Multiportal Retrograde Endoscopy to Enhance Surgical Target Visualization: A Pilot Study.

Objective Current transnasal endoscopic techniques for sinus and skull base surgery use a single endoscope to provide visualization from one perspective curtailing depth perception and compromising visualization of the instrument-target interface. The view can be blocked by instruments, and collisions between instruments often occur. The objective of this study was to investigate the use of multiportal retrograde endoscopy to provide more accurate manipulation of the surgical target. Design Maxillary antrostomy and frontal sinusotomy were performed on three different cadavers by three different surgeons. A zero-degree rigid endoscope was introduced through the nose for the standard transnasal approach. A flexible endoscope was introduced transorally, directed past the palate superiorly, and then flexed 180 degrees for the retrograde view. Videos of the standard transnasal view from the rigid endoscope and retrograde view from the flexible endoscope were recorded simultaneously. Results All surgeries were able to be performed with dual-screen viewing of the standard and retrograde view. The surgeons noted that they utilized the retrograde view to adjust the location of ends/tips of their instruments. Four surgeons reviewed the videos and individually agreed that the visualization achieved provided a perspective otherwise not attainable with rigid transnasal endoscopy alone. Conclusion High-quality visualization of surgical targets such as the frontal or maxillary ostia can be challenging with rigid endoscopes alone. Multiportal retrograde endoscopy provides proof of concept that additional views of a surgical target can be achieved. Additional work is needed to further develop indications, techniques, and generalizability to targets beyond those investigated here.

Reducing annotating load: Active learning with synthetic images in surgical instrument segmentation.

Accurate instrument segmentation in the endoscopic vision of minimally invasive surgery is challenging due to complex instruments and environments. Deep learning techniques have shown competitive performance in recent years. However, deep learning usually requires a large amount of labeled data to achieve accurate prediction, which poses a significant workload. To alleviate this workload, we propose an active learning-based framework to generate synthetic images for efficient neural network training. In each active learning iteration, a small number of informative unlabeled images are first queried by active learning and manually labeled. Next, synthetic images are generated based on these selected images. The instruments and backgrounds are cropped out and randomly combined with blending and fusion near the boundary. The proposed method leverages the advantage of both active learning and synthetic images. The effectiveness of the proposed method is validated on two sinus surgery datasets and one intraabdominal surgery dataset. The results indicate a considerable performance improvement, especially when the size of the annotated dataset is small. All the code is open-sourced at: https://github.com/HaonanPeng/active_syn_generator.

Five-year outcome of a staged giant Shamblin type III carotid body tumor excision.

Giant carotid body tumors, defined as those >8 cm in size, are extremely rare. Definitive surgical management is a complex undertaking because these large tumors tend to have grown to envelop cranial nerves and the carotid artery, and few data exist regarding the long-term outcomes for these patients. We present the case of a patient with bilateral giant carotid body tumors who underwent staged embolization and excision of a >10-cm carotid body tumor. After 5 years of follow-up, we demonstrated that elective open repair can provide long-term symptomatic relief. We describe and illustrate the crucial steps and considerations regarding the excision of complex Shamblin type III carotid body tumors.

Automatic summarization of endoscopic skull base surgical videos through object detection and hidden Markov modeling.

Endoscopic endonasal surgery is a medical procedure that utilizes an endoscopic video camera to view and manipulate a surgical site accessed through the nose. Despite these surgeries being video recorded, these videos are seldom reviewed or even saved in patient files due to the size and length of the video file. Editing to a manageable size may necessitate viewing 3 h or more of surgical video and manually splicing together the desired segments. We suggest a novel multi-stage video summarization procedure utilizing deep semantic features, tool detections, and video frame temporal correspondences to create a representative summarization. Summarization by our method resulted in a 98.2% reduction in overall video length while preserving 84% of key medical scenes. Furthermore, resulting summaries contained only 1% of scenes with irrelevant detail such as endoscope lens cleaning, blurry frames, or frames external to the patient. This outperformed leading commercial and open source summarization tools not designed for surgery, which only preserved 57% and 46% of key medical scenes in similar length summaries, and included 36% and 59% of scenes containing irrelevant detail. Experts agreed that on average (Likert Scale = 4) that the overall quality of the video was adequate to share with peers in its current state.

Operative Technique and Complication Management in a Case of Giant Esthesioneuroblastoma Resected by a Combined Transcranial and Endonasal Endoscopic Approach: Technical Case Report.

