Keyhole Neurosurgery Research Articles

Minimally invasive keyhole craniotomies for microsurgical clipping of cerebral aneurysms: comparative meta-analysis of the mini-pterional and supraorbital keyhole approaches.

Axel Perneczky is responsible for conceptualizing the "keyhole" philosophy as a new paradigm of minimal invasiveness within cranial neurosurgery. Keyhole neurosurgery aims to limit approach-related traumatization and minimize brain retraction while still enabling the neurosurgeon to achieve operative goals. The supraorbital keyhole craniotomy (SOKC) and minipterional (pterional keyhole, PKC) approaches have become mainstays for clipping intracranial aneurysms. While studies have compared these approaches to the traditional pterional craniotomy for clipping cerebral aneurysms, head-to-head comparisons of these workhorse keyhole approaches remain limited. The authors queried three databases per PRISMA guidelines to identify all studies comparing the SOKC to the PKC for microsurgical clipping of cerebral aneurysms. Of 148 unique studies returned on initial query, a total of 5 studies published between 2013 and 2019 met inclusion criteria. Where applicable, quantitative meta-analysis was performed via the Mantel-Haenszel method using Review Manager v5.4 (Nordic Cochrane Centre, Cochrane Collaboration, Copenhagen, Denmark). Risk of bias (ROB) was assessed using the Cochrane ROBINS-I tool, and all studies were assigned a Level of Evidence (I-V). Across all five studies, the mean age ranged from 53.0 to 57.5 years old, and the cohort consisted of more females (n = 403, 60.6%) than males. The proportion of patients presenting with ruptured aneurysmal SAH was comparable between the SOKC and PKC cohorts (p = 0.43). Clipping rate [defined as the rate of successful aneurysm clip deployment with successful intraoperative occlusion] (OR 1.52 [0.49, 4.71], I2 = 0%, p = 0.47), final occlusion rates (OR 1.27 [0.37, 4.32], p = 0.70), and operative durations (SMD 0.33 [-0.83. 1.49], I2 = 97%, p = 0.58) were comparable regardless of approach used. Furthermore, rates of intraoperative rupture (OR 1.51 [0.64, 3.55], I2 = 0, p = 0.34), postoperative hemorrhage (OR 1.49 [0.74, 3.01], I2 = 0, p = 0.26), postoperative vasospasm (OR 0.94 [0.49, 1.80], I2 = 63, p = 0.86), and postoperative infection (OR 0.70 [0.16, 2.99], I2 = 0%, p = 0.63) were equivocal across SOKC and PKC cohorts. The PKC and SOKC approaches appear to afford comparable outcomes when used for open microsurgical clipping of cerebral aneurysms in select patients with both ruptured and unruptured aneurysms. Both are associated with excellent clipping and occlusion rates, minimal perioperative complication profiles, and favorable postoperative neurologic outcomes. Further investigations are merited so clinicians can further parse out the indications and contraindications for each keyhole approach.

Minimally Invasive Approaches in Reoperations after Conventional Craniotomies : Case Series.

Reoperations are part of neurosurgical practice. In these cases, an already formed craniotomy seems the most logical and appropriate. However, reoperations via large approaches can be quite traumatic for the patient. Then minimally invasive approaches, being less traumatic, can be a good alternative. We describe 7 consecutive patients who underwent reoperations using minimally invasive approaches in the areas of conventional craniotomies. Surgical Theater® visualization platform was used for preoperative planning. The study evaluated the size of surgical approach, surgical efficacy, and the presence of complications. The size of a minimally invasive craniotomy was significantly smaller than that of a conventional approach. The preoperative goals were achieved in all described cases. There were no complications in the early postoperative period. Although the anatomy of the operated brain region in reoperations is altered, keyhole approaches can be successfully used with the support of preoperative planning and intraoperative neuronavigation. Given that the goals of reoperations may differ from those of the primary surgery, and a large approach is more traumatic for the patient, minimally invasive craniotomy can be considered as a good alternative. The successful use of minimally invasive approaches in areas of conventional craniotomies reinforces the philosophy of keyhole neurosurgery. In cases where goals can be achieved using small approaches, it makes no sense to use large conventional ones. Minimally invasive approaches can be successfully used during reoperations in patients after conventional craniotomies.

Supraorbital eyebrow approach: A single-center experience.

