5-ALA fluorescence-guided resection of pediatric low-grade glioma using the ORBEYE 3D digital exoscope: a technical report

Real-time fluorescence-guided glioblastoma resection with 5-aminolevulinic acid using ORBEYE™

BACKGROUND

Although fluorescence-guided surgery (FGS) using 5-aminolevulinic acid (5-ALA) for glioblastomas (GBMs) can maximize the extent of resection (EOR), its superiority when used with ORBEYE™, a three-dimensional exoscope, compared with that of conventional microscopy remains unclear. This study aimed to evaluate the effectiveness of ORBEYE™ in 5-ALA FGS for GBM resection and compare the results with those of conventional microscopic FGS.

METHODS

This retrospective, single-center study included 41 patients with histologically confirmed GBM who underwent 5-ALA FGS between January 2016 and April 2024. Twenty patients underwent surgery using a conventional operating microscope, while 21 underwent surgery using ORBEYE™. Tumor size, location, EOR, operative time, and surgical complications were compared between the two groups.

RESULTS

No significant differences in EOR were observed between the groups; gross total resection was achieved in 45 % and 52.4 % of patients in the microscope and ORBEYE groups, respectively. Although not significant, the ORBEYE group had shorter operative times (195.3 ± 53.8 min) than the microscope group (219.4 ± 79.3 min). Postoperative complications were comparable between the two groups. ORBEYE™ allowed continuous resection under blue light without switching modes, enabling "real-time FGS with 5-ALA," which enhanced surgical workflow, reduced surgeon's fatigue, and eliminated the need for repositioning the surgeon's eyes to the operating microscope eyepieces-although this was a subjective opinion of the surgeons.

CONCLUSIONS

ORBEYE™ provides effective real-time visualization during 5-ALA FGS for GBM resection, comparable to conventional microscopy. Its continuous fluorescence guidance and improved ergonomics may contribute to shorter operative times and reduced surgeon fatigue. ORBEYE™ is a promising tool in GBM surgery, warranting further in-depth investigation.

5-Aminolevulinic acid (5-ALA) in paediatric brain tumour surgery-a systematic review and exploration of fluorophore alternatives

PURPOSE

Paediatric brain tumours represent the most common solid malignancies in children, with extent of resection being a critical prognostic factor. Fluorescence-guided surgery using 5-aminolevulinic acid (5-ALA) is well-established for adult high-grade gliomas, but its efficacy and safety in paediatric populations remain unclear. This systematic review evaluates the utility of 5-ALA fluorescence-guided surgery in paediatric brain tumours and explores alternative fluorophores.

METHODS

A systematic review was conducted according to PRISMA guidelines, analysing studies from MEDLINE and EMBASE published up to October 2024. Data on patient demographics, tumour fluorescence patterns, surgical outcomes, and adverse effects were extracted. Statistical analyses assessed fluorescence differences across tumour types and administration parameters.

RESULTS

Twenty-three studies, including 281 paediatric patients (mean age, 10 years), were analysed. The most common tumours included pilocytic astrocytomas (n = 45), medulloblastomas (n = 45), glioblastomas (n = 35), and ependymomas (n = 27). Strong fluorescence was observed more frequently in high-grade gliomas compared to low-grade gliomas (p < 0.00001), non-glioma tumours (p < 0.00001), and high-grade non-glioma tumours (p = 0.000485). Adverse effects were mostly transient; rare complications included transaminitis and dermatologic reactions.

CONCLUSION

5-ALA fluorescence-guided surgery shows promise in the resection of high-grade gliomas in paediatric patients, improving intraoperative visualisation. However, limited fluorescence in low-grade and non-glioma tumours underscores the need for tumour-specific approaches. Emerging alternatives, such as fluorescein sodium and tozuleristide, offer potential advantages. Future research should focus on optimising 5-ALA dosing, refining timing protocols, and conducting robust prospective trials to establish efficacy and safety in paediatric populations.

