Midline suboccipital approach to a vertebral artery-posterior inferior cerebellar artery aneurysm from the rostral end of the patient using ORBEYE

Abstract

Background: The midline suboccipital approach with the patient in the prone position is safe and effective for clipping vertebral artery-posterior inferior cerebellar artery (VA-PICA) aneurysms. Using a conventional surgical microscope from the rostral end of the patient for this approach without an extreme head-down position requires the surgeon to overhang the visual axis of the microscope and perform surgical manipulations in an uncomfortable posture. We report performing the midline suboccipital approach from the rostral end with slight head-down position using ORBEYE, a new high-definition (4K) three-dimensional exoscope.

Case description: A 65-year-old woman was admitted for clipping of a right unruptured VA-PICA aneurysm (maximum diameter, 5mm) located medially and ventral to the hypoglossal canal. After induction of general anesthesia, the patient was placed in the prone position with the head titled slightly downward. A midline suboccipital approach was performed from the rostral end of the patient using ORBEYE. Clipping was safely accomplished in a comfortable posture. No operative complications occurred. Postoperative computed tomography angiography showed complete aneurysmal obstruction.

Conclusion: Exoscopic surgery using ORBEYE is feasible for a midline suboccipital approach to VA-PICA aneurysms from the rostral end of the patient with the patient in the prone with slight head-down position.

Keywords: Clipping; Exoscope; Midline suboccipital approach; ORBEYE; Posterior inferior cerebellar artery aneurysm.

Figure 1:

Preoperative imaging. (a) The patient had previously undergone clipping of a right internal carotid artery–posterior communicating artery bifurcation aneurysm. (b) Preoperative computed tomography angiography showed an unruptured right-sided vertebral artery aneurysm (maximum diameter, 5 mm) located medially and ventral to the hypoglossal canal.

Figure 2:

Intraoperative views. (a) The patient was placed in the prone position with her neck slightly flexed and head slightly bent forward, rotated 10° to the right, and fixed in a Sugita surgical head frame (Mizuho, Tokyo, Japan). (b) Overhanging the visual axis of ORBEYE, the aneurysm was visible caudal to cranial nerves (CNs) IX, X, and XI. CN XII was attached to the distal neck of the aneurysm. The AICA was found on the ventral side of the aneurysm but the structures were not in contact. (c) A 7 mm mini straight titanium Yasargil® titanium clip (Aesculap, Center Valley, PA, USA) was applied to the aneurysm neck from beneath the lower CNs using forceps with a 15° downward bend. (d) Clipping achieved complete aneurysmal obstruction. (e) Intraoperative indocyanine green angiography showed no blood flow within the aneurysm and preservation of flow in the VA and PICA.

Figure 3:

Postoperative imaging. (a) Three-dimensional computed tomography (CT) reconstruction showed the paramedian craniotomy, foramen magnum craniectomy, and resection of the right occipital bone out to the level of the condylar fossa. (b) Postoperative plain CT showed no bleeding or cerebral infarction. (c) Postoperative CT angiography showed complete obliteration of the aneurysm and preservation of the vertebral and posterior inferior cerebellar arteries.

Figure 4:

Using ORBEYE for a midline suboccipital approach performed from the rostral end of the patient, an extreme head-down position is not necessary because the operator can perform stable microsurgery even when the visual axis of ORBEYE is ventral.