Augmented Reality in Superficial Temporal Artery to Middle Cerebral Artery Bypass Surgery: Technical Note

A decade of progress: bringing mixed reality image-guided surgery systems in the operating room

Advancements in mixed reality (MR) have led to innovative approaches in image-guided surgery (IGS). In this paper, we provide a comprehensive analysis of the current state of MR in image-guided procedures across various surgical domains. Using the Data Visualization View (DVV) Taxonomy, we analyze the progress made since a 2013 literature review paper on MR IGS systems. In addition to examining the current surgical domains using MR systems, we explore trends in types of MR hardware used, type of data visualized, visualizations of virtual elements, and interaction methods in use. Our analysis also covers the metrics used to evaluate these systems in the operating room (OR), both qualitative and quantitative assessments, and clinical studies that have demonstrated the potential of MR technologies to enhance surgical workflows and outcomes. We also address current challenges and future directions that would further establish the use of MR in IGS.

Evolution of the meta-neurosurgeon: A systematic review of the current technical capabilities, limitations, and applications of augmented reality in neurosurgery

Background

Augmented reality (AR) applications in neurosurgery have expanded over the past decade with the introduction of headset-based platforms. Many studies have focused on either preoperative planning to tailor the approach to the patient's anatomy and pathology or intraoperative surgical navigation, primarily realized as AR navigation through microscope oculars. Additional efforts have been made to validate AR in trainee and patient education and to investigate novel surgical approaches. Our objective was to provide a systematic overview of AR in neurosurgery, provide current limitations of this technology, as well as highlight several applications of AR in neurosurgery.

Methods

We performed a literature search in PubMed/Medline to identify papers that addressed the use of AR in neurosurgery. The authors screened three hundred and seventy-five papers, and 57 papers were selected, analyzed, and included in this systematic review.

Results

AR has made significant inroads in neurosurgery, particularly in neuronavigation. In spinal neurosurgery, this primarily has been used for pedicle screw placement. AR-based neuronavigation also has significant applications in cranial neurosurgery, including neurovascular, neurosurgical oncology, and skull base neurosurgery. Other potential applications include operating room streamlining, trainee and patient education, and telecommunications.

Conclusion

AR has already made a significant impact in neurosurgery in the above domains and has the potential to be a paradigm-altering technology. Future development in AR should focus on both validating these applications and extending the role of AR.

Augmented Reality in Neurosurgery: A New Paradigm for Training

Augmented reality (AR) involves the overlay of computer-generated images onto the user's real-world visual field to modify or enhance the user's visual experience. With respect to neurosurgery, AR integrates preoperative and intraoperative imaging data to create an enriched surgical experience that has been shown to improve surgical planning, refine neuronavigation, and reduce operation time. In addition, AR has the potential to serve as a valuable training tool for neurosurgeons in a way that minimizes patient risk while facilitating comprehensive training opportunities. The increased use of AR in neurosurgery over the past decade has led to innovative research endeavors aiming to develop novel, more efficient AR systems while also improving and refining present ones. In this review, we provide a concise overview of AR, detail current and emerging uses of AR in neurosurgery and neurosurgical training, discuss the limitations of AR, and provide future research directions. Following the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), 386 articles were initially identified. Two independent reviewers (GH and AC) assessed article eligibility for inclusion, and 31 articles are included in this review. The literature search included original (retrospective and prospective) articles and case reports published in English between 2013 and 2023. AR assistance has shown promise within neuro-oncology, spinal neurosurgery, neurovascular surgery, skull-base surgery, and pediatric neurosurgery. Intraoperative use of AR was found to primarily assist with surgical planning and neuronavigation. Similarly, AR assistance for neurosurgical training focused primarily on surgical planning and neuronavigation. However, studies included in this review utilize small sample sizes and remain largely in the preliminary phase. Thus, future research must be conducted to further refine AR systems before widespread intraoperative and educational use.

Head-Mounted Augmented Reality in the Planning of Cerebrovascular Neurosurgical Procedures: A Single-Center Initial Experience

BACKGROUND

Augmented reality (AR) technology has played an increasing role in cerebrovascular neurosurgery over the last 2 decades. Hence, we aim to evaluate the technical and educational value of head-mounted AR in cerebrovascular procedures.

