Malignant Carotid Paraganglioma: A Case Report

Carotid body tumors (CBTs) are rare neoplasms of the neuroectoderm accounting for 0.6% of head and neck tumors, with a 2%-12.5% risk of malignancy. While surgical resection has been associated with a high rate of neurologic and vascular complications, it remains the mainstay of treatment for malignant CBTs. We present the case of a 40-year-old female with a 5-year history of progressively enlarging right-sided neck mass, with MRI and MRA showing a Shamblin grade III CBT encasement of the internal carotid artery (ICA). Blood flow was absent in the petrous segment of ICA, with great collateralization of brain blood supply, enabling en bloc resection of the tumor with a carotid bulb and ligation of the common carotid artery (CCA) without vascular reconstruction. Further, we describe the characteristics and current management for malignant CBTs, including surgical management, pre-surgical embolization, and adjuvant radiation therapy.

Identification of Deep Cervical Fascial Layers During Anterior Cervical Spine Exposure

BACKGROUND

Anterior approaches to the cervical spine are among the most common exposures by which neurosurgeons and orthopedic surgeons access the prevertebral space and ultimately the cervical disk and vertebral bodies. There is a paucity of literature describing the microanatomic fascial planes of the neck with respect to anterior cervical approaches.

OBJECTIVE

To delineate the microanatomic connections of the cervical fascial planes pertinent to anterior cervical exposure.

METHODS

Using a cadaveric model, original illustrations, the Visible Human Project, and an original surgical video, we demonstrate a stepwise method for identifying the correct planes for anterior cervical exposure.

RESULTS

A step-by-step method for identifying the anterior cervical fascial planes intraoperatively is demonstrated.

CONCLUSION

A comprehensive understanding of anterior cervical microsurgical anatomy is vital for performing a methodical yet efficient approach to the prevertebral space while minimizing retraction and iatrogenic injury to the surrounding neurovascular structures.

International Learner Perceptions, Educational Value, and Cost Associated With the Use of Start-to-Finish Surgical Simulation Compared With Cadaveric Models

BACKGROUND

Graduate surgical education is highly variable across regions and institutions regarding case volume and degree of trainee participation in each case. Dedicated educational curriculum using cadaveric tissue has been shown to enhance graduate surgical training, however with associated financial and utility burden to the institution.

OBJECTIVE

To investigate the utility of educational and cost applications of a novel method of combining mixed organic hydrogel polymers and 3-dimensional printed anatomic structures to create a complete "start-to-finish" simulation for resident education in spinal anatomy, instrumentation, and surgical techniques.

METHODS

This qualitative pilot study investigated 14 international participants on achievement of objective and personal learning goals in a standardized curriculum using biomimetic simulation compared with cadaveric tissue. A questionnaire was developed to examine trainee evaluation of individual anatomic components of the biomimetic simulators compared with previous experience with cadaveric tissue.

RESULTS

A total of 210 responses were acquired from 14 participants. Six participants originated from US residency education programs and 8 from transcontinental residency programs. Survey results for the simulation session revealed high user satisfaction. Score averages for each portion of the simulation session indicated learner validation of anatomic features for the simulation compared with previous cadaveric experience. Cost analysis resulted in an estimated savings of $10 833.00 for this single simulation session compared with previous cadaveric tissue sessions.

CONCLUSION

The results of this study indicate a strong potential of establishing biomimetic simulation as a cost-effective and high-quality alternative to cadaveric tissue for the instruction of fundamental spine surgical techniques.

Revision Thoracic Syringo-Subarachnoid Shunt for Recurrent Syrinx With Syringobulbia: Technique and Surgical Video

Syringomyelia and syringobulbia continue to remain a diagnosis without widely accepted treatment paradigms. Furthermore, the currently available treatment options can be complicated by delayed symptom recurrence and the need for revision surgery. Revision intradural surgery is challenging, and currently, there is a paucity of literature describing safe techniques for revision syringotomy and shunt placement. In this technical report, we present a surgical video describing the technique of revision syringo-subarachnoid shunt placement in a 61-year-old female with a history of multiple intradural surgeries who presented with progressively symptomatic ascending syringobulbia. 

