CSO (Canadian Society of Otolaryngology - Head & Neck Surgery) position paper on rhinologic and skull base surgery during the COVID-19 pandemic

Optimizing Surgical Care Amidst COVID-19: A Scoping Review of Practices and Policies

BACKGROUND

The coronavirus disease (COVID-19) pandemic significantly disrupted surgical care worldwide, affecting different specialties in various ways. Lockdowns, surges in COVID-19 cases, and changes in hospital policies notably impacted patient attendance, management practices, and access to surgical services. This scoping review examines the adverse impacts of the COVID-19 pandemic on surgical services and the policies adopted to address these care barriers.

METHODS

We conducted a comprehensive literature review using the preferred reporting items for systematic reviews and meta-analyses extension for scoping reviews (PRISMA-ScR) guidelines. Our search, spanning 31 December 2019, to 29 January 2023, focused on understanding the multifaceted impacts of COVID-19 on surgical services, particularly across different specialties.

RESULTS

An analysis of 75 articles indicated that the pandemic challenged surgeons worldwide to maintain a balance between delivering emergency and elective surgical care, and implementing safety measures against viral transmission. There was a marked decline in the surgical volume, leading to extended waitlists and decreased operating theater usage. Strategies such as prioritizing medically necessary and time-sensitive surgeries and integrating telemedicine have emerged as pivotal for ensuring the continuity of urgent care. Despite the reduced rates, essential surgeries such as appendectomies and cancer-related operations continued, yet faced hurdles, including reduced staffing, limited operating theater capacity, and complications in patient transfers.

CONCLUSIONS

This review emphasizes the steep reduction in surgical service utilization at the beginning of the pandemic and emergence of new compounded barriers. Policies that designated surgeries as essential, and focused on equitable and timely access, were effective. Incorporating these findings into post-pandemic assessments and future planning is crucial to sustain adequate surgical care during similar health emergencies.

Risk of SARS-CoV-2 contagion in otolaryngology specialists

COVID-19 has rapidly spread in the past two years with a profound impact on otolaryngological activities, which has undergone radical transformation to guarantee diagnostic and therapeutic procedures mainly in oncology and urgent patients, while ensuring protection for healthcare personnel and patients. During the initial phases of the pandemic, scheduled visits and elective surgeries were postponed leading to a delay in the diagnosis and treatment of several diseases, including head and neck cancer, with a shift toward more advanced cancer stages and more aggressive treatments. Aerosol and droplets are the main routes of transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), thus leading to a high risk of contagion during otolaryngology visits and surgery. Therefore, the correct use of personal protective equipment (PPE) and attention to procedure-specific risks and measures to avoid contagion are of utmost importance for healthcare professionals, and especially for those dealing with otolaryngology diseases. This narrative review highlights that otolaryngological activity implies a high risk of contagion during outpatient visit, surgery, or urgent conditions. The correct use of PPE, evaluation of procedure-specific risks and reduction of non-urgent procedures are considered the main strategies to limit contagion.

Pediatric Coronavirus Disease 2019: Clinical Features and Management

There is a lack of clarity regarding management of COVID-19 infection in children. This review aims to summarize the key clinical presentations and management of Pediatric COVID-19. The Medline database was searched for seminal articles and guidelines on COVID-19 presentation and management in children less than 18 years of age. COVID-19 has a lower incidence (1-5% of reported cases worldwide), causes milder disease with lower need for intensive care admission and lower mortality rate (0-0.7%) in children compared with adults. Multisystem inflammatory syndrome is a rare but severe complication in children. Majority of patients require supportive care including adequate hydration, nutrition and antipyretics. Supplemental oxygen therapy should be given in moderate to severe cases with all precautions to prevent air-borne COVID-19 spread. Steroids may be helpful in severe cases. Anticoagulation is indicated in moderate to severe cases with risk factors. More data on the efficacy and safety of antivirals and immunomodulators in children is needed.