Keyhole neurosurgery is the notion of safely removing brain and skull base lesions through smaller and more precise openings that lessen collateral damage to the surrounding scalp, brain, blood vessels, and nerves. The traditional frontal and pterional approaches require large craniotomies and this predisposes patients to significant and avoidable morbidity. With the growing expectation for minimally invasive surgery, we present our experience with the supraorbital keyhole craniotomy for surgical lesions in the anterior cranial fossa and parasellar regions. We retrospectively analyzed and evaluated all cases of neoplastic, vascular, trauma, and infective pathologies of the anterior fossa and parasellar regions treated using a keyhole approach, the supraorbital eyebrow (SOE) approach from January 2018 to June 2022. Treatment outcomes were evaluated based on pathology. A total of 50 patients underwent a SOE craniotomy during the study period (28 females and 22 males). Their average age ranged from 12 to 86 years, with a mean age of 47.4 years. All patients had anterior skull base and/or anterior frontal lobe pathologies: (23 tumors, 17 ruptured aneurysms, five traumatic frontal hematomas, three extradural empyema, one cerebral cavernous malformation, and one traumatic frontal skull base fracture with dural tear and CSF leak). Gross total tumor resection was achieved in 87% of cases (13 meningiomas of which six were giant, three gliomas, two craniopharyngiomas, and two cerebral metastases). Clip ligation occlusion rate for our aneurysm cases was 100% and intraoperative rerupture was observed in three cases. Mean ICU stay was 2.2 days for the entire series. The overall 30-day mortality rate for our series was 16% (eight deaths). This was highest in the ruptured aneurysm subgroup, with all 5 mortality cases in the aneurysmal subgroup presenting as World Federation of Neurological Surgeons (WFNS) grades ≥ III. 4 of the deaths were in WFNS IV and V patients. The most frequent perioperative complication was transient periorbital swelling which resolved within 7 days. It was observed in 18 of the 50 patients. The next common complications in descending frequency were eyebrow alopecia (three cases), supraorbital hypoesthesia (two cases), CSF leak (two cases), and surgical site infection (one case). There was one approach-related intraoperative complication secondary to carotid injury in a giant meningioma redo case. Conversion to a larger craniotomy was never necessary. Clinical outcome for our cases was evaluated according to the Modified Rankin Scale (mRS) at 3-month postsurgery. A good clinical outcome (mRS ≤ 2) was achieved for 78% of our patients. The SOE approach craniotomy is an effective minimally invasive approach for various pathologies of the anterior cranial base and parasellar regions. With experience, giant tumors and complex vascular pathology can be addressed with this keyhole approach.

Minimally invasive keyhole techniques for resection of giant intracranial tumors

BackgroundWhile keyhole neurosurgery is increasingly utilized in the operating room, there are few reports regarding the use of keyhole techniques to resect giant intracranial tumors. The feasibility and technique of that were discussed in this paper.MethodsWe retrospectively reviewed 95 consecutive patients who were admitted to our service between February 2012 and September 2017 with a maximum intracranial tumor diameter >5 cm. Keyhole approaches were used to resect these tumors in each case, including supraorbital, subtemporal, suboccipital, retromastoid, frontal, temporal, occipital, parietal, pterional, a combined temporo-parietal keyhole approach, and an approach via the longitudinal fissure.ResultsWe achieved gross total resection in 68/95 cases (71.6%) and subtotal resection in 27/95 cases (28.4%). No surgical death or severe disabilities such as coma and limb dyskinesia occurred following surgery. At the time of discharge, 8 patients had complications related to impaired cranial nerve function. In addition, 2 patients developed hydrocephalus requiring ventriculo-peritoneal shunt placement, and 4 patients developed a postoperative CSF leak requiring surgical intervention.ConclusionWith meticulous design and reasonable selection, resection of giant intracranial tumors utilizing minimally invasive keyhole approaches can be done safely with satisfactory surgical outcomes.

Inverse Reinforcement Learning Intra-Operative Path Planning for Steerable Needle.

