Multicenter Investigation of Channel-Based Subcortical Trans-Sulcal Exoscopic Resection of Metastatic Brain Tumors: A Retrospective Case Series

Exoscope aided trans-sulcal minimally invasive parafascicular resection of a paediatric brainstem pilocytic astrocytoma using a tubular retractor system

The surgical management of brainstem glioma is challenging and has significant morbidity. Advances in surgical armamentarium has presented the opportunity to tackle these lesions. We present the case of a paediatric patient with a 2.3cm midbrain pilocytic astrocytoma. With the aid of tractography, neuro-navigation, 3-dimensional exoscope and a tubular retractor, near total resection of the tumour was achieved through a trans-sulcal para-fascicular approach without permanent injury to the corticospinal tract. To our knowledge this is the first report of a brainstem tumour resected using this approach and demonstrates what can be achieved with synergistic utility of evolving technologies in neurosurgery.

Intraoperative Imaging and Optical Visualization Techniques for Brain Tumor Resection: A Narrative Review

Advancements in intraoperative visualization and imaging techniques are increasingly central to the success and safety of brain tumor surgery, leading to transformative improvements in patient outcomes. This comprehensive review intricately describes the evolution of conventional and emerging technologies for intraoperative imaging, encompassing the surgical microscope, exoscope, Raman spectroscopy, confocal microscopy, fluorescence-guided surgery, intraoperative ultrasound, magnetic resonance imaging, and computed tomography. We detail how each of these imaging modalities contributes uniquely to the precision, safety, and efficacy of neurosurgical procedures. Despite their substantial benefits, these technologies share common challenges, including difficulties in image interpretation and steep learning curves. Looking forward, innovations in this field are poised to incorporate artificial intelligence, integrated multimodal imaging approaches, and augmented and virtual reality technologies. This rapidly evolving landscape represents fertile ground for future research and technological development, aiming to further elevate surgical precision, safety, and, most critically, patient outcomes in the management of brain tumors.

Use of tubular retractors to access deep brain lesions: A case series

BACKGROUND

Deep-seated intracranial lesions can be accessed using blade retractors that may disrupt white matter tracts, exert pressure on adjacent tissue, and lead to post-operative venous injury. Tubular retractors may minimize disruption to white matter tracts by radially dispersing pressure onto surrounding tissue. This study characterizes perioperative outcomes in patients undergoing biopsy or resection of intracranial pathologies using tubular retractors.

METHODS

Adult patients (≥18 years) undergoing neurosurgical intervention using tubular retractors at a single health system (January 2016-February 2022) were identified through chart review. Demographics, disease characteristics, management data, and clinical outcomes were collected.

RESULTS

A total of 49 patients were included; 23 (47%) had primary brain tumors, 8 (16%) metastases, 6 (12%) intracranial hemorrhage (ICH), 5 (10%) cavernomas, and 7 (14%) other pathologies. Lesions were located subcortically (n = 19, 39%), intraventricularly (n = 15, 31%), and in deep gray matter (n = 11, 22%). Gross total resection (GTR) or near GTR was achieved in 21 of 26 (80.8%) patients with intracranial lesions where GTR was the goal of surgery; 10 of 11 (90.9%) biopsies in patients with masses were diagnostic. Five of six (83.3%) ICHs were totally or near totally evacuated. Seventeen patients (35%) had major complications post-operatively. The most common complications were DVT/PE (n = 7, 14%) and seizures (n = 6, 12%). For patients who experienced post-operative seizures, 3 had seizures preoperatively and 1 had seizures in the context of electrolyte derangements. No patients died of post-operative complications.

CONCLUSION

This operative approach may facilitate safe and efficacious biopsy or resection of deep-seated intracranial pathologies.

3D Exoscopes in Experimental Microanastomosis: A Comparison of Different Systems

Background: In recent years, three-dimensional exoscopes have been increasingly applied in neurosurgery. Multiple exoscopic systems are available, all offering specific features. In this study, we assessed practical and visualization performance of four different exoscopic systems in a highly challenging microsurgical procedure, and evaluated whether these affected the quality of work. Methods: We included four different exoscopes: Olympus ORBEYE, Zeiss KINEVO, Storz VITOM, and Aesculap AEOS. With each exoscope, ten experimental bypass procedures were carried out on chicken wing vessels at a depth of 3 cm. We evaluated the quality of the anastomoses, the practical considerations for the setup of the exoscopic systems, and the visualization quality by tracking the number of unnecessary movements. Results: All included exoscopes enabled us to perform the bypass procedures with mostly adequate or excellent results. Surgically, the most pronounced difference between the exoscopes was the duration of the procedure, which was mainly due to the number of unnecessary movements. Practically, the exoscopes differ highly which is important when considering which exoscope to apply. Conclusions: This is the first study comparing different exoscope systems while performing the same challenging microsurgical procedure. We found major practical differences between the exoscopes that determine the suitability of an exoscope based on the demands and conditions of the surgical procedure. Therefore, preprocedural practical training with the exoscope is required.

Combined Transoral Exoscope and OARM-Assisted Approach for Craniovertebral Junction Surgery. New Trends in an Old-Fashioned Approach

BACKGROUND

The introduction of recent innovations in the field of intraoperative imaging and neuronavigation, such as the O-arm StealthStation, allows for obtaining crucial intraoperative data by performing safer and controlled surgical procedures. As part of the improvement of surgical visual magnification and wide expansion of surgical corridors, the 3D 4 K exoscope (EX) has nowadays become an interesting and useful tool. The transoral approach (TOA) is the historical gold-standard direct microsurgical route to ventral craniovertebral junction (CVJ).