Utility and Safety of 5-ALA Guided Surgery in Pediatric Brain Tumors: A Systematic Review

Background: 5-Aminolevulinic acid-guided surgery for adult gliomas has been approved by the European Medicines Agency and the US Food and Drug Administration, becoming a reliable tool for improving gross total resection rates and patient outcomes. This has led several medical centers to explore the off-label use of 5-ALA in the resection of pediatric brain tumors, assessing its efficacy and safety across various tumor types. However, given the differences between children and adults, the appropriateness of 5-ALA use in pediatric populations has not yet been fully established. Methods: We collected eligible publications from Embase, Scopus, PubMed, and Proquest, ultimately selecting 27 studies. Data extraction and retrospective analysis of 249 surgical cases were conducted to determine the current efficacy and safety of 5-ALA in pediatric brain tumors. The fluorescence rate and utility stratified by several clinical features, including WHO grade, tumor classification, and tumor location, were analyzed. Results: Most studies suggest that 5-ALA can enhance tumor identification in high-grade tumors, including glioblastomas and anaplastic astrocytomas. Changes in survival or recurrence rates associated with 5-ALA-guided resection have not been reported. None of the cases reported significant postoperative complications related to the use of 5-ALA. Conclusions: 5-ALA can aid in the resection of high-grade gliomas in pediatric patients. The efficacy of 5-ALA in low-grade gliomas and other tumors may require enhancement with additional tools or modified administration protocols. The safety of 5-ALA has reached a preliminary consensus, although further randomized controlled trials and data on survival and molecular characteristics are needed.

Exoscopic versus Microscopic Surgery in 5-ALA-Guided Resection of High-Grade Gliomas

Background: Glioma surgery has been remarkably enhanced in the past 2 decades, with improved safety and limited but improved life expectations. The fluorescence-guided resection of high-grade gliomas (HGGs) plays a central role in this sense, allowing a greater extent of resection (EOR). The introduction of exoscopic-guided surgery may be considered in implementing fluorescence techniques over traditional microscopes. We present the application and the advantages of exoscopic-guided surgery compared to microscopic surgery in tumor resection guided by 5-ALA fluorescence in patients with HGGs. Methods: Ten consecutive patients underwent surgery for HGG resection. The surgery was performed via an exoscopic-guided procedure (Olympus ORBEYE) and after the oral administration of Gliolan 5 h before the procedure. During surgery, the procedure shifted to using a microscopic (Kinevo 900, Zeiss) view. The intensity of the fluorescence under the two different procedures was subjectively measured in different picture samples during the surgery on a 1 to 5 (from minimum to maximum) scale. The brightness of the surgical field and the detailing of the anatomy were also analyzed comparatively. Results: Among the ten patients, the histopathological diagnosis was an high-grade glioma in all cases. In nine cases, it was possible to achieve gross total resection. There was no perioperative mortality. The median fluorescence intensity, on a scale of 1-5, was 4.5 in the exoscope group and 3.5 in the microscope group (p < 0.01). Conclusions: The exoscopic-guided surgery adds advantages to traditional fluorescence-guided surgery with 5-aminolevulinic acid. Beyond the important advantage of low cost and the possibility to perform collaborative surgeries, it adds a plain and continuous visualization of the tumor and offers advantages in the surgical field of fluorescence-guided glioma surgery compared to the microscopic-guided one.

From Microscopic to Exoscopic Microsurgery: Are We Facing a Change of Paradigm?

BACKGROUND

Neurosurgery is a medical branch characterized by small and deep surgical field with the need of manipulation and dissection of anatomical structures. High light and magnification are required in order to avoid injuries to important anatomical structures and to avoid permanent neurological deficits. Introduction of operative microscope made a change of paradigm in neurosurgery allowing to better see what could not be seen with common light. Nowadays, introduction of several technologies have increased the safety and efficacy of neurosurgery. Among new technologies, the 3D exoscope is emerging pretending to shift the paradigm of microneurosurgery. In this work, we aim to show our first experience with the use of the exoscope showing advantages and disadvantages.

MATERIALS AND METHODS

We reviewed our surgical database from the introduction of the exoscope in our department (in November 2020 temporarily; then from November 2021 definitively) searching for all the microsurgery interventions performed in the period.