BACKGROUND AND IMPORTANCE: Esthesioneuroblastoma (ENB) is a rare anterior skull base tumor derived from olfactory epithelium. There are very few operative videos in the literature demonstrating the surgical resection techniques for giant ENB because of their rarity and complexity. In this technical report, we demonstrate the microsurgical resection of a very large and complex high-grade ENB, initially deemed unresectable, through a bifrontal craniotomy and extended subfrontal approach combined with an endonasal endoscopic approach. CLINICAL PRESENTATION: A 34-year-old woman presented with headaches, nasal congestion, and bloody nasal drainage. MRI showed a large nasal cavity mass with extension into the anterior cranial fossa and bifrontal lobes. There was significant bifrontal edema causing headaches and abutting the optic nerves. Initial management with surgical resection was offered to the patient for local tumor control and to preserve her vision. A combined bifrontal craniotomy and endonasal transsphenoidal approach was used for resecting this giant tumor. After achieving gross total resection, we reconstructed the anterior skull base in layers. She developed several postoperative complications which were appropriately managed. CONCLUSION: We demonstrate the surgical resection of a giant ENB through a combined transcranial and endonasal endoscopic approach. We discuss the several postoperative complications in this complex case and the lessons learned.

The "Crista Ovale": A Reliable Anatomical Landmark in Transorbital Endoscopic Approaches to the Middle Cranial Fossa.

BACKGROUND: Transorbital endoscopic approaches (TOEAs) have emerged as adjunct and alternatives for accessing the middle cranial fossa (MCF). Nuances of the skull base anatomy from a ventral transorbital endoscopic viewpoint remain to be fully described. OBJECTIVE: To assess the anatomy of the "crista ovale" (COv), described transcranially as the midsubtemporal ridge (MSR), from a ventral transorbital perspective and evaluate its role as a landmark in TOEA to the MCF. METHODS: Lateral TOEAs to the MCF were performed in 20 adult cadaveric heads (40 sides). The presence of the COv/MSR was evaluated under endoscopic visualization. Anatomic relationships between COv/MSR and surrounding structures were assessed. The presence of COv/MSR was also examined in 30 cadaveric head computed tomography (CT) scans (60 sides). RESULTS: The COv/MSR was identified in 98% (39/40) of sides at the MCF, as 1 of 4 major configurations. The COv/MSR was found anterolateral to the foramen ovale and foramen spinosum (mean distance: 9.2 ± SD 2.4 mm and 12.3 ± SD 2.6 mm, respectively) directly anterior or anteromedial to the petrous apex (mean distance: 26.2 ± SD 2.6 mm) and at a mean 47.6 ± SD 4.7 mm from the approach's surgical portal. It was recognized in 95% (57/60) of CT scans. CONCLUSION: The COv/MSR can be readily identified during TOEA to the MCF and on CT. It serves as a reliable landmark to localize the foramen ovale, foramen spinosum, and petrous apex. Further studies may confirm its surgical significance in transorbital endoscopic procedures.

Endoscopic Paramaxillary Approach to the Infratemporal Fossa and Pterygomaxillary Space: Computer Modeling Analysis and Clinical Series.

Objective Several different open and endoscopic approaches for the pterygomaxillary space and infratemporal fossa have been described. Limitations to these approaches include restricted exposure of the infratemporal fossa and difficult surgical manipulation. Study Design Consecutive clinical cases utilizing a novel approach to access lesions in the infratemporal fossa and pterygomaxillary space were reviewed. Data was collected on pathology, lesion location, and surgical approach(es) performed. Computer modeling was performed to analyze the full extent of surgical access provided by the paramaxillary approach to the range of target locations. Results Ten consecutive cases met inclusion criteria. Surgical access to the target lesion was achieved in all cases. Computer modeling of the approach derived the anatomical boundaries of the paramaxillary approach. Wide access to the posterior maxilla, and lateral or medial to the mandibular condyle allows for variability in endoscopic angles and access to more medial pterygomaxillary space lesions. The lateral extent is limited proximally only by the extent of cheek/soft tissue retraction and by the zygomatic arch more superiorly. The superior limit of dissection is at the temporal line. Conclusion The endoscopic paramaxillary approach is a transoral minimally disruptive approach to the ITF and PS that provides excellent surgical exposure for resection of lesions involving these areas. Compared with previously described endoscopic approaches, there are no external incisions; tumor manipulation is straightforward without angled endoscopy, and all areas of the infratemporal fossa and pterygomaxillary space can be accessed.