METHODS

We herein report our experience, consisting of ten cases via TOA concerning the simultaneous application of an O-arm with a StealthStation navigation system (Medtronic, Memphis, TN) and an imaging system, along with the 3D 4 K exoscopes in the TOA, for the treatment of CVJ pathologies.

RESULTS

No intraoperative neurophysiological changes or postoperative infections occurred, but neurological improvement was evident in all the patients. A complete decompression and a stable instrumentation and fusion of the CVJ were accomplished in all cases at the maximum follow-up time.

CONCLUSIONS

With EX, the role of the surgeon becomes self-sufficient with better individual surgical freedom compared to endoscopic surgery and excellent 3D vision and magnification. O-arms offer absolutely reliable intraoperative support for more-effective CVJ decompression. Nevertheless, with O-arm-assisted neuronavigation, it can be difficult to navigate C1 lateral masses and C2 isthmi, and converting 3D into 2D real-time navigation can be quite complicated. Finally, the combination of an EX with an O-arm appears more time-consuming compared to the old-fashion one.

Three-dimensional High-definition Exoscope in Minimally Invasive Transforaminal Lumbar Interbody Fusion: A Retrospective Cohort Study

OBJECTIVES

The operative microscope (OM) has revolutionized the field of modern spine surgery, however, it remains limited by several drawbacks. Recently, the exoscope (EX) system has been designed to assistant spine surgery. It provides a three-dimensional (3D) high-definition (HD) operative experience and becomes an alternative to the OM. The aim of the study was to evaluate the clinical outcomes, advantages and limitations of EX-assisted minimally invasive transforaminal lumbar interbody fusion (EMIS-TLIF) and OM-assisted MIS-TLIF (OMIS-TLIF).

METHODS

The clinical outcomes were assessed in 47 patients with lumbar degenerative diseases (LDD) who underwent MIS-TLIF assisted with the OM or EX between January 2019 and September 2020. A total of 22 were treated with EMIS-TLIF, and 25 received OMIS-TLIF. Perioperative parameters (including sex, age, number of fusion levels and body mass index), perioperative parameters (operation time, intraoperative blood loss, postoperative drainage, postoperative hospitalization stay, and duration of follow-up), visual analogue scale (VAS) of back pain, VAS of leg pain, Oswestry disability index (ODI) scores and clinical outcomes were assessed and compared. Image quality, handling of equipment, ergonomics, 3D glasses and educational usefulness were scored according to a questionnaire.

RESULTS

Operation time in the OMIS-TLIF group (121.92 ± 16.92 min) was significantly increased compared with that in the EMIS-TLIF group (111.00 ± 19.87 min) (P < 0.05). The VAS of the back pain and ODI scores in the EMIS-TLIF group were significantly lower compared with the OMIS-TLIF group at 1 week postoperatively (P < 0.05). The good-excellent outcomes rate was 90.91% in the EMIS-TLIF group and 88.00% in the OMIS-TLIF group, and there was no significant difference. A total of 44 visits completed the questionnaire. The results of the questionnaire showed that the EX has exhibited advantages regarding handing of equipment, ergonomics and educational usefulness, and comparable image quality as compared with the OM, however, operating surgeons complained uncomfortable sensation when wearing 3D glasses.

CONCLUSIONS

The EMIS-TLIF was a safe and effective procedure in the management of LDD as compared with the OMIS-LIF. Meanwhile, EMIS-TLIF might resulted in a short operation time.

High-definition two-dimension video telescope operating monitor-assisted brain and spinal surgery in pediatrics: is it an acceptable substitute for microscopic surgery?

PURPOSE

Vision and ergonomics are crucial variables for successful outcomes during neurosurgery procedures. Two-dimension video telescope operating monitor (VITOM) exoscope has emerged as an alternative, which is cheaper than microscope. The aim of this study is to evaluate the clinical utility of 2D VITOM and to compare its merits and demerits with respect to microscope.

METHODS

VITOM 2D (Karl Storz, Germany) was used in 9 cranial and 5 spinal pediatric cases. While KINEVO operative microscope (Carl Zeiss, Germany) was used in 12 cranial and 6 spinal pediatric patients. All surgeries were performed by single senior neurosurgeon. The author's experience and opinions, as well as qualitative data, were analyzed. A comparison was made on image quality, illumination, field of view, and magnification of the operative field and ergonomics.

RESULTS

Seven out of 9 cranial pediatric cases were switched from VITOM 2D to operative microscope due to low-image definition in depth of cranial cavity. Poor visualization of bleeding source in surgical field was another major drawback. Two cranial cases in which exoscope were used exclusively, included superficial tumors. In all 5 spinal cases, VITOM 2D was successfully used without any major difficulty. The exoscope's advantages were observed in ergonomics and ease in switching to naked eyes, but the microscope's field of view, illumination, magnification, and user-friendliness was considered superior.

CONCLUSION

2D-VITOM is best suited for spinal and superficial cranial tumors. However, a lot of modifications are to be done especially in optics to become a substitute for operative microscope.

