Initial Experience with Exoscopic-Based Intraoperative Indocyanine Green Fluorescence Video Angiography in Cerebrovascular Surgery: A Preliminary Case Series Showing Feasibility, Safety, and Next-Generation Handheld Form-Factor

Exoscopic Clipping of a Ruptured Posterior Communicating Artery Aneurysm Through a Minipterional Approach: 2-Dimensional Operative Video

Posterior communicating artery (PCoA) aneurysms represent approximately 15% to 25% of intracranial aneurysms and carry an estimated risk of rupture of 44%.1-4 Surgical clipping of PCoA aneurysms bears notable challenges associated with operating in a confined space with limited visualization of deep structures.1,5 We illustrate the case of a 54-year-old woman who presented with a seven-hour course of intense headaches, vomiting and loss of consciousness. Her neurological examination revealed she had a 4/5 left-sided hemiparesis, a Glasgow coma scale score of 12, and a Hunt and Hess score of 3. A head computed tomography scan without contrast showed subarachnoid hemorrhage in the basal cisterns and Sylvian fissures (Fisher grade 3). Digital subtraction angiography and three-dimensional reconstruction imaging revealed a right bilobed saccular PCoA aneurysm of 4.8 × 5.9 mm projecting anterior-inferiorly. After consideration of her clinical course and aneurysmal features, she underwent a right minipterional craniotomy for exoscopic clipping of the aneurysm neck. The patient tolerated the procedure well, her hemiparesis improved, and she was discharged with a modified Rankin scale score of 1 on postoperative day 3. Exoscopy offered high image quality and expanded 3-dimensional view with digital zoom during the aneurysm repair.6,7 Although evidence suggests exoscopy is non-inferior to microscopy regarding surgery duration, safety, and outcomes, the capability of providing operator ergonomy during surgery is a worth-noting advantage.8 IRB and patient consent declaration: This study was exempt from the Institution Review Board because patient consent was granted for the use of clinical information, images, and operative videos. The patient consented to the procedure, and the participants and any identifiable individuals consented to publication of his/her image.

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.

Ultrahigh-Definition-3-Dimensional Exoscope-Assisted Clipping of a Right Middle Cerebral Artery Unruptured Aneurysm with Indocyanine Green Video Angiography: Operative Video

Ultrahigh-definition 3-dimensional exoscopes represent an excellent technologic innovation in contemporary neurosurgery. They combine the advantages of operating microscopes and endoscopes, offering excellent magnification and lighting, maintaining a relatively small footprint and optimal ergonomic features.1-5 One of the most interesting employments of exoscopes in neurosurgery is represented by intracranial vascular surgery. Reports in this field are still limited, but recent experience has shown that ultrahigh definition 3-dimensional exoscopes for aneurysm surgery are noninferior to operating microscopes for surgery duration, complication rate, and patient outcomes.6 In addition, many intraoperative techniques such as the indocyanine green videoangiography (ICG-VA) have been successfully implemented to exoscope-based surgery.7 We present herein the case of a 66-year-old woman that came to our attention for the incidental finding of 3 unruptured brain aneurysms. After neurosurgical consultation, the one located at the right middle cerebral artery bifurcation was considered eligible for surgery.8,9 As shown in Video 1, ICG-VA was employed after permanent clipping to allow immediate quality assurance of occlusion and distal vessel integrity. Postoperative course was uneventful, and follow-up examinations demonstrated the complete occlusion of the aneurysm. This report highlights the feasibility of exoscopic-based ICG-VA in vascular neurosurgery, given its ease of use, ergonomics, and excellent quality of vision provided to both surgeons and operating staff.

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.

3D Exoscopes are Noninferior to Operating Microscopes in Aneurysm Surgery: Comparative Single-Surgeon Series of 52 Consecutive Cases

OBJECTIVE

The literature on exoscope use in cerebrovascular neurosurgery is scarce, mainly comprising small case series and focused on visualization quality and ergonomics. As these devices become widely used, direct comparison to the operating microscope regarding efficacy and patient safety is necessary.

METHODS

Fifty-two consecutive clipping procedures, performed by 1 senior vascular neurosurgeon, were analyzed. Either an operating microscope with a mouth switch (25 cases with 27 aneurysms; 13 ruptured) or a three-dimensional exoscope with a foot switch (27 cases with 34 aneurysms; 6 ruptured) were used. Durations of major surgical stages, number of device adjustments, numbers of clip repositionings and clips implanted were extracted from surgical videos. Demographic data, imaging characteristics, clinical course and outcomes were extracted from digital patient records.

RESULTS

Duration of surgery and different stages did not differ between devices, except for final site inspection. The number of device adjustments was higher with the exoscope. With progressive experience in exoscope use, the number of device adjustments increased significantly, whereas surgery duration remained unchanged. Favorable outcome (modified Rankin Scale score 0-2) was observed in 80% and 88% of patients in the microscope and exoscope groups, respectively. Ischemic events were found in 2 patients in each group; no other complications occurred.

CONCLUSIONS

In aneurysm clipping, three-dimensional exoscopes are noninferior to operating microscopes in terms of surgery duration, safety, and outcomes, based on our limited series. Progressive experience enables the surgeon to perform significantly more device adjustments within the same amount of surgical time.

Lateral Supracerebellar Infratentorial Approach for Superior Oblique Myokymia: A Case Series

BACKGROUND

Few reports have shown that superior oblique myokymia (SOM) may result from vascular compression of the trochlear nerve and may be curable using microvascular decompression (MVD).