History of Bone Grafts in Spine Surgery

Bone grafting replaces damaged or missing bone with new bone and is used for surgical arthrodesis. Patients benefit from a huge variety of bone graft techniques and options for spinal fusions. This article reviews the rich history of bone grafts in surgery with particular emphasis on spinal fusion. During the early years of bone grafting in spine surgery, bone grafts were used on tuberculosis patients, and the structural support of the graft was most the important consideration. Between 1960 and 2000, many advances were made, specifically in the use of bone graft substitutes. The field of bone grafts in spine surgery has evolved rapidly since first described.

Imparting Knowledge to a Unique Generation of Budding Clinical Anatomists

The newest influx of young learners of anatomy in medical education belong to Generation Z (GenZ), a unique generation of individuals that are vastly different from the Millennial and Generation Z trainees before them. It has been shown that the first wave of GenZ members entering the workforce possess considerable talent for innovation and dedication to their work. However, recent evidence suggests that GenZ learners are also potently susceptible to environmental influences and place heavy emphasis on personal relationships developed with their instructors. This characteristic presents a challenge to current instructors of clinical anatomy participating in intergenerational teaching, especially with respect to instructing the intangible aspects of a successful academic career. This article highlights the pressing educational challenges faced by anatomy instructors and provides a concise method to reach Generation Z trainees in a way that will help prepare them for the personal and professional milestones needed to achieve a successful academic and clinical career. This article is protected by copyright. All rights reserved.

Long-term clinical outcome of minimally invasive versus open single-level transforaminal lumbar interbody fusion for degenerative lumbar diseases: a meta-analysis

BACKGROUND CONTEXT

Minimally invasive surgical transforaminal lumbar interbody fusion (MIS-TLIF) was developed in addition to open-TLIF to minimize iatrogenic soft-tissue damage. A potential disadvantage of MIS-TLIF is inadequate visualization, which may lead to incomplete neural decompression and a less robust arthrodesis. This may cause long-term problems and result in decreased patient satisfaction.

PURPOSE

To evaluate the long-term clinical outcome, measured by patient-reported outcomes (PROMs), of patients with degenerative lumbar diseases treated with single-level TLIF (open vs. minimally invasive) with a minimum follow-up of 2-years.

STUDY DESIGN

Meta-analysis.

METHODS

The systematic review was conducted according to the PRISMA guidelines. Relevant studies were identified from Pubmed, MEDLINE, EMBASE, Scopus, Web of Science, and CENTRAL from the date of inception to August 2019. The inclusion criteria were (1) longitudinal comparative studies of MIS-TLIF versus open-TLIF approach for degenerative spine disease (2) outcomes reported as PROMs, (3) minimum follow-up of 2-years.

RESULTS

Sixteen studies were included in the analysis. In total, 1,321 patients were included (660 MIS-TLIF& 661 open-TLIF). The following PROMS were analyzed: EQ-5D, SF, ODI, and VAS. Both techniques resulted in significant improvement in PROM, which remained significant at 2-years follow-up. However, no significant differences were found in all PROMs at 2-years follow-up. Both treatments resulted in a high rate of spinal fusion (80.5% vs. 91.1%; p=.29) and low rate of reoperation (3.0% vs. 2.4%; p=.50) or adjacent segment disease (12.6% vs. 12.40%; p=.50).

CONCLUSIONS

MIS-TLIF and open-TLIF have comparable long-term clinical outscomes. Both operations can significantly reduce pain and positively improve PROMs. No significant differences were found between both treatments in clinical outcomes at a follow-up of minimal 2-years. Therefore, MIS-TLIF seems to be an effective and safe alternative to traditional open-TLIF in the long-term.

Three-Dimensionally Printed Surgical Simulation Tool for Brain Mapping Training and Preoperative Planning

BACKGROUND

Brain mapping is the most reliable intraoperative tool for identifying surrounding functional cortical and subcortical brain parenchyma. Brain mapping procedures are nuanced and require a multidisciplinary team and a well-trained neurosurgeon. Current training methodology involves real-time observation and operation, without widely available surgical simulation.

OBJECTIVE

To develop a patient-specific, anatomically accurate, and electrically responsive biomimetic 3D-printed model for simulating brain mapping.

METHODS

Imaging data were converted into a 2-piece inverse 3D-rendered polyvinyl acetate shell forming an anatomically accurate brain mold. Functional and diffusion tensor imaging data were used to guide wire placement to approximate the projection fibers from the arm and leg areas in the motor homunculus. Electrical parameters were generated, and data were collected and processed to differentiate between the 2 tracts. For validation, the relationship between the electrical signal and the distance between the probe and the tract was quantified. Neurosurgeons and trainees were interviewed to assess the validity of the model.