Wide Dissection Trans-Sulcal Approach for Resection of Deep Intra-Axial Lesions in Eloquent Brain Areas

Introduction: Resection of intra-axial tumors (IaT) in eloquent brain regions risks major postoperative neurological deficits. Awake craniotomy is often used to navigate these areas; however, some patients are ineligible for awake procedures. The trans-sulcal approach (TScal) was introduced to reduce parenchymal trauma during tumor resection. We report our experiences utilizing TScal for resection of deep IaT located in eloquent areas. Materials and Methods: This is a single-center retrospective analysis of patients who underwent IaT resection in eloquent areas via TScal from January 2013 to April 2021. Seventeen cases were reviewed, and relevant data was collected. Fluorescence-guided surgery with 5-aminolevulinic acid (ALA) and intraoperative ultrasound was performed in some cases. Results: Seventeen patients (10 males, 7 females) averaging 61.2 years-old (range, 21-76) were included in this study. Average length of stay was 4.8 days, and only 2 patients (11.8%) required hospital readmission within 30 days. Gross total resection (GTR) was achieved in 15 patients (88.2%), while subtotal resection occurred in 2 patients (11.8%). Eleven patients (64.7%) reported full resolution of symptoms, 4 patients (23.5%) reported deficit improvement, and 2 patients (11.8%) experienced no change from their preoperative deficits. No patient developed new permanent deficits postoperatively. Discussion: GTR, preoperative deficit reduction, and complications were comparable to awake craniotomy and other TScal studies. Ancillary intraoperative techniques, such as brain mapping, 5-ALA and intraoperative ultrasound, are afforded by TScal to improve resection rates and overall outcomes. Conclusions: TScal can be an option for patients with deep lesions in eloquent areas who are not candidates for awake surgeries.

The Exoscope in Neurosurgery: An Overview of the Current Literature of Intraoperative Use in Brain and Spine Surgery

Background: Exoscopes are a safe and effective alternative or adjunct to the existing binocular surgical microscope for brain tumor, skull base surgery, aneurysm clipping and both cervical and lumbar complex spine surgery that probably will open a new era in the field of new tools and techniques in neurosurgery. Methods: A Pubmed and Ovid EMBASE search was performed to identify papers that include surgical experiences with the exoscope in neurosurgery. PRISMA guidelines (Preferred Reporting Items for Systematic Reviews and Meta-analyses) were followed. Results: A total of 86 articles and 1711 cases were included and analyzed in this review. Among 86 papers included in this review 74 (86%) were published in the last 5 years. Out of 1711 surgical procedures, 1534 (89.6%) were performed in the operative room, whereas 177 (10.9%) were performed in the laboratory on cadavers. In more detail, 1251 (72.7%) were reported as brain surgeries, whereas 274 (16%) and 9 (0.5%) were reported as spine and peripheral nerve surgeries, respectively. Considering only the clinical series (40 studies and 1328 patients), the overall surgical complication rate was 2.6% during the use of the exoscope. These patients experienced complication profiles similar to those that underwent the same treatments with the OM. The overall switch incidence rate from exoscope to OM during surgery was 5.8%. Conclusions: The exoscope seems to be a safe alternative compared to an operative microscope for the most common brain and spinal procedures, with several advantages that have been reached, such as an easier simplicity of use and a better 3D vision and magnification of the surgical field. Moreover, it offers the opportunity of better interaction with other members of the surgical staff. All these points set the first step for subsequent and short-term changes in the field of neurosurgery and offer new educational possibilities for young neurosurgery and medical students.

Robotic-Assisted Digital Exoscope for Resection of Cerebral Metastases: A Case Series

BACKGROUND

Surgical resection is the primary treatment for cerebral metastases with safe complete resection as the goal. The robotically assisted digital surgical exoscope is a novel system with advanced visualization methods with recent applications in neurosurgery.

OBJECTIVE

To evaluate the outcomes for patients with cerebral metastases undergoing resection with the surgical exoscope.

METHODS

Data were retrospectively collected from patients with cerebral metastases where resection was achieved with using the surgical exoscope from 2016 to 2020. Demographics, clinical, imaging, and operative and outcome findings were collected. The relationship between perioperative data and discharge disposition as well as progression-free survival (PFS) and 12 mo overall survival (OS) was assessed.

RESULTS

A total of 31 patients (19 males) with a median patient age 63 yr (range 38-80) were included. Average pre- and postoperative volumes were 18.1 cc and 0.75 cc, respectively. Mean depth of the resected lesions was 0.6 cm (range 0-3.6 cm). Complete resection was achieved in 64.5% of patients. The mean extent of resection was 96.7%, with 71.0% achieving PFS at 6 mo. Overall PFS rate was 58.1% and the OS rate at 12 mo was 83.9%. Neurological complications included motor (35.5%) and sensory (12.9%) deficits, with 12 patients reporting no postoperative symptoms.

CONCLUSION

The surgical exoscope can delineate tumor tissues with high resolution, as shown by a gross total resection achieved for the majority of cases in our series. Postoperative complications and patient outcomes were similar to those reported with use of the operative microscope. Use of the exoscope can provide optimal visualization and delineation of cerebral metastases.