This paper presentsa safe and effective keyhole neurosurgery intra-operative planning framework for flexible neurosurgical robots. The framework is intended to support neurosurgeons during the intra-operative procedure to react to a dynamic environment. The proposed system integrates inverse reinforcement learning path planning algorithm combined with 1) a pre-operative path planning framework for fast and intuitive user interaction, 2) a realistic, time-bounded simulator based on Position-based Dynamics (PBD) simulation that mocks brain deformations due to catheter insertion and 3) a simulated robotic system. Simulation results performed on a human brain dataset show that the inverse reinforcement learning intra-operative planning method can guide a steerable needle with bounded curvature to a predefined target pose with an average targeting error of 1.34 ± 0.52 (25 th = 1.02, 75 th = 1.36) mm in position and 3.16 ± 1.06 (25 th = 2, 75 th = 4.94) degrees in orientation under a deformable simulated environment, with a re-planning time of 0.02 sec and a success rate of 100%. With this work, we demonstrate that the presented intra-operative steerable needle path planner is able to avoid anatomical obstacles while optimising surgical criteria. The results demonstrate that the proposed method is fast and can securely steer flexible needles with high accuracy and robustness.

Position-Based Dynamics Simulator of Brain Deformations for Path Planning and Intra-Operative Control in Keyhole Neurosurgery

Many tasks in robot-assisted surgery require planning and controlling manipulators' motions that interact with highly deformable objects. This study proposes a realistic, time-bounded simulator based on Position-based Dynamics (PBD) simulation that mocks brain deformations due to catheter insertion for pre-operative path planning and intra-operative guidance in keyhole surgical procedures. It maximizes the probability of success by accounting for uncertainty in deformation models, noisy sensing, and unpredictable actuation. The PBD deformation parameters were initialized on a parallelepiped-shaped simulated phantom to obtain a reasonable starting guess for the brain white matter. They were calibrated by comparing the obtained displacements with deformation data for catheter insertion in a composite hydrogel phantom. Knowing the gray matter brain structures' different behaviors, the parameters were fine-tuned to obtain a generalized human brain model. The brain structures' average displacement was compared with values in the literature. The simulator's numerical model uses a novel approach with respect to the literature, and it has proved to be a close match with real brain deformations through validation using recorded deformation data of in-vivo animal trials with a mean mismatch of 4.73$\pm$2.15%. The stability, accuracy, and real-time performance make this model suitable for creating a dynamic environment for KN path planning, pre-operative path planning, and intra-operative guidance.

Mini Fronto-Orbital Approach: "Window Opening" Towards the Superomedial Orbit - A Virtual Reality-Planned Anatomic Study.

Surgical approaches to the orbit are challenging and require combined multispecialist skills. Considering its increasing relevance in neurosurgical practice, keyhole surgery could be also applied to this field. However, mastering a minimally invasive approach necessitates an extended learning curve. For this reason, virtual reality (VR) can be effectively used for planning and training in this demanding surgical technique. To validate the mini fronto-orbital (mFO) approach to the superomedial orbit, using VR planning and specimen dissections, conjugating the principles of skull base and keyhole neurosurgery. Three-dimensional measurements were performed thanks to Surgical Theater (Surgical Theater© LLC), and then, simulated craniotomies were implemented on cadaver specimens. The mFO approach affords optimal exposure and operability in the target area and reduced risks of surrounding normal tissue injuries. The eyebrow skin incision, the minimal soft-tissue retraction, the limited temporalis muscle dissection and the single-piece craniotomy, as planned with VR, are the key elements of this minimally invasive approach. Furthermore, the "window-opening" cotton-tip intraorbital dissection technique, based on widening surgical corridors between neuromuscular bundles, provides a safe orientation and a deep access inside the orbit, thereby significantly limiting the risk of jeopardizing neurovascular structures. The mFO approach associated to the window-opening dissection technique can be considered safe, effective, suitable, and convenient for treating lesions located in the superomedial orbital aspect, up to the orbital apex.

Risk assessment methodology for trajectory planning in keyhole neurosurgery using genetic algorithms.

Preoperative assessment to find the safest trajectory in keyhole neurosurgery can reduce post operative complications. We introduced a novel preoperative risk assessment semiautomated methodology based on the sum of N maximum risk values using a generic genetic algorithm for the safest trajectory search. A set of candidates trajectories were found for two surgical procedures. The trajectories search is done using a risk map considering the proximity of voxels within risk structures in multiple points and a genetic algorithm to avoid an exhaustive search. The trajectories were validated by a group of neurosurgeons. The trajectories obtained with the proposal method were shorter in 5% and have greater distance from the voxels within the blood vessels in 4.7%. The use of genetic algorithm (GA) speeds up the search for the safest trajectory, decreasing in 99.9% the time required for an exhaustive search.