METHODS

This is a single-center retrospective study of patients who underwent open surgery for cranial and spinal cerebrovascular lesions between April and August 2022. In all cases, the Medivis Surgical AR platform and HoloLens 2 were used for preoperative and intraoperative (preincision) planning. Surgical plan adjustment due to the use of head-mounted AR and subjective educational value of the tool were recorded.

RESULTS

A total of 33 patients and 35 cerebrovascular neurosurgical procedures were analyzed. Procedures included 12 intracranial aneurysm clippings, 6 brain and 1 spinal arteriovenous malformation resections, 2 cranial dural arteriovenous fistula obliterations, 3 carotid endarterectomies, two extracranial-intracranial direct bypasses, two encephaloduroangiosynostosis for Moyamoya disease, 1 biopsy of the superficial temporal artery, 2 microvascular decompressions, 2 cavernoma resections, 1 combined intracranial aneurysm clipping and encephaloduroangiosynostosis for Moyamoya disease, and 1 percutaneous feeder catheterization for arteriovenous malformation embolization. Minor changes in the surgical plan were recorded in 16 of 35 procedures (45.7%). Subjective educational value was scored as "very helpful" for cranial, spinal arteriovenous malformations, and carotid endarterectomies; "helpful" for intracranial aneurysm, dural arteriovenous fistulas, direct bypass, encephaloduroangiosynostosis, and superficial temporal artery-biopsy; and "not helpful" for cavernoma resection and microvascular decompression.

CONCLUSIONS

Head-mounted AR can be used in cerebrovascular neurosurgery as an adjunctive tool that might influence surgical strategy, enable 3-dimensional understanding of complex anatomy, and provide great educational value in selected cases.

Augmented and virtual reality usage in awake craniotomy: a systematic review

Augmented and virtual reality (AR, VR) are becoming promising tools in neurosurgery. AR and VR can reduce challenges associated with conventional approaches via the simulation and mimicry of specific environments of choice for surgeons. Awake craniotomy (AC) enables the resection of lesions from eloquent brain areas while monitoring higher cortical and subcortical functions. Evidence suggests that both surgeons and patients benefit from the various applications of AR and VR in AC. This paper investigates the application of AR and VR in AC and assesses its prospective utility in neurosurgery. A systematic review of the literature was performed using PubMed, Scopus, and Web of Science databases in accordance with the PRISMA guidelines. Our search results yielded 220 articles. A total of six articles consisting of 118 patients have been included in this review. VR was used in four papers, and the other two used AR. Tumour was the most common pathology in 108 patients, followed by vascular lesions in eight patients. VR was used for intraoperative mapping of language, vision, and social cognition, while AR was incorporated in preoperative training of white matter dissection and intraoperative visualisation and navigation. Overall, patients and surgeons were satisfied with the applications of AR and VR in their cases. AR and VR can be safely incorporated during AC to supplement, augment, or even replace conventional approaches in neurosurgery. Future investigations are required to assess the feasibility of AR and VR in various phases of AC.

Current status of augmented reality in cerebrovascular surgery: a systematic review

Augmented reality (AR) is an adjuvant tool in neuronavigation to improve spatial and anatomic understanding. The present review aims to describe the current status of intraoperative AR for the treatment of cerebrovascular pathology. A systematic review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The following databases were searched: PubMed, Science Direct, Web of Science, and EMBASE up to December, 2020. The search strategy consisted of "augmented reality," "AR," "cerebrovascular," "navigation," "neurovascular," "neurosurgery," and "endovascular" in both AND and OR combinations. Studies included were original research articles with intraoperative application. The manuscripts were thoroughly examined for study design, outcomes, and results. Sixteen studies were identified describing the use of intraoperative AR in the treatment of cerebrovascular pathology. A total of 172 patients were treated for 190 cerebrovascular lesions using intraoperative AR. The most common treated pathology was intracranial aneurysms. Most studies were cases and there was only a case-control study. A head-up display system in the microscope was the most common AR display. AR was found to be useful for tailoring the craniotomy, dura opening, and proper identification of donor and recipient vessels in vascular bypass. Most AR systems were unable to account for tissue deformation. This systematic review suggests that intraoperative AR is becoming a promising and feasible adjunct in the treatment of cerebrovascular pathology. It has been found to be a useful tool in the preoperative planning and intraoperative guidance. However, its clinical benefits remain to be seen.