Surgical advances in the management of brain metastases

As the epidemiological and clinical burden of brain metastases continues to grow, advances in neurosurgical care are imperative. From standard magnetic resonance imaging (MRI) sequences to functional neuroimaging, preoperative workups for metastatic disease allow high-resolution detection of lesions and at-risk structures, facilitating safe and effective surgical planning. Minimally invasive neurosurgical approaches, including keyhole craniotomies and tubular retractors, optimize the preservation of normal parenchyma without compromising extent of resection. Supramarginal surgery has pushed the boundaries of achieving complete removal of metastases without recurrence, especially in eloquent regions when paired with intraoperative neuromonitoring. Brachytherapy has highlighted the potential of locally delivering therapeutic agents to the resection cavity with high rates of local control. Neuronavigation has become a cornerstone of operative workflow, while intraoperative ultrasound (iUS) and intraoperative brain mapping generate real-time renderings of the brain unaffected by brain shift. Endoscopes, exoscopes, and fluorescent-guided surgery enable increasingly high-definition visualizations of metastatic lesions that were previously difficult to achieve. Pushed forward by these multidisciplinary innovations, neurosurgery has never been a safer, more effective treatment for patients with brain metastases.

The Utility of High-Definition 2-Dimensional Stereotactic Exoscope in Cranial and Spinal Procedures

BACKGROUND

The use of an exoscope in neurosurgical procedures has been proposed to improve ergonomics and to overcome the limitations faced with the microscope and endoscope. However, there remains scarcity of data regarding its surgical utility and outcomes.

OBJECTIVES

The authors report their experience and evaluate the surgical outcomes using a high-definition 2-dimensional (HD-2D) stereotactic exoscope in the management of various cranial and spinal pathologies.

METHODS

We retrospectively identified patients who underwent neurosurgical procedures using the HD-2D stereotactic exoscope over a 2-year period. Demographic and surgical characteristics were analyzed.

RESULTS

Twenty-nine patients (70.7%) underwent cranial surgery, and 12 patients (29.3%) underwent spine surgery. In patients having brain tumor removal, gross total resection was achieved in 18 patients (62.1%); with an overall average pathology size of 4.2±1.6 cm. Adjuvant utilization of the microscope was required in 4 cranial cases (13.8%) to ensure optimal resection rate. Three complications and 2 mortalities were encountered in the cranial group during a mean follow-up of 4.6±3.3 months. In the spinal cohort, the HD-2D stereotactic exoscope was utilized for anterior decompression and fusion (n=5), posterior decompression and fusion (n=5), and microdiscectomy and foraminotomy (n=2). No complications were encountered in the spinal group during a mean follow-up of 3.8±2.7 months.

CONCLUSION

The HD-2D stereotactic exoscope offers a wider field of view, greater mean focal distance, enhanced ergonomics, and immersive stereotactic visual experience. The lack of stereopsis remains the principal limitation of its use, and further optimization of surgical outcomes might be achieved with newer 3D models.

Four Hands Surgery for Intracerebral Hemorrhage using Orbeye: Educational Values and Ergonomic Advantages - A Technical Note

We have developed a new educational approach to microsurgery in which a trainee and supervisor can cooperate with “4 hands” using the exoscope. We evaluated 4-hands surgery for intracranial hemorrhage (ICH) using the exoscope to validate the educational value and ergonomic advantages of this method. Thirty consecutive patients who underwent surgery for ICH using the exoscope between December 2018 and May 2020 were studied retrospectively. All operations were performed by a team comprising a supervisor (assistant) and a trainee (main operator). The assistant set the visual axis of the exoscope, and adjusted focus and magnification as a scopist. After setting the ORBEYE, the supervisor helped retract the brain and withdraw and irrigate the hematoma using suction tubes or brain retractors. Moreover, the trainee evacuated the hematoma with a suction tube and coagulated using bipolar forceps. Patient background and results of treatment were evaluated. Intraoperative postures of the operators were observed, and schemas compared with the use of a conventional microscope were developed. All microsurgical procedures were accomplished by a trainee with a supervisor using only the exoscope. During the surgery, the surgeons could work in a comfortable posture, and the supervisor and trainee could cooperate in microsurgical procedures using their four hands. The results of the present case series concerning evacuation of ICH were not inferior to those described in previous reports. To increase opportunities for education in microsurgery, 4-hands surgery for ICH using the exoscope appears feasible and safe and offered excellent educational value and ergonomic advantages.

Beyond magnification and illumination: preliminary clinical experience with the 4K 3D ORBEYE™ exoscope and a literature review

BACKGROUND

The operating microscope (OM) is an invaluable tool in neurosurgery but is not without its flaws. The ORBEYE™ (Olympus, Tokyo, Japan) is a 4K 3D exoscope aspiring to offer similar visual fidelity but with superior ergonomics. 2D visualisation was a major limitation of previous models which newer 3D exoscopes attempt to overcome. Here, we present our initial experience using a 4K 3D exoscope for neurosurgical procedures.

OBJECTIVE

To evaluate the feasibility of the ORBEYE™ exoscope in performing neurosurgery and review of the literature.

METHODS

All patients undergoing neurosurgery performed by a single surgeon, using the ORBEYE™, were assessed. Descriptive statistics and data relating to complications and operative time were recorded and analysed. An anecdotal literature review was performed for the experience of other authors using 4K 3D exoscopes in neurosurgery and compared to our subjective experience with the ORBEYE™.