Pediatric Coronavirus Disease 2019: Clinical Features and Management

There is a lack of clarity regarding management of COVID-19 infection in children. This review aims to summarize the key clinical presentations and management of Pediatric COVID-19. The Medline database was searched for seminal articles and guidelines on COVID-19 presentation and management in children less than 18 years of age. COVID-19 has a lower incidence (15% of reported cases worldwide), causes milder disease with lower need for intensive care admission and lower mortality rate (00.7%) in children compared with adults. Multisystem inflammatory syndrome is a rare but severe complication in children. Majority of patients require supportive care including adequate hydration, nutrition and antipyretics. Supplemental oxygen therapy should be given in moderate to severe cases with all precautions to prevent air-borne COVID-19 spread. Steroids may be helpful in severe cases. Anticoagulation is indicated in moderate to severe cases with risk factors. More data on the efficacy and safety of antivirals and immunomodulators in children is needed.

Volumetric Measurements of Brain Shift Using Intraoperative Cone-Beam Computed Tomography: Preliminary Study

BACKGROUND

Cerebrospinal fluid leakage and ventricular compression during open surgery may lead to brain deformation called brain shift. Brain shift may affect intraoperative navigation that is based on image-based preoperative planning. Tools to correct or predict these anatomic modifications can be important to maintain precision during open guided neurosurgery.

OBJECTIVE

To obtain a reliable intraoperative volumetric deformation vector field describing brain shift during intracranial neurosurgical procedures.

METHODS

We acquired preoperative and intraoperative cone-beam computed tomography enhanced with intravenous injection of iodine contrast. These data sets were preprocessed and elastically registered to obtain the volumetric brain shift deformation vector fields.

RESULTS

We obtained the brain shift deformation vector field in 9 cases. The deformation fields proved to be highly nonlinear, particularly around the ventricles. Interpatient variability was considerable, with a maximum deformation ranging from 8.1 to 26.6 mm and a standard deviation ranging from 0.9 to 4.9 mm.

CONCLUSION

Contrast-enhanced cone-beam computed tomography provides a feasible technique for intraoperatively determining brain shift deformation vector fields. This technique can be used perioperatively to adjust preoperative planning and coregistration during neurosurgical procedures.

Intraoperative image-guided transoral robotic surgery: pre-clinical studies

BACKGROUND

Adequate resection of oropharyngeal neoplasms with transoral robotic surgery (TORS) poses multiple challenges, including difficulty with access, inability to palpate the tumor, loss of landmarks, and intraoperative patient positioning with mouth retractor and tongue extended creating significant tissue distortion from preoperative imaging.

METHODS

This study evaluates a workflow integrating intraoperative cone beam computed tomography (CBCT) for image-guided TORS through robotic experimentation locating 8-10 embedded targets in five porcine tongues and a cadaveric head phantom, conducted under various modes of visualization and integration of preoperative/intraoperative imaging.

RESULTS

A statistically significant improvement in mean target localization error was achieved for both the porcine tongue ((9.8 ± 4.0) mm vs. (5.3 ± 1.3) mm, P-value = 0.0151) and cadaver ((11.2 ± 5.0) mm vs. (5.8 ± 2.5) mm P-value = 0.0189) in experiments comparing scenarios simulating current standard-of-care practice and the proposed image guidance system.

CONCLUSION

Intraoperative image guidance with augmentation of critical surgical structures has the potential to improve target localization for TORS.

Extra-dimensional Demons: a method for incorporating missing tissue in deformable image registration

PURPOSE

A deformable registration method capable of accounting for missing tissue (e.g., excision) is reported for application in cone-beam CT (CBCT)-guided surgical procedures. Excisions are identified by a segmentation step performed simultaneous to the registration process. Tissue excision is explicitly modeled by increasing the dimensionality of the deformation field to allow motion beyond the dimensionality of the image. The accuracy of the model is tested in phantom, simulations, and cadaver models.

METHODS

A variant of the Demons deformable registration algorithm is modified to include excision segmentation and modeling. Segmentation is performed iteratively during the registration process, with initial implementation using a threshold-based approach to identify voxels corresponding to "tissue" in the moving image and "air" in the fixed image. With each iteration of the Demons process, every voxel is assigned a probability of excision. Excisions are modeled explicitly during registration by increasing the dimensionality of the deformation field so that both deformations and excisions can be accounted for by in- and out-of-volume deformations, respectively. The out-of-volume (i.e., fourth) component of the deformation field at each voxel carries a magnitude proportional to the excision probability computed in the excision segmentation step. The registration accuracy of the proposed "extra-dimensional" Demons (XDD) and conventional Demons methods was tested in the presence of missing tissue in phantom models, simulations investigating the effect of excision size on registration accuracy, and cadaver studies emulating realistic deformations and tissue excisions imparted in CBCT-guided endoscopic skull base surgery.