Full-field swept-source optical coherence tomography and neural tissue classification for deep brain imaging.

Optical coherence tomography can differentiate brain regions with intrinsic contrast and at a micron scale resolution. Such a device can be particularly useful as a real‐time neurosurgical guidance tool. We present, to our knowledge, the first full‐field swept‐source optical coherence tomography system operating near a wavelength of 1310 nm. The proof‐of‐concept system was integrated with an endoscopic probe tip, which is compatible with deep brain stimulation keyhole neurosurgery. Neuroimaging experiments were performed on ex vivo brain tissues and in vivo in rat brains. Using classification algorithms involving texture features and optical attenuation, images were successfully classified into three brain tissue types.

Neuroendoscopy to Achieve Superior Glioma Resection Outcomes.

Neuroendoscopy to Achieve Superior Glioma Resection Outcomes.

Enhanced markerless surgical robotic guidance system for keyhole neurosurgery

Enhanced markerless surgical robotic guidance system for keyhole neurosurgery

Risk map generation for keyhole neurosurgery using fuzzy logic for trajectory evaluation

Planning safe trajectories in keyhole neurosurgery requires a high level of accuracy in order to reach small anatomical structures in operations such as biopsies, deep brain stimulation and other therapy/diagnostic procedures. In this study, we propose a user interface that assists the neurosurgeon to select the entry point of the procedure using an atlas which displays the risk of the different linear trajectories from the head surface skin to the target. The risk assignment is carried out in two main steps, a weighted sum which depends on the distance of a single voxel to other risk structures and a second criteria using fuzzy rules to take into account other qualities such as length, which is the main contribution of this work. As a result, we present risk maps of two targets and visualize the less risky trajectories according to the system.

Keyhole Cisternal Navigational Resection of an Inner Falx Meningioma

Objective: The keyhole concept in neurosurgery has remained mostly limited to transcranial endoscope-assisted microsurgery or limited-sized keyhole craniotomies. In contrast, documentation of keyhole surgery, as described by Yaşargil, regarding no traumatization to the normal neural, arterial, and venous structures has appeared relatively less in the medical literature, under the term keyhole neurosurgery. Microsurgical resection of falcine meningiomas, although not infrequent, poses technical challenges related to the tumor’s anatomic relationships with the superior sagittal sinus, inferior sagittal sinus, callosomarginal arteries, pericallosal arteries, and neural structures of the medial aspects of the hemispheres. Case Description: A 35-year-old female patient with an anterior inner falcine meningioma and frontal multiple cortical veins draining into superior sagittal sinus is presented. The tumor was totally removed using a very small gap without scarifying any cortical vein. Postoperatively, the patient did very well. Conclusions: The microneurosurgical technique of navigation through aquatic cisternal corridors for surgical access is a minimally invasive technique permitting surgical manipulations through very small gaps and preserves normal neural and vascular structures.

Da Vinci robot-assisted keyhole neurosurgery: a cadaver study on feasibility and safety.

The goal of this cadaver study was to evaluate the feasibility and safety of da Vinci robot-assisted keyhole neurosurgery. Several keyhole craniotomies were fashioned including supraorbital subfrontal, retrosigmoid and supracerebellar infratentorial. In each case, a simple durotomy was performed, and the flap was retracted. The da Vinci surgical system was then used to perform arachnoid dissection towards the deep-seated intracranial cisterns. It was not possible to simultaneously pass the 12-mm endoscope and instruments through the keyhole craniotomy in any of the approaches performed, limiting visualization. The articulated instruments provided greater dexterity than existing tools, but the instrument arms could not be placed in parallel through the keyhole craniotomy and, therefore, could not be advanced to the deep cisterns without significant clashing. The da Vinci console offered considerable ergonomic advantages over the existing operating room arrangement, allowing the operating surgeon to remain non-sterile and seated comfortably throughout the procedure. However, the lack of haptic feedback was a notable limitation. In conclusion, while robotic platforms have the potential to greatly enhance the performance of transcranial approaches, there is strong justification for research into next-generation robots, better suited to keyhole neurosurgery.