Use of Intraoperative Neuronavigation to Identify Transdural Collaterals in Moyamoya Vasculopathy: A Simple Way to Make It Safer

INTRODUCTION

Transdural collaterals (TC) from the external carotid artery must be preserved when operating on patients with moyamoya vasculopathy. Several techniques have been used to identify the superficial temporal artery (STA) and middle meningeal artery (MMA) during surgery and prevent their damage. However, the use of neuronavigation for this specific purpose has never been described in the literature. We describe an operative case in which neuronavigation was used to preserve the TC (originating from the MMA), detailing our technique step by step and reviewing alternative methods previously reported.

CASE PRESENTATION

A 6-year-old girl with moyamoya disease, who had developed marked bilateral TC from the MMA sparing the middle cerebral artery territory, underwent staged bilateral indirect revascularization surgery. Intraoperative neuronavigation was used to identify the STA and MMA with their main branches during skin incision, craniotomy, and dural opening. The neuronavigation matched the intraoperative findings exactly, and the target structures remained undamaged. The patient was discharged home after both surgeries with no neurological deficits. One year following surgery, the patient has excellent collateralization from both STAs and is asymptomatic and neurologically intact.

CONCLUSION

With the use of intraoperative neuronavigation, the STA, MMA, and their main branches, as well as their relationship to the bone, can be identified and preserved. This approach can help in preventing undesirable injury to TC during surgery and may potentially prevent perioperative stroke in patients with moyamoya vasculopathy undergoing revascularization surgery.

Evaluation of the effect of standard neuronavigation and augmented reality on the integrity of the perifocal structures during a neurosurgical approach

OBJECTIVE

Intracranial minimally invasive procedures imply working in a restricted surgical corridor surrounded by critical structures, such as vessels and cranial nerves. Any damage to them may affect patient outcome. Neuronavigation systems may reduce the risk of such complications. In this study, the authors sought to compare standard neuronavigation (NV) and augmented reality (AR)-guided navigation with respect to the integrity of the perifocal structures during a neurosurgical approach using a novel model imitating intracranial vessels.

METHODS

A custom-made box, containing crisscrossing hard metal wires, a hidden nail at its bottom, and a wooden top, was scanned, fused, and referenced for the purpose of the study. The metal wires and an aneurysm clip applier were connected to a controller, which counted the number of contacts between them. Twenty-three naive participants were asked to 1) use NV to define an optimal entry point on the top, perform the smallest craniotomy possible on the wooden top, and to use a surgical microscope when placing a clip on the nail without touching the metal wires; and 2) use AR to preoperatively define an ideal trajectory, navigate the surgical microscope, and then perform the same task. The primary outcome was the number of contacts made between the metal wires and the clip applier. Secondary outcomes were craniotomy size, and trust in NV and AR to help avoid touching the metal wires, as assessed by a 9-level Likert scale.

RESULTS

The median number of contacts tended to be lower with the use of AR than with NV (AR, median 1 [Q1: 1, Q3: 2]; NV, median 3 [Q1: 1, Q3: 6]; p = 0.074). The size of the target-oriented craniotomy was significantly lower with the use of AR compared with NV (AR, median 4.91 cm2 [Q1: 4.71 cm2, Q3: 7.55 cm2]; and NV, median 9.62 cm2 [Q1: 7.07 cm2; Q3: 13.85 cm2]). Participants had more trust in AR than in NV (the differences posttest minus pretest were mean 0.9 [SD 1.2] and mean -0.3 [SD 0.2], respectively; p < 0.05).

CONCLUSIONS

The results of this study show a trend favoring the use of AR over NV with respect to reducing contact between a clip applier and the perifocal structures during a simulated clipping of an intracranial aneurysm. Target-guided craniotomies were smaller with the use of AR. AR may be used not only to localize surgical targets but also to prevent complications associated with damage to structures encountered during the surgical approach.

Controversies and Advances in Adult Intracranial Bypass Surgery in 2020

Cerebral revascularization utilizing a variety of bypass techniques can provide either flow augmentation or flow replacement in the treatment of a range of intracranial pathologies, including moyamoya disease, intracranial atherosclerotic disease, and complex aneurysms that are not amenable to endovascular or simple surgical techniques. Though once routine, the publication of high-quality prospective evidence, along with the development of flow-diverting stents, has limited the indications for extracranial-to-intracranial (EC-IC) bypass. Nevertheless, advances in imaging, assessment of cerebral hemodynamics, and surgical technique have changed the risk-benefit calculus for EC-IC bypass. New variations of revascularization surgery involving multiple anastomoses, flow preserving solutions, IC-IC constructs, and posterior circulation bypasses have been pioneered for otherwise difficult to treat pathology including giant aneurysms, dolichoectasia, and medically refractory intracranial atherosclerosis. This review provides a practical update on recent advances in adult intracranial bypass surgery.

