Utility of a novel exoscope, ORBEYE, in gravity-assisted brain retraction surgery for midline lesions of the brain

Abstract

Background: Midline brain lesions, such as falx meningioma, arteriovenous malformations, and cavernous malformations, are usually approached from the ipsilateral interhemispheric fissure. To this end, patients are positioned laterally with the ipsilateral side up. However, some studies have reported the usefulness of gravity-assisted brain retraction surgery, in which patients are placed laterally with the ipsilateral side down or up, enabling surgeons to approach the lesions through the ipsilateral side or through a contralateral interhemispheric fissure, respectively. This surgery requires less brain retraction. However, when using an operative microscope, performing this surgery requires the surgeon to operate in an awkward position. A recently developed high-definition (4K-HD) 3-D exoscope system, ORBEYE, can improve the surgeon's posture while performing gravity-assisted brain retraction surgery.

Methods: We report five cases with midline brain tumors managed by resectioning with gravity-assisted brain retraction surgery using ORBEYE. We also performed an ergonomic analysis of gravity-assisted brain retraction surgery with a craniotomy model and a neuronavigation system.

Results: Gravity-assisted brain retraction surgery to the midline brain tumors was successfully performed for all five patients, using ORBEYE, without any postoperative neurological deficit.

Conclusion: Gravity-assisted brain retraction surgery to the midline brain lesions using ORBEYE is feasible, and ORBEYE is ergonomically more favorable than a microscope. ORBEYE has the potential to generalize neurosurgical approaches considered difficult due to the surgeon's awkward position, such as gravity-assisted brain retraction surgery.

Keywords: Exoscope; Gravity-assisted brain retraction surgery; Neurosurgery; Operating microscope; Tumor.

Figure 1:

Patient’s position for gravity-assisted brain retraction surgery. For the ipsilateral approach, the patients are placed in a lateral position with the tumor side facing downward at 40° vertex up. For the contralateral transfalcine approach, the patients are placed in a lateral position with the tumor side facing upward at 40° vertex up position.

Figure 2:

ORBEYE allows more natural physician positioning. (a) Image from the neuronavigation system of preoperative MRI scan from Patient 1. We set the target in the superolateral part of the tumor. Navigation pointer showing the same target with the microscope and exoscope (ORBEYE). (b) Ergonomic differences between microscope and exoscope use (ORBEYE).

Figure 3:

Preoperative and postoperative MRI scans from each patient. Patient 1 had a tumor with a maximum diameter of 26 mm with peritumoral edema present. A complete resection was made possible using a contralateral transfalcine approach. Patient 2 had a tumor with a maximum diameter of 54 mm with peritumoral edema. Partial resection was carried out using a contralateral transfalcine approach. Patient 3 had a tumor with a maximum diameter of 25 mm with peritumoral edema present. A complete resection was made possible using an ipsilateral approach. Patient 4 had a tumor with a maximum diameter of 25 mm. Partial resection was carried out using an ipsilateral approach. Patient 5 had a tumor with a maximum diameter of 30 mm. Partial resection was carried out using a contralateral approach.

Figure 4:

Intraoperative images from representative cases. Patient 1 underwent tumor resection using contralateral transfalcine approach. Falx and contralateral tumor were easily visualized by ORBEYE with high definition. Patient 4 underwent tumor resection using ipsilateral approach. Falx and tumor were easily visualized by ORBEYE with high definition. Patient 5 underwent tumor resection using contralateral approach. Falx, corpus callosum, and tumor cavity were easily visualized by ORBEYE with high definition.