RESULTS

Phantom experiments showed the normalized mutual information (NMI) in regions local to the excision to improve from 1.10 for the conventional Demons approach to 1.16 for XDD, and qualitative examination of the resulting images revealed major differences: the conventional Demons approach imparted unrealistic distortions in areas around tissue excision, whereas XDD provided accurate "ejection" of voxels within the excision site and maintained the registration accuracy throughout the rest of the image. Registration accuracy in areas far from the excision site (e.g., > ∼5 mm) was identical for the two approaches. Quantitation of the effect was consistent in analysis of NMI, normalized cross-correlation (NCC), target registration error (TRE), and accuracy of voxels ejected from the volume (true-positive and false-positive analysis). The registration accuracy for conventional Demons was found to degrade steeply as a function of excision size, whereas XDD was robust in this regard. Cadaver studies involving realistic excision of the clivus, vidian canal, and ethmoid sinuses demonstrated similar results, with unrealistic distortion of anatomy imparted by conventional Demons and accurate ejection and deformation for XDD.

CONCLUSIONS

Adaptation of the Demons deformable registration process to include segmentation (i.e., identification of excised tissue) and an extra dimension in the deformation field provided a means to accurately accommodate missing tissue between image acquisitions. The extra-dimensional approach yielded accurate "ejection" of voxels local to the excision site while preserving the registration accuracy (typically subvoxel) of the conventional Demons approach throughout the rest of the image. The ability to accommodate missing tissue volumes is important to application of CBCT for surgical guidance (e.g., skull base drillout) and may have application in other areas of CBCT guidance.

TREK: an integrated system architecture for intraoperative cone-beam CT-guided surgery

PURPOSE

A system architecture has been developed for integration of intraoperative 3D imaging [viz., mobile C-arm cone-beam CT (CBCT)] with surgical navigation (e.g., trackers, endoscopy, and preoperative image and planning data). The goal of this paper is to describe the architecture and its handling of a broad variety of data sources in modular tool development for streamlined use of CBCT guidance in application-specific surgical scenarios.

METHODS

The architecture builds on two proven open-source software packages, namely the cisst package (Johns Hopkins University, Baltimore, MD) and 3D Slicer (Brigham and Women's Hospital, Boston, MA), and combines data sources common to image-guided procedures with intraoperative 3D imaging. Integration at the software component level is achieved through language bindings to a scripting language (Python) and an object-oriented approach to abstract and simplify the use of devices with varying characteristics. The platform aims to minimize offline data processing and to expose quantitative tools that analyze and communicate factors of geometric precision online. Modular tools are defined to accomplish specific surgical tasks, demonstrated in three clinical scenarios (temporal bone, skull base, and spine surgery) that involve a progressively increased level of complexity in toolset requirements.

RESULTS

The resulting architecture (referred to as "TREK") hosts a collection of modules developed according to application-specific surgical tasks, emphasizing streamlined integration with intraoperative CBCT. These include multi-modality image display; 3D-3D rigid and deformable registration to bring preoperative image and planning data to the most up-to-date CBCT; 3D-2D registration of planning and image data to real-time fluoroscopy; infrared, electromagnetic, and video-based trackers used individually or in hybrid arrangements; augmented overlay of image and planning data in endoscopic or in-room video; and real-time "virtual fluoroscopy" computed from GPU-accelerated digitally reconstructed radiographs (DRRs). Application in three preclinical scenarios (temporal bone, skull base, and spine surgery) demonstrates the utility of the modular, task-specific approach in progressively complex tasks.

CONCLUSIONS

The design and development of a system architecture for image-guided surgery has been reported, demonstrating enhanced utilization of intraoperative CBCT in surgical applications with vastly different requirements. The system integrates C-arm CBCT with a broad variety of data sources in a modular fashion that streamlines the interface to application-specific tools, accommodates distinct workflow scenarios, and accelerates testing and translation of novel toolsets to clinical use. The modular architecture was shown to adapt to and satisfy the requirements of distinct surgical scenarios from a common code-base, leveraging software components arising from over a decade of effort within the imaging and computer-assisted interventions community.