RESULTS

18 patients underwent surgery using the ORBEYE™. There were no 30-day post-operative complications observed. Our experience and that of other authors suggests that the ORBEYE™ offers comparable visualisation to the traditional OM, with superior ergonomics and an enhanced experience for assistants and observers.

CONCLUSION

Neurosurgery can be performed safely and effectively with the ORBEYE™, with improved ergonomics and educational benefit. There appears to be a short learning curve provided one has experience with endoscopic surgery and the use of a foot pedal.

Cost-effectiveness of stereotactic laser ablation (SLA) for brain tumors

BACKGROUND

Stereotactic laser ablation(SLA) or laser interstitial thermal therapy (LITT) has been increasingly adopted as a treatment for primary and metastatic brain cancers. Here, we examined the published economic assessments of SLA, and review the current state of knowledge.

METHODS

The PubMed database was queried for articles investigating the cost-effectiveness of LITT. 3068 articles were screened. Two studies that met the inclusion criteria were included in this review.

RESULTS

Cost-effectiveness analysis(CEA) favored SLA(n = 8) relative to craniotomy (n = 92) for brain metastases (Mean difference [MD]=-US$6522; 95% confidence interval (CI) -$11,911 to -$1133; p = 0.02). SLA (n = 19) was found to be cost equivalent to craniotomy (n = 248) (MD=-US$1669; 95%(CI) -$8192 to $4854, p = 0.62) for primary brain tumors in general. CEA favored SLA for a subset of primary brain cancers. SLA was found to be cost-effective for difficult to access high-grade gliomas(HGG). When compared to 'other' existing treatments, the cost per life-years gained (LYG) through SLA was ∼$29,340, a threshold below that set for new technology adaptation in the U.S. Factors contributing to these cost-effectiveness were: (1) SLA of HGGs was associated with three-months prolongation in survival; (2) SLA of brain metastasis was associated with (i) shorter average length of stay (SLA: 2.3 days; craniotomy: 4.7 days), (ii) decreased discharge to inpatient rehabilitation facility (IRF), skilled nursing facility (SNF), or home healthcare (SLA: 14.8%; craniotomy: 52%), (iii) lowered 30-day readmission (SLA: 0%; craniotomy: 14.1%).

CONCLUSION

There is limited data on the cost-effectiveness of SLA. In the available literature, SLA compared favorably to craniotomy in terms of cost-effectiveness as a treatment for primary and metastatic brain cancers.

Impact of different visualization devices on accuracy, efficiency, and dexterity in neurosurgery: a laboratory investigation

OBJECTIVE

Extracorporeal telescopes (exoscopes) have been the latest addition to the neurosurgeons' armamentarium, acting as a bridge between operating microscopes and endoscopes. However, to the authors' knowledge there are no published preclinical laboratory studies of the accuracy, efficiency, and dexterity of neurosurgical training for the use of 2D or 3D exoscopes compared with microscopes.

METHODS

In a controlled experimental setup, 22 participating neurosurgery residents performed simple (2D) and complex (3D) motor tasks with three visualization tools in alternating sequence: a 2D exoscope, 3D exoscope, and microscope, using a block randomization model based on the neurosurgeons' prior training experience (novice, intermediate, and senior: n = 6, 12, and 4, respectively). Performance scores (PS; including error and efficiency scores) and dexterity scores (DS) were calculated to objectify the accuracy, efficiency, and finesse of task performance. Repeated measures ANOVA analysis was used to compare the PS, DS, and cumulative scores (CS) of candidates using the three visualization aids. Bland-Altman plots and intraclass correlation coefficients were generated to quantify intraobserver and interobserver agreement for DS. Subgroup analysis was performed to assess the impact of participants' prior training. A postexercise survey was conducted to assess the comfort level (on a 10-point analog scale) of the participants while using each visualization tool for performing the suturing task.

RESULTS

PS, DS, and CS were significantly impacted by the visualization tool utilized for 2D motor tasks (p < 0.001 for each), with the microscope faring better than the 2D exoscope (p = 0.04) or 3D exoscope (p = 0.008). The PS for the 3D object transfer task was significantly influenced by the visualization aid used (p = 0.007), with the microscope and 3D exoscope faring better than the 2D exoscope (p = 0.04 for both). The visualization instrument used significantly affected the DS and CS for the suturing task (p < 0.001 for both), with the microscope again scoring better than the 2D exoscope (p < 0.001) or 3D exoscope (p = 0.005). The impact of the visualization aid was more apparent in participants with a shorter duration of residency (novice, p = 0.03; intermediate, p = 0.0004). Participants also felt the greatest operational comfort while working with a microscope, 3D exoscope, and 2D exoscope, in that order (p < 0.0001).

CONCLUSIONS

Compared with 3D and 2D exoscopes, an operating microscope provides better dexterity and performance and a greater operational comfort level for neurosurgeons while they are performing 2D or 3D motor tasks. For performing complex 3D motor tasks, 3D exoscopes offer selective advantages in dexterity, performance, and operational comfort level over 2D exoscopes. The relative impact of visualization aids on surgical proficiency gradually weakens as the participants' residency duration increases.