A case series of crossbow injury to the head highlighting the importance of an interdisciplinary management approach.

BACKGROUND: Penetrating crossbow head injuries are rare with no clear consensus regarding the optimal management paradigm for such injuries. We present three cases of crossbow injury to the head, with emphasis on the need for a comprehensive multidisciplinary management plan. CASE DESCRIPTION: Three cases are presented of patients presenting with self-inflicted penetrating crossbow to head injuries. All three patients presented with intact neurological exam. A comprehensive multidisciplinary plan was created for all three cases with subsequent successful removal of the arrows. All three patients were discharged home with modified Rankin scale score of <2. CONCLUSION: Penetrating crossbow brain injuries are rare and require complex management. A comprehensive management strategy is necessary to manage these injuries. Moreover, careful consideration of factors such as the arrow trajectory, complexity of the injuries, and availability of the required expertise is important to increase the chances of success.

Real-time virtual intraoperative CT in endoscopic sinus surgery.

PURPOSE: Endoscopic sinus surgery (ESS) is typically guided under preoperative computed tomography (CT), which increasingly diverges from actual patient anatomy as the surgery progresses. Studies have reported that the revision surgery rate in ESS ranges between 28 and 47%. This paper presents a method that can update the preoperative CT in real time to improve surgical completeness in ESS. APPROACH: The work presents and compares three novel methods that use instrument motion data and anatomical structures to predict surgical modifications in real time. The methods use learning techniques, such as nonparametric filtering and Gaussian process regression, to correlate surgical modifications with instrument tip positions, tip trajectories, and instrument shapes. Preoperative CT image sets are updated with modification predictions to serve as a virtual intraoperative CT. RESULTS: The three methods were compared in eight ESS cadaver cases, which were performed by five surgeons and included the following representative ESS operations: maxillary antrostomy, uncinectomy, anterior and posterior ethmoidectomy, and sphenoidotomy. Experimental results showed accuracy metrics that were clinically acceptable with dice similarity coefficients > 86%, with F-score > 92% and precision > 89.91% in surgical completeness evaluation. Among the three methods, the tip trajectory-based estimator had the highest precision of 96.87%. CONCLUSIONS: This work demonstrated that virtually modified intraoperative CT scans improved the consistency between the actual surgical scene and the reference model, and could lead to improved surgical completeness in ESS. Compared to actual intraoperative CT scans, the proposed method has no impact on existing surgical protocols, does not require extra hardware, does not expose the patient to radiation, and does not lengthen time under anesthesia.

Frontal Sinus Fractures.

Management of frontal sinus fractures is controversial with no universally accepted treatment protocol. Goals of management are to correct aesthetic deformity, preserve sinus function when it is deemed salvageable, prevent sequela related to the injury, and minimize complications associated with intervention. Studies suggest that frontal sinus injuries, including disruption of the nasofrontal outflow tract (NFOT), can be managed nonoperatively in many cases. Advances in the utilization of endoscopic techniques have led to an evolution in management that reduces the need for open procedures, which have increased morbidity compared with endoscopic approaches. We employ a minimally disruptive protocol that treats the majority of fractures nonoperatively with serial clinical and radiographic examinations to assess for sinus aeration. Surgical intervention is reserved for the most severely displaced and comminuted posterior table fractures and unsalvageable NFOTs utilizing endoscopic approaches whenever possible.

Factors Associated with Ocular Injury in Orbital Fracture Patients: Who Requires Urgent Ophthalmic Evaluation?

Importance: Create validated criteria to identify orbital fracture patients at higher risk for significant ocular injuries. Objective: Determine history and physical examination findings in orbital fracture patients who are associated with ocular injury and warrant urgent assessment by an ophthalmologist. Design, Setting, and Participants: Retrospective chart review of 535 adult orbital fracture patients evaluated at a Level I emergency department between 2014 and 2017, without prior history of orbital fracture, ocular injury, or ocular/orbital surgery. Main Outcomes and Measure: Presence of ocular injury. Results: In total, 195 (36%) patients had an ocular injury. Those with and without ocular injury were compared in a multivariate logistic regression model including demographics, fracture characteristics, injury mechanism, and physical examination findings. Visual acuity change, radiographic retrobulbar hemorrhage, abnormal pupillary reaction, and inability to open the injured eye all had significant associations with ocular injury when other findings were controlled. Conclusion: This study shows a significant association between ocular injury and visual acuity change, retrobulbar hemorrhage, abnormal pupillary reaction, and inability to open the injured eye. These factors can help triage when to obtain an urgent ophthalmology consult.