First experience with augmented reality neuronavigation in endoscopic assisted midline skull base pathologies in children

INTRODUCTION

Endoscopic skull base approaches are broadly used in modern neurosurgery. The support of neuronavigation can help to effectively target the lesion avoiding complications. In children, endoscopic-assisted skull base surgery in combination with navigation systems becomes even more important because of the morphological variability and rare diseases affecting the sellar and parasellar regions. This paper aims to analyze our first experience on augmented reality navigation in endoscopic skull base surgery in a pediatric case series.

PATIENTS AND METHODS

A retrospective review identified seventeen endoscopic-assisted endonasal or transoral procedures performed in an interdisciplinary setting in a period between October 2011 and May 2020. In all the cases, the surgical target was a lesion in the sellar or parasellar region. Clinical conditions, MRI appearance, intraoperative conditions, postoperative MRI, possible complications, and outcomes were analyzed.

RESULTS

The mean age of our patients was 14.5 ± 2.4 years. The diagnosis varied, but craniopharyngiomas (31.2%) were mostly represented. AR navigation was experienced to be very helpful for effectively targeting the lesion and defining the intraoperative extension of the pathology. In 65% of the oncologic cases, a radical removal was proven in postoperative MRI. The mean follow-up was 89 ± 79 months. There were no deaths in our series. No long-term complications were registered; two cerebrospinal fluid (CSF) fistulas and a secondary abscess required further surgery.

CONCLUSION

The implementation of augmented reality to endoscopic-assisted neuronavigated procedures within the skull base was feasible and did provide relevant information directly in the endoscopic field of view and was experienced to be useful in the pediatric cases, where anatomical variability and rarity of the pathologies make surgery more challenging.

Indocyanine green videoangiography for recipient vessel stratification in superficial temporal artery-middle cerebral artery bypass surgery

OBJECTIVE

In superficial temporal artery-middle cerebral artery (STA-MCA) bypass surgery, recipient vessel properties are likely one of the main reasons for bypass failure. In daily practice, most surgeons select the recipient with the largest diameter. However, selection of the ideal recipient remains debatable because there are no objective selection criteria if multiple potential recipients exist. Here, the authors assessed the benefit of using indocyanine green videoangiography (ICG-VA) to optimize recipient vessel selection in patients undergoing STA-MCA bypass surgery for hemodynamic compromise.

METHODS

All patients who had undergone STA-MCA bypass procedures with pre- and postanastomosis ICG-VA between 2010 and 2019 were eligible for inclusion in this study. The primary bypass surgeon was blinded to the preanastomosis ICG-VA. Preanastomosis white-light and ICG-VA images were compared to determine the identifiability of potential recipient vessels and pathological flow patterns. After completion of the anastomosis, a second (postanastomosis) ICG-VA image was used to analyze the flow increase within the chosen recipient based on the vessel diameter, initial recipient blood flow, initial sequence of appearance on ICG-VA, initial blood flow direction within the recipient, and orientation of the bypass graft. ICG-VA, FLOW 800, and intraoperative white-light images, as well as demographic, clinical, and radiographic patient data, were retrospectively analyzed by a clinician who was not directly involved in the patients' care.

RESULTS

Sixty patients underwent 65 STA-MCA bypass procedures with pre- and postanastomosis ICG-VA. The ICG-VA permitted identification of a significantly higher number of potential recipient vessels (median 4, range 1-9) than the white-light images (median 2, range 1-5; p < 0.001), with detection of pathological flow patterns in 20% of all procedures. No association was found between the diameter and blood flow within potential recipients (Spearman r = 0.07, p = 0.69). After bypass grafting, the highest flow increase was noted in recipients with an initially low flow (p < 0.01), a late appearance (p < 0.01), and an initially retrograde flow direction (p = 0.02). Interestingly, flow increase was not significantly influenced by the recipient diameter (p = 0.09) or graft orientation (p = 0.44).

CONCLUSIONS

ICG-VA facilitates identification of potential recipient vessels and detection of pathological flow patterns. Recipients with an initially low flow, a late appearance, and a retrograde flow seem to bear the highest potential for flow increase, possibly due to a higher hemodynamic need for revascularization.