Keyhole clipping of a low-lying basilar apex aneurysm without posterior clinoidectomy utilizing endoscopic indocyanine green video angiography

Abstract

Background: Basilar apex (BX) aneurysms are surgically challenging due to their anatomic location, need to traverse neurovascular structures, and proximity to multiple perforator arteries. Surgical approaches often require extensive bone resection and neurovascular manipulation. Visualization of low-lying BX aneurysms is typically obscured by the posterior clinoid and upper clivus and poses a unique challenge. Subtemporal or anterolateral approaches with a posterior clinoidectomy are often required to achieve adequate exposure, though these maneuvers can add invasiveness, risk, and morbidity to the procedure. Endoscopes and, more recently, fluoroscopic angiography capable endoscopes offer the possibility of providing improved visualization with less exposure allowing for minimally invasive clipping.

Case description: We present the case of a 42-year-old female with incidentally found 5 mm middle cerebral artery and 5 mm BX aneurysms. She underwent a minimally invasive supraorbital keyhole craniotomy for the clipping of both aneurysms. While the posterior clinoid obstructed the necessary visualization for the BX aneurysm, use of endoscopy and endoscopic fluoroscopic angiography allowed for safe and successful clipping without the need for a posterior clinoidectomy.

Conclusion: This represents the first reported case of a BX aneurysm clipping through a minimally invasive keyhole craniotomy using endoscopic indocyanine green video angiography. Use of endoscopic indocyanine green angiography, combined with keyhole endoscopic approaches, allows for safe minimally invasive clipping of challenging posterior circulation aneurysms.

Keywords: Basilar apex aneurysm; Endoscopic indocyanine green; Endoscopic surgery; Keyhole craniotomy; Minimally invasive aneurysm clipping.

Figure 1:

Three-dimensional reconstruction of a computed tomography angiogram. (a) Posterior circulation demonstrating basilar apex aneurysm (arrowhead) (b) anterior circulation demonstrating right middle cerebral artery aneurysm (arrowhead).

Figure 2:

Orbital roof-dorsum estimation line. (a) Orbital height (red line) as measured by the line extending from the anterior skull base along the sagittal scout line (yellow line) to the intersection with the horizontal orthogonal line (blue solid) from the roof of the orbit to the sagittal scout line (b) orbital height line as determined on coronal section translated onto the coronal scout line in the sagittal plane with the orbital roof-dorsum estimation line (green line) extending from the superior point to the top of the posterior clinoid process. In this patient, this line estimates that the most conservative proximal exposure from a supraorbital approach is the neck of the aneurysm.

Figure 3:

(a) Surgical exposure and treatment of the middle cerebral artery aneurysm (b) aneurysm clip placement (c) microscopic indocyanine green angiography demonstrating aneurysm occlusion and vessel patency. MCA: Middle cerebral artery, *: Aneurysm.

Figure 4:

Basilar apex aneurysm (a) microscopic exposure through oculomotor carotid window obstructed by the posterior clinoid (dashed line) (b) endoscopic exposure (c) endoscopic indocyanine green angiography (d) aneurysm clip placement (e) endoscopic view of clip construct (f) endoscopic indocyanine green angiography demonstrating complete aneurysm obliteration with maintenance of perforating arteries. BA: Basilar artery, SCA: Superior cerebellar artery, PCA: Posterior cerebral artery, Perf: Perforator artery, *: Basilar apex aneurysm.

Figure 5:

Three-dimensional reconstruction of a computed tomography angiogram demonstrating clipping of the right middle cerebral artery and basilar apex aneurysms.