Optimal invasive key-hole neurosurgery with a miniaturized 3D chip on the tip: Microendoscopic device

Objective:The goal of the performed study was to evaluate the possibility of a three-dimensional endoscope to become a combined microscope-endoscope device in one. We analyzed the ergonomy of the device, the implementation into the surgical workflow, the image quality, and the future perspectives such devices could have for the next generation of neurosurgeons.Materials and Methods:Within 6 months, 22 patients (10 male, 12 female, 20-65 age) underwent surgery in neuroaxis using the new 3D-microendoscope (ME). The new 3D-ME has (a) the ability to visualize the surgical field from out- to inside with all advantages offered by a microscope, and in the same moment, (b) its design is like a small diameter endoscope that allows stereoscopic views extracorporal, intracorporal, and panoramic “para-side” of the lesion.Results:In general, transcranial 3D-“microendoscopy” was performed in all patients with high-resolution 3D quality. No severe complications were observed intra- or postoperatively. With the addition of depth perception, the anatomic structures were well seen and observed.Conclusion:The 3D-microendoscopy is a very promising surgical concept associated with new technological developments. The surgeon is able to switch to a modern visualization instrument reaching the most optimal surgical approach without compromising safety, effectiveness, and visual information.

Robotics in Keyhole Transcranial Endoscope-Assisted Microsurgery

Over the past decade, advances in image guidance, endoscopy, and tube-shaft instruments have allowed for the further development of keyhole transcranial endoscope-assisted microsurgery, utilizing smaller craniotomies and minimizing exposure and manipulation of unaffected brain tissue. Although such approaches offer the possibility of shorter operating times, reduced morbidity and mortality, and improved long-term outcomes, the technical skills required to perform such surgery are inevitably greater than for traditional open surgical techniques, and they have not been widely adopted by neurosurgeons. Surgical robotics, which has the ability to improve visualization and increase dexterity, therefore has the potential to enhance surgical performance. To evaluate the role of surgical robots in keyhole transcranial endoscope-assisted microsurgery. The technical challenges faced by surgeons utilizing keyhole craniotomies were reviewed, and a thorough appraisal of presently available robotic systems was performed. Surgical robotic systems have the potential to incorporate advances in augmented reality, stereoendoscopy, and jointed-wrist instruments, and therefore to significantly impact the field of keyhole neurosurgery. To date, over 30 robotic systems have been applied to neurosurgical procedures. The vast majority of these robots are best described as supervisory controlled, and are designed for stereotactic or image-guided surgery. Few telesurgical robots are suitable for keyhole neurosurgical approaches, and none are in widespread clinical use in the field. New robotic platforms in minimally invasive neurosurgery must possess clear and unambiguous advantages over conventional approaches if they are to achieve significant clinical penetration.

Reduced risk trajectory planning in image‐guided keyhole neurosurgery

The authors present and evaluate a new preoperative planning method and computer software designed to reduce the risk of candidate trajectories for straight rigid tool insertion in image-guided keyhole neurosurgery. Trajectories are computed based on the surgeon-defined target and a candidate entry point area on the outer head surface on preoperative CT/MRI scans. A multiparameter risk card provides an estimate of the risk of each trajectory according to its proximity to critical brain structures. Candidate entry points in the outer head surface areas are then color-coded and displayed in 3D to facilitate selection of the most adequate point. The surgeon then defines and/or revised the insertion trajectory using an interactive 3D visualization of surrounding structures. A safety zone around the selected trajectory is also computed to visualize the expected worst-case deviation from the planned insertion trajectory based on tool placement errors in previous surgeries. A retrospective comparative study for ten selected targets on MRI head scans for eight patients showed a significant reduction in insertion trajectory risk. Using the authors' method, trajectories longer than 30 mm were an average of 2.6 mm further from blood vessels compared to the conventional manual method. Average planning times were 8.4 and 5.9 min for the conventional technique and the authors' method, respectively. Neurosurgeons reported improved understanding of possible risks and spatial relations for the trajectory and patient anatomy. The suggested method may result in safer trajectories, shorter preoperative planning time, and improved understanding of risks and possible complications in keyhole neurosurgery.