OBJECTIVE

To report the clinical characteristics and surgical treatment of 2 cases of SOM and provide a review of the related literature.

METHODS

Two patients with SOM were treated using MVD with the lateral supracerebellar infratentorial approach. The patients underwent diagnostic magnetic resonance imaging and three-dimensional fusion imaging preoperatively. A lateral suboccipital craniotomy was performed in the park-bench position. The trochlear nerve and branches of the superior cerebellar artery were confirmed after opening the cerebellomesencephalic fissure over the tentorial surface of the cerebellum. The vessel, which compressed the root exit zone of the trochlear nerve, was transposed far from the nerve and attached to the surface of the midbrain using Teflon felt and fibrin glue.

RESULTS

The first case showed compression on both the ventral and rostral sides of the trochlear nerve root exit zone, and the second showed compression only on the ventral side. Large bridging veins on the tentorial surface of the cerebellum complicated the approach in the second case. Postoperatively, both patients had immediate and complete resolution of symptoms without recurrence at the 24-mo and 17-mo follow-ups, respectively. Five previous reports described the complete resolution of SOM after MVD.

CONCLUSION

A presentation of an intermittent fluttering ocular sensation should prompt magnetic resonance imaging for ipsilateral trochlear nerve compression. The lateral supracerebellar infratentorial approach allows safe and efficacious MVD for SOM.

Evaluation of 3D Robotic-Guided Exoscopic Visualization in Microneurosurgery

Objective

The three-dimensional (3D) exoscope is a novel apparatus introduced in recent years. Although an operating microscope (OM) is customarily used, this novel application offers several advantages. Therefore, this study aimed to determine the feasibility of deploying a robotic-guided 3D-exoscope for microneurosurgery and gauge its subsequent performance.

Methods

The use of a 3D exoscope was compared with that of OM during 16 surgical procedures. Postoperatively, surgeons completed an eight-item Likert-scale satisfaction survey. As a second step, a predefined surgical task was then undertaken by surgeons with varying levels of experience, assessing the time entailed. Two questionnaires, the satisfaction survey and NASA task load index (NASA-TLX), were administered.

Results

During routine procedures, the exoscope proved superior in magnification and ergonomic maintenance, showing inferior image contrast, quality, and illumination. It again ranked higher in magnification and ergonomic maintenance during the suturing task, and the OM excelled in treatment satisfaction and stereoscopic orientation. Workload assessment using the NASA-TLX revealed no difference by modality in the pairwise analysis of all components. At varying levels of experience, beginners bear a significantly higher burden in all principle components than mid-level and expert participants (p = 0.0018). Completion times for the suturing task did not differ (p = 0.22).

Conclusion

The quality of visualization by 3D exoscope seems adequate for treatment and its ergonomic benefit is superior to that of OM. Although experienced surgeons performed a surgical simulation faster under the OM, no difference was evident in NASA-TLX surveys. The 3D exoscope is an excellent alternative to the OM.

Nimodipine reduces delayed cerebral vasospasm after intracranial tumour surgery: A Retrospective Study

Cerebral vasospasm (CVS) is a frequent and serious neurosurgical complication, without sufficient therapy. This retrospective study was performed to analyze if nimodipine can improve prognosis and reduce ischaemia secondary to delayed CVS after intracranial tumour surgery. A retrospective review was performed over the years 2011 to 2012 for patients with an anterior cranial fossa tumour and underwent intracranial tumour surgery. The surgical field was soaked with nimodipine solution or normal saline. Transcranial Doppler ultrasonography was used to measure velocity in the middle cerebral artery (MCA) and the distal extracranial internal carotid artery (eICA). Follow-up was performed using the Glasgow Outcome Scale (GOS) after discharge. There were 94 patients that met the inclusion criteria. They included 50 males and 44 females, with a mean age of 49.6 years. In the nimodipine group, CVS occurred in 13 patients; 9 patients had CVS between 4 and 7 days, and 4 had CVS between 8 and 14 days. In the normal saline group, 19 patients had CVS, 3 presented with CVS within 3 days, 11 between 4-7 days and 5 between 8-14 days. A significant difference in the occurrence of CVS was observed between the two groups. Preoperative and postoperative the MCA velocities were compared, revealing a significant change in the normal saline group but not in the nimodipine group. Nimodipine markedly improves prognosis and significantly reduces ischaemia secondary to delayed CVS after intracranial tumour surgery, as well as the risks of mortality and morbidity.

Comparison of Operating Microscope and Exoscope in a Highly Challenging Experimental Setting

BACKGROUND

The use of a digital three-dimensional (3D) exoscope system in neurosurgery is increasing as an alternative to the operative microscope. The objective of this study was to compare a digital 3D exoscope system with a standard operating microscope as a neurosurgical visualization tool in a highly challenging experimental setting.

METHODS

End-to-side bypass procedures, each at a depth of 9 cm, were performed in a simulation setting. The quality of the task and the depth effect, visualization, magnification, illumination, and ergonomics were evaluated.

RESULTS

No major differences were noted between the microscope and the 3D exoscope in terms of the quality of the work. Working with the 3D exoscope was more time-consuming than working with the microscope. Changing the depth and focus was faster using the operative microscope. The 3D exoscope enabled higher magnification and offered better ergonomic features.

CONCLUSIONS

In a highly challenging experimental setting, comparable procedural quality was found for the microscope and the 3D exoscope. Each visualization tool had advantages and disadvantages. Over time and with technologic advances, the digital 3D exoscope may become the main operative visualization system in microneurosurgery.