Automated atlas-based segmentation for skull base surgical planning.

PURPOSE: Computational surgical planning tools could help develop novel skull base surgical approaches that improve safety and patient outcomes. This defines a need for automated skull base segmentation to improve the usability of surgical planning software. The objective of this work was to design and validate an algorithm for atlas-based automated segmentation of skull base structures in individual image sets for skull base surgical planning. METHODS: Advanced Normalization Tools software was used to construct a synthetic CT template from 6 subjects, and skull base structures were manually segmented to create a reference atlas. Landmark registration followed by Elastix deformable registration was applied to the template to register it to each of the 30 trusted reference image sets. Dice coefficient, average Hausdorff distance, and clinical usability scoring were used to compare the atlas segmentations to those of the trusted reference image sets. RESULTS: The mean for average Hausdorff distance for all structures was less than 2 mm (mean for 95th percentile Hausdorff distance was less than 5 mm). For structures greater than 2.5 mL in volume, the average Dice coefficient was 0.73 (range 0.59-0.82), and for structures less than 2.5 mL in volume the Dice coefficient was less than 0.7. The usability scoring survey was completed by three experts, and all structures met the criteria for acceptable effort except for the foramen spinosum, rotundum, and carotid artery, which required more than minor corrections. CONCLUSION: Currently available open-source algorithms, such as the Elastix deformable algorithm, can be used for automated atlas-based segmentation of skull base structures with acceptable clinical accuracy and minimal corrections with the use of the proposed atlas. The first publicly available CT template and anterior skull base segmentation atlas being released (available at this link: http://hdl.handle.net/1773/46259 ) with this paper will allow for general use of automated atlas-based segmentation of the skull base.

Computer-Aided Rhinoplasty Using a Novel "navigated" Nasal Osteotomy Technique: A Pilot Study.

OBJECTIVE: To describe the surgical technique of navigation-guided nasal osteotomies and assess feasibility of this technique for treating complex nasal bone deformities in reconstructive rhinoplasty. METHODS: A retrospective chart review was performed in order to identify patients who underwent computer-aided rhinoplasty from August 2014 to February 2017. Inclusion criteria were nasal bone deformities on computed-tomography (CT) that correlated with specific nasal complaints. All patients underwent computer-aided rhinoplasty with navigation-guided nasal osteotomies using a standard navigation system. Osteotomies were performed using real-time visualization on the navigation screen. Additional soft tissue procedures were performed as needed. Medical records were reviewed for presenting symptoms, radiologic and operative findings, and postoperative course. Cosmetic outcomes were subjectively based on patients' standard 6-view photo-documentation from pre- and post-operative timepoints. RESULTS: Twenty-one patients were included in the study; 8 were revision cases and 3 had mild-to-moderate hemifacial microsomia. Fifteen were completely closed procedures. No cases were opened because of inadequate visualization or difficulty accessing bony pathology. Mean (range) follow up was 98.6 (6-559) days. There were no intra-operative complications, unplanned admissions or re-admissions, or iatrogenic cosmetic complications (ie, "inverted V" or "saddle nose" deformities). Two patients required revision. One was after suffering nasal trauma within 4 weeks of initial rhinoplasty. The second underwent further correction of a deformity that required a costochondral graft. Both experienced good final results. CONCLUSIONS: Computer-aided rhinoplasty is safe and feasible for treating complex nasal deformities using standard navigation systems.

Endoscopic Orbital and Periorbital Approaches in Minimally Disruptive Skull Base Surgery.

Endoscopic surgery of the orbit, periorbital region, and adjacent areas of the anterior and middle cranial fossae and brain has gained significant popularity over the last decade. These procedures are now being used at multiple institutions internationally with a success and safety record that has been demonstrated to be at par with or better than other techniques. The approaches provide minimally disruptive, scarless access to regions that previously required extensive open operations with significant retraction of critical neurovascular structures leading to prolonged morbidity and hospitalization. This paper will describe the basic techniques of these approaches, how they can be used alone or in multiportal (para- and contraportal) technique and guide the reader to resources for further learning.