). Median distance to the first perforator was 2.0 mm (range, 0.1–15 mm). There were 132 perforator branches in the last centimeter of the BA.

Conclusion:

The pSCA should not be regarded as a perforator-free area. Although the pSCA territories likely overlap with the posterior cerebral artery, BA, and anterior inferior cerebellar artery, the pSCA segment cannot be surgically manipulated with impunity.

Extended Lateral Transsylvian Approach for Basilar Bifurcation Aneurysms

THE SURGICAL MANAGEMENT of aneurysms of the basilar apex is one of the most challenging areas in neurosurgery. Successful treatment of this subgroup of aneurysms is dependent on the mastery of technical nuances that have been pioneered and advanced over the past 4 decades. Although both the traditional transsylvian and subtemporal approaches have distinct advantages, each is associated with significant limitations. In this article, the senior author shares his insights into a hybrid approach: the extended lateral transsylvian approach. This approach combines the assets of the two traditional approaches while eliminating their liabilities.

Surgical treatment of posterior circulation aneurysms

Distal basilar aneurysms appear to produce symptoms from hemorrhage or enlargement at least as frequently as their anterior circulation counterparts. Once giant size has been reached, the future of the patient is indeed bleak. The diagnostic evaluation and therapeutic strategy to successfully combat these lesions requires thoughtful interaction between the neurosurgeon, the neuroradiologist, and medical and critical care physicians. In my opinion, patients are best served by referral to centers equipped for these complex and dangerous procedures.