Bur Hole-Based Resections of Intrinsic Brain Tumors with Exoscopic Visualization

BACKGROUND

 The primary goal of brain tumor surgery is maximal safe resection while avoiding iatrogenic injury. As surgical technology increases, it is becoming more possible to resect these lesions using minimally invasive approaches. While keyhole surgeries are being advocated, the lower limit of these approaches is unclear. Bur hole-based approaches may represent a standardized minimally invasive approach. The exoscope may provide increased visualization over standard microscopic visualization, making this approach possible. This approach has yet to be described strictly for intra-axial brain tumors.

MATERIAL AND METHODS

 All patients who underwent a bur hole-based surgery of an intra-axial tumor with exoscopic visualization by the senior author from January 2018 to December 2019 were prospectively identified and patient information and outcomes were collected.

RESULTS

 Fifteen consecutive patients underwent surgical resection of an intrinsic brain tumor using a bur hole-based approach with exoscopic visualization. The average ± standard deviation age was 57.9 ± 24.2 years. The pathology was a metastatic brain tumor in eight patients (53%), low-grade glioma in four patients (27%), and high-grade glioma in three patients (20%). The average percent resection was 100 ± 1%, where 14 (93%) underwent gross total resection. Following surgery, the median (interquartile range) Karnofsky performance scale (KPS) score was 90 (90-90), where 11 (73%) and four patients (27%) had improved and stable KPS, respectively. Zero patients had complications. The average length of stay following surgery was 1.4 ± 0.5 days, where nine patients (60%) were discharged on postoperative day 1.

CONCLUSION

 This study shows that intra-axial tumors can be resected through a bur hole-based approach with exoscopic visualization with extensive resection, minimal morbidity, and early discharge rates.

Monitor-based exoscopic 3D4k neurosurgical interventions: a two-phase prospective-randomized clinical evaluation of a novel hybrid device

Background

Promoting a disruptive innovation in microsurgery, exoscopes promise alleviation of physical strain and improved image quality through digital visualization during microneurosurgical interventions. This study investigates the impact of a novel 3D4k hybrid exoscope (i.e., combining digital and optical visualization) on surgical performance and team workflow in preclinical and clinical neurosurgical settings.

Methods

A pre-clinical workshop setting has been developed to assess usability and implementability through skill-based scenarios (neurosurgical participants n = 12). An intraoperative exploration in head and spine surgery (n = 9) and a randomized clinical study comparing ocular and monitor mode in supratentorial brain tumor cases (n = 20) followed within 12 months. Setup, procedure, case characteristics, surgical performance, and user experience have been analyzed for both ocular group (OG) and monitor group (MG).

Results

Brain tumor cases using frontal, frontoparietal, or temporal approaches have been identified as favorable use cases for introducing exoscopic neurosurgery. Mean monitor distance and angle were 180 cm and 10°. Surgical ergonomics when sitting improved significantly in MG compared with OG (P = .03). Hand-eye coordination required familiarization in MG. Preclinical data showed a positive correlation between lateral camera inclination and impact on hand-eye coordination (r_s = 0.756, P = .01). There was no significant added surgical time in MG. Image quality in current generation 3D4k monitors has been rated inferior to optic visualization yet awaits updates.

Conclusions

The hybrid exoscopic device can be integrated into established neurosurgical workflows. Currently, exoscopic interventions seem most suited for cranial tumor surgery in lesions that are not deep-seated. Ergonomics improve in monitor mode compared to conventional microsurgery.

Electronic supplementary material

The online version of this article (10.1007/s00701-020-04361-2) contains supplementary material, which is available to authorized users.

Retrosigmoid Approach in the Supine Position Using ORBEYE: A Consecutive Series of 14 Cases

One of the merits of recently introduced exoscopes, including ORBEYE, is that they are superior to a conventional microscope in terms of ergonomic features. Taking advantage of it, the retrosigmoid approach can be performed in the supine position using ORBEYE. We report a consecutive series of 14 operations through the retrosigmoid approach in the supine position using ORBEYE. Fourteen consecutive patients who underwent surgery through the retrosigmoid approach for cerebellopontine (CP) angle lesions in the supine position using ORBEYE were targeted, and surgical outcomes and complications were examined. We evaluated the posture of the operator and the surgical field during this approach compared with those using a conventional microscope. In all 14 cases, all operative procedures were accomplished only using the ORBEYE. There were no operative complications due to this approach. Using ORBEYE, even when the angle of the operative visual axis was horizontal, the operators could manipulate in a comfortable posture. They were not forced to be in an uncomfortable posture that extended their arms, as is often the case with a conventional microscope. Therefore, they could use shorter surgical instruments. As the cerebellum shifted downward with gravity even using slight retraction during this approach, the working space of the surgical field was easily secured. Through this approach, the operators can perform stable microsurgery of CP angle lesions in a comfortable posture. This approach can reduce the burden on the operator and the patient, leading to a refined surgical procedure.

Combined transoral exoscope and OArm-assisted approach for craniovertebral junction surgery: Light and shadows in single-center experience with improving technologies

Background

The introduction of recent innovations in the field of intraoperative imaging and neuronavigation, such as OArm Stealth Station, allows to obtain crucial intraoperative data by performing safer and controlled surgical procedures. As part of the improvement of surgical visual magnification and wide expansion of surgical corridors, the 3D-4K exoscope (EX) represents nowadays an interesting and useful tool. Transoral approach (TOA) represents the historical gold standard direct microsurgical route to ventral craniovertebral junction (CVJ).