RESULTS

From the introduction of the exoscope in our department, we operated 244 cases with the OM and 228 with the exoscope. We operated 175 lesions located in the supratentorial compartment, 29 in the infratentorial, and 24 in the spinal column. Regarding the OM, the ratios were as follows: 122 females and 122 males; 235 adults and 9 children; 66 supratentorial lesions, 14 infratentorial lesions, and 164 spine surgeries. Our team showed a progressive switch from the microscope to the exoscope. Only one member of our team preferred to continue to use the standard operative microscope.

CONCLUSIONS

Our experience showed no complications related to the use of the exoscope that proved to be safe and effective both for surgery and teaching.

Exoscopic Microsurgery: A Change of Paradigm in Brain Tumor Surgery? Comparison with Standard Operative Microscope

BACKGROUND

The exoscope is a high-definition telescope recently introduced in neurosurgery. In the past few years, several reports have described the advantages and disadvantages of such technology. No studies have compared results of surgery with standard microscope and exoscope in patients with glioblastoma multiforme (GBM).

METHODS

Our retrospective study encompassed 177 patients operated on for GBM (WHO 2021) between February 2017 and August 2022. A total of 144 patients were operated on with a microscope only and the others with a 3D4K exoscope only. All clinical and radiological data were collected. Progression-free survival (PFS) and overall survival (OS) have been estimated in the two groups and compared by the Cox model adjusting for potential confounders (e.g., sex, age, Karnofsky performance status, gross total resection, MGMT methylated promoter, and operator's experience).

RESULTS

IDH was mutated in 9 (5.2%) patients and MGMT was methylated in 76 (44.4%). Overall, 122 patients received a gross total resection, 14 patients received a subtotal resection, and 41 patients received a partial resection. During follow-up, 139 (73.5%) patients experienced tumor recurrence and 18.7% of them received a second surgery. After truncation to 12 months, the median PFS for patients operated on with the microscope was 8.82 months, while for patients operated on with the exoscope it was >12 months. Instead, the OS was comparable in the two groups. The multivariable Cox model showed that the use of microscope compared to the exoscope was associated with lower progression-free survival (hazard ratio = 3.55, 95%CI = 1.66-7.56, p = 0.001).

CONCLUSIONS

The exoscope has proven efficacy in terms of surgical resection, which was not different to that of the microscope. Furthermore, patients operated on with the exoscope had a longer PFS. A comparable OS was observed between microscope and exoscope, but further prospective studies with longer follow-up are needed.

Optimization of novel exoscopic blue light filter during fluorescence-guided resection of Glioblastoma

PURPOSE

Operative guidelines and use optimization for new surgical exoscopes are not well described in the literature. In this study, we evaluated use of the ORBEYE (Olympus) surgical exoscope system during 5-ALA fluorescence-guided resection of GBMs to optimize workflow and exoscope settings.

METHODS

The ORBEYE exoscope system was fitted with a blue light filter for 5-ALA mediated fluorescence-guided surgery (FGS). Intraoperative images were obtained during 5-ALA FGS in 9 patients with primary or recurrent GBM. The exoscope was set up at constant, increasing focal distances from the target tissue, and light source intensity varied. High-resolution 4 K images were captured and analyzed. Comparisons of fluorescence to background were then generated for use optimization.

RESULTS

Light intensity did not significantly influence tumor fluorescence (P = 0.878). However, focal distance significantly impacted relative fluorescent intensity (P = 0.007). Maximum average fluorescence was seen consistently at a focal length of 220 mm and a light intensity of approximately 75% maximum. Decreasing focal distance from 400 mm to 220 mm significantly increased visualized fluorescence (P = 0.0038).

CONCLUSIONS

The ORBEYE surgical exoscope system with blue light filter is a powerful imaging tool for 5-ALA FGS in GBM. The ORBEYE blue filter performs optimally at shorter focal distance with moderate light intensity. Similar to microscope systems, decreasing focal distance significantly influences visualized fluorescence.