Accurate multi-robot targeting for keyhole neurosurgery based on external sensor monitoring

Robotics has recently been introduced in surgery to improve intervention accuracy, to reduce invasiveness and to allow new surgical procedures. In this framework, the ROBOCAST system is an optically surveyed multi-robot chain aimed at enhancing the accuracy of surgical probe insertion during keyhole neurosurgery procedures. The system encompasses three robots, connected as a multiple kinematic chain (serial and parallel), totalling 13 degrees of freedom, and it is used to automatically align the probe onto a desired planned trajectory. The probe is then inserted in the brain, towards the planned target, by means of a haptic interface. This paper presents a new iterative targeting approach to be used in surgical robotic navigation, where the multi-robot chain is used to align the surgical probe to the planned pose, and an external sensor is used to decrease the alignment errors. The iterative targeting was tested in an operating room environment using a skull phantom, and the targets were selected on magnetic resonance images. The proposed targeting procedure allows about 0.3 mm to be obtained as the residual median Euclidean distance between the planned and the desired targets, thus satisfying the surgical accuracy requirements (1 mm), due to the resolution of the diffused medical images. The performances proved to be independent of the robot optical sensor calibration accuracy.

Robotic and artificial intelligence for keyhole neurosurgery: The ROBOCAST project, a multi-modal autonomous path planner

The robot and sensors integration for computer-assisted surgery and therapy (ROBOCAST) project (FP7-ICT-2007-215190) is co-funded by the European Union within the Seventh Framework Programme in the field of information and communication technologies. The ROBOCAST project focuses on robot- and artificial-intelligence-assisted keyhole neurosurgery (tumour biopsy and local drug delivery along straight or turning paths). The goal of this project is to assist surgeons with a robotic system controlled by an intelligent high-level controller (HLC) able to gather and integrate information from the surgeon, from diagnostic images, and from an array of on-field sensors. The HLC integrates pre-operative and intra-operative diagnostics data and measurements, intelligence augmentation, multiple-robot dexterity, and multiple sensory inputs in a closed-loop cooperating scheme including a smart interface for improved haptic immersion and integration. This paper, after the overall architecture description, focuses on the intelligent trajectory planner based on risk estimation and human criticism. The current status of development is reported, and first tests on the planner are shown by using a real image stack and risk descriptor phantom. The advantages of using a fuzzy risk description are given by the possibility of upgrading the knowledge on-field without the intervention of a knowledge engineer.

Microsurgical anatomy and clinical application of infratentorial supracerebellar keyhole approach

To explore the feasibility of applying the infratentorial supracerebellar keyhole approach for removing tumors of pineal region. Infratentorial supracerebellar keyhole approach was performed in 16 cadaveric heads with intracranial vessels perfused by colored latex. The microscopic structure was observed. The anatomic structure was measured with Stryker Navigation System and the data were analyzed with the SPSS 10.0 software. And further, infratentorial supracerebellar keyhole approach was performed in 11 clinical cases with tumors located in the posterior third ventricle and pineal region, based on the individualized imaging features. Only the central group bridging veins on the cerebellum tentorial surface needed to be sacrificed under infratentorial supracerebellar keyhole approach, and other vessels could be preserved well. The distance between the bridging veins of both left and right medial group could reach (35 +/- 6) mm when they were fully dissected, thus offering enough surgical space for applying this keyhole approach. When the culmen of cerebellum was retracted, the pineal body, Galen vein and its tributary, quadrigeminal bodies, even trochlear nerve could be observed. When the underlayer choroid of the third ventricular roof was dissected medially and inferiorly to the posterior choroidal artery, the posterior third ventricle could be reached. If the tentorium of cerebellum was cut open between the straight sinus and the lateral sinus, the surgical field could be enlarged anteriorly and superiorly to the longitudinal fissure region above the tentorium. Eight of the 11 pineal region tumors sized 2-5 cm in diameter were totally removed, and 3 were subtotally resected. For one case, posterior cranial fossa decompression and ventriculoperitoneal shunt were performed postoperatively. Another one patient suffered from transient mutism and steady fixation after surgery. Other patients had no adverse effect. Infratentorial supracerebellar keyhole approach can be applied for removing the pineal region tumors without interfering the adjacent deep venous system, and can enter the third ventricle in a nearly non-traumatic way. If necessary the tentorium can be cut open to expose supra-tentorial structures. It can be regarded as a better choice for surgeries in this region.