Methods

We herein report a preliminary experience on 6 cases of 33 patients operated by TOA concerning the simultaneous application of OArm with Stealth Navigation system (Medtronic, Memphis, TN) and imaging system along with the 3D-4K EXs in TOA for the treatment of CVJ pathologies.

Results

Neither intraoperative neurophysiological changes nor postoperative infections occurred, but a neurological improvement was evident in all the patients. A complete decompression along with stable instrumentation and fusion of the CVJ was accomplished in all cases at the maximum follow-up (mean: 16.8 months).

Conclusions

With EX, the role of surgeon become self-sufficient with a better individual surgical freedom compared to endoscopic surgery and excellent 3D vision and magnification. OArm allows an absolutely reliable intraoperative support for a more effective CVJ decompression. Nevertheless, with OArm-assisted neuronavigation, it can be difficult to navigate C1 lateral masses and C2 isthmi, and to convert 3D into 2D real-time navigation, it can become quite complicate. Finally, the association of EX and OArm appears more time consuming compared to the old fashion one.

Brain Metastases: A Modern Multidisciplinary Approach

Brain metastases (BM) are the most common intracranial neoplasm and represent a major clinical challenge across many medical disciplines. The incidence of BM is increasing, largely due to improvements in primary disease therapeutics conferring greater systemic control, and advancements in neuroimaging techniques and availability leading to earlier diagnosis. In recent years, the landscape of BM treatment has changed significantly with the advent of personalized targeted chemotherapies and immunotherapy, the adoption of focal radiotherapy (RT) for higher intracranial disease burden, and the implementation of new surgical strategies. The increasing permutations of options available for the treatment of patients diagnosed with BM necessitate coordinated care by a multidisciplinary team. This review discusses the current treatment regimens for BM as well as examines the salient features of a modern multidisciplinary approach.

Techniques for Open Surgical Resection of Brain Metastases

Brain metastases are the most common intracranial tumor and a leading cause of morbidity and mortality for patients with systemic cancer. En bloc surgical resection of brain metastases improves survival, local recurrence rates, and functional independence in patients with up to three metastases and controlled extracranial disease. Modern techniques and technologies provide the neurosurgeon with minimally invasive approaches, such as keyhole craniotomies and tubular retractors. Preoperative planning for tumors located in eloquent regions includes mapping with functional MRI and diffusion tensor imaging, and intraoperative mapping and monitoring with electrophysiologic techniques under general or awake anesthesia to preserve normal neurologic function.

Minimally Invasive Surgical Outcomes for Deep-Seated Brain Lesions Treated with Different Tubular Retraction Systems: A Systematic Review and Meta-Analysis

BACKGROUND

Minimally invasive surgery using tubular retractors was developed to minimize injury of surrounding brain during the removal of deep-seated lesions. No evidence supports the superiority of any available tubular retraction system in the treatment of these lesions. We conducted a systematic review and meta-analysis to evaluate outcomes and complications after the resection of deep-seated lesions with tubular retractors and among available systems.

METHODS

A PRISMA compliant systematic review was conducted on PubMed, Embase, and Scopus to identify studies in which tubular retractors were used to resect deep-seated brain lesions in patients ≥18 years old.

RESULTS

The search strategy yielded 687 articles. Thirteen articles complying with inclusion criteria and quality assessment were included in the meta-analysis. A total of 309 patients operated on between 2008 and 2018 were evaluated. The most common lesions were gliomas (n = 127), followed by metastases (n = 101) and meningiomas (n = 19). Four different tubular retractors were used: modified retractors (n = 121, 39.1%); METRx (n = 60, 19.4%); BrainPath (n = 92, 29.7%); and ViewSite Brain Access System (n = 36,11.7%). Estimated gross total resection rate was 75% (95% confidence interval, 69%-80%; I² = 9%), whereas the estimated complication rate was 9% (95% confidence interval: 6%-14%; I² = 0%). None of the different brain retraction systems was found to be superior regarding extent of resection or complications on multiple comparisons (P > 0.05).

CONCLUSIONS

Tubular retractors represent a promising tool to achieve maximum safe resection of deep-seated brain lesions. However, there does not seem to be a statistically significant difference in extent of resection or complication rates among tubular retraction systems.

Minimally invasive trans-sulcal parafascicular surgical resection of cerebral tumors: translating anatomy to early clinical experience

The minimally invasive port-based trans-sulcal parafascicular surgical corridor (TPSC) has incrementally evolved to provide a safe, feasible, and effective alternative to access subcortical and intraventricular pathologies. A detailed anatomical foundation is important in mitigating cortical and white matter tract injury with this corridor. Thus, the aims of this study are (1) to provide a detailed anatomical construct and overview of TPSCs and (2) to translate an anatomical framework to early clinical experience. Based on regional anatomical constraints, suitable parafascicular entry points were identified and described. Fiber tracts at both minimal and increased risks for each corridor were analyzed. TPSC-managed cases for metastatic or primary brain tumors were retrospectively reviewed. Adult patients 18 years or older with Karnofsky Performance Status (KPS) ≥ 70 were included. Subcortical brain metastases between 2 and 6 cm or primary brain tumors between 2 and 5 cm were included. Patient-specific corridors and trajectories were determined using MRI-tractography. Anatomy: The following TPSCs were described and translated to clinical practice: superior frontal, inferior frontal, inferior temporal, intraparietal, and postcentral sulci. Clinical: Eleven patients (5 males, 6 females) were included (mean age = 52 years). Seven tumors were metastatic, and 4 were primary. Gross total, near total, and subtotal resection was achieved in 7, 3, and 1 patient(s), respectively. Three patients developed intraoperative complications; all recovered from their intraoperative deficits and returned to baseline in 30 days. A detailed TPSC anatomical framework is critical in conducting safe and effective port-based surgical access. This review may represent one of the few early translational TPSC studies bridging anatomical data to clinical subcortical and intraventricular surgical practice.

Minimally Invasive Parafascicular Surgical Approach for the Management of a Pediatric Third Ventricular Ependymoma: Case Report and Review of Literature

BACKGROUND

Minimally invasive parafascicular surgery (MIPS) has evolved into a safe alternative to access deep-seated subcortical and intraventricular pathologies. We present a case of a port-mediated resection of a pediatric third ventricular tumor.

CASE DESCRIPTION

The patient is a 7-year-old boy who presented with worsening headache, nausea, vomiting, dizziness, unsteady gait, photophobia, and blind spots with positional changes. Magnetic resonance imaging (MRI) scan revealed a large isointense mass, with areas of hyperintensities suggestive of intratumoral hemorrhage, centered in the posterior segment of the third ventricle with extension into the aqueduct of Sylvius. The superior frontal sulcus was used as an access corridor for the port to the frontal horn of the lateral ventricle en route to the third ventricle. Intraoperative visualization was aided with a 3-dimensional exoscopic system. After cannulation, the tumor was seen within the foramen of Monro and tethered to the thalamostriate vein. The tumor was removed completely, with the exception of small residual attached to the thalamostriate vein, which was left intentionally. A flexible endoscope was placed through the port to verify the absence of residual along the superior wall of the third ventricle. Intraoperative MRI scan confirmed presence of residual, along with normal postoperative changes, including pneumocephalus. Postoperative MRI scan revealed cortical recovery along the sulcal path and resolution of ventriculomegaly.

CONCLUSIONS

The patient improved from baseline, with no remaining visual deficits, headaches, or balance issues. Pathology reported a World Health Organization grade II tanycytic ependymoma. To our knowledge, few cases have reported the utilization of port-based MIPS in pediatric patients.

Microsurgery "Under the Eaves" Using ORBEYE: A Case of Dural Arteriovenous Fistula of the Anterior Cranial Fossa

BACKGROUND

One of the merits of exoscopes, including ORBEYE, is that they are superior to a microscope in terms of ergonomic features. We report a case of dural arteriovenous fistula (dAVF) that was cured by direct surgery using the ergonomic advantages of ORBEYE.

CASE DESCRIPTION

A 78-year-old man was found to have dAVF of the anterior cranial fossa incidentally. We performed direct surgery via bifrontal craniotomy. Because the frontal sinus was large, we reserved the frontal bone-like eaves in order not to open the frontal sinus. The vertex of his head was sufficiently down to shift the frontal lobe downward with gravity. During surgery, we set the angle of the operative visual axis of ORBEYE approximately horizontal to avoid the reserved frontal bone. We performed a stable operation using ORBEYE in a comfortable posture.

CONCLUSIONS

ORBEYE facilitates ergonomic microsurgery, even under the eaves, with the angle of the operative visual axis approximately horizontal using gravity.

The exoscope in neurosurgery: an innovative "point of view". A systematic review of the technical, surgical and educational aspects

BACKGROUND

The introduction of operative microscopes (OMs) is the most important revolution in modern microneurosurgery, as a result of the implementation of lighting and magnification of the surgical field and of the capability to dissect the microneurovascular structures. Recently, the advent of video telescopic intraoperative microscopes or exoscopes (EX) has enlarged these perspectives in neurosurgery.

OBJECTIVE

To systematically review all the pertinent literature.

METHODS

We systematically reviewed the pertinent literature and collected all the reported experience with EX use in neurosurgery. Quantitative and qualitative data, along with the authors' opinions and concerns, were recorded and analyzed. A comparison with the OM was also considered.

RESULTS

Twenty-nine studies reporting surgical procedures on 574 patients were included in the study. Data analysis was categorized in 3 groups, representing technical, surgical, and educational aspects. The EX is largely considered superior or equivalent to OM in many features, such as the surgeon's ergonomic comfort, educational opportunities, image quality, magnification, lighting, and costs. However, some surgeons still prefer the OM, especially for its better stereoscopic vision.

CONCLUSIONS

The EX has been emerging as an alternative to the OM for performing many cranial, spinal, and peripheral neurosurgical procedures. Despite some limitations, this new optical device presents many features that can be considered as an evolution of the OM. In future years, larger studies will confirm these preliminary impressions.

Contemporary Surgical Management of Deep-Seated Metastatic Brain Tumors Using Minimally Invasive Approaches

A subset of metastatic brain tumors occurs in deep-seated locations. Accessing and resecting these lesions can be associated with significant morbidity because it involves large craniotomies, extensive white matter dissection, prolonged retraction, and risk of inadvertent tissue injury. As a result, only palliative treatment options are typically offered for these lesions including observation, needle biopsies, and/or radiation therapy. With the development of new surgical tools and techniques, minimally invasive techniques have allowed for the treatment of these lesions previously associated with significant morbidity. These minimally invasive techniques include laser interstitial thermal therapy and channel-based resections.