RESULTS

Material testing of the brain component showed an elasticity modulus of 55 kPa (compared to 140 kPa of cadaveric brain), closely resembling the tactile feedback a live brain. The simulator's electrical properties approximated that of a live brain with a voltage-to-distance correlation coefficient of r2 = 0.86. Following 32 neurosurgeon interviews, ∼96% considered the model to be useful for training.

CONCLUSION

The realistic neural properties of the simulator greatly improve representation of a live surgical environment. This proof-of-concept model can be further developed to contain more complicated tractography, blood and cerebrospinal fluid circulation, and more in-depth feedback mechanisms.

Establishing a Cost-Effective 3-Dimensional Printing Laboratory for Anatomical Modeling and Simulation: An Institutional Experience

SUMMARY STATEMENT

Three-dimensional (3D) printing is rapidly growing in popularity for anatomical modeling and simulation for medical organizations across the world. Although this technology provides a powerful means of creating accurately representative models of anatomic structures, there remains formidable financial and workforce barriers to understanding the fundamentals of technology use, as well as establishing a cost- and time-effective system for standardized incorporation into a workflow for simulator design and anatomical modeling. There are many factors to consider when choosing the appropriate printer and accompanying software to succeed in accomplishing the desired goals of the executing team. The authors have successfully used open-access software and desktop fused deposition modeling 3D printing methods to produce more than 1000 models for anatomical modeling and procedural simulation in a cost-effective manner. It is our aim to share our experience and thought processes of implementing 3D printing into our anatomical modeling and simulation workflow to encourage other institutions to comfortably adopt this technology into their daily routines.

Arachnoid Web Fenestration: Diagnostic and Surgical Nuances

Arachnoid web (AW) is a rare phenomenon that has only been described in small case reports and case series,¹ most commonly presenting with upper motor neuron signs and subtle radiographic findings, such as the classically described "scalpel sign."² In this report, we demonstrate the use of imaging and operative techniques that have not been previously shown in the literature as a video for AW. These include high-definition magnetic resonance imaging (MRI) sequences for preoperative diagnosis, use of intraoperative ultrasonography for identification of adhesions, and operative technique for AW fenestration (Video 1). The patient consented to this manuscript. A 64-year-old female patient developed progressive difficulty with balance and ambulation that particularly worsened over the last 4 months associated with tingling and numbness in the bilateral lower extremities. Physical examination revealed spastic gait and upper motor neuron signs in the lower extremities along with left foot drop. MRI revealed a chronic noncontrast-enhancing intramedullary lesion, along with a spinal cord indentation at the level T6 with an associated fiber between the cord and the posterior dura. Surgical intervention was performed with the use of intraoperative fluoroscopy and ultrasound for real-time identification of the surgical site and the AW. Under the microscope, the dura was incised while preserving the arachnoid. The AW was carefully dissected, leaving the portions that were tethered onto the cord. Two weeks postoperatively, the patient's gait was markedly improved, with resolved neurologic function in the lower extremities. Follow-up MRI at 3 months demonstrated resolved medullary syrinx and normalization of the spinal cord contour.

Neurosurgical Interactive Teaching Series: Multidisciplinary Educational Approach

OBJECTIVE

The goal of this manuscript is to investigate the effects of a multidisciplinary multinational web-based teaching conference on trainee education, research, and patient care.

METHODS

We present the structure, case selection, and presentation of our educational lectures. We retrospectively reviewed our database to gather data on the number of presentations, type of presentation, and the pathology diagnosis from November 11, 2016 until February 28, 2020. To investigate attendee satisfaction, we analyzed our yearly continuing medical education evaluation survey results to report the impact that this series may have had on our attendees. We assigned a numeric value to the answers, and the mean overall scores were compared through an analysis of variance. Further analysis on specific questions was performed with a Fisher exact test.

RESULTS

We have hosted 150 lectures, in which we have presented 208 neurosurgical cases corresponding to 133 general session, 59 pituitary, and 16 spine cases, as well as 28 distinct lectures by guest speakers from institutions across the globe. We received 61 responses to our yearly continuing medical education evaluations over the course of 3 years. On these evaluations, we have maintained an excellent overall rating from 2017-2019 (two-sided P > 0.05) and received significantly less suggestions to improve the series comparing 2017 with 2019 (two-sided, P= 0.04).

CONCLUSIONS

As the world of medicine is constantly changing, we are in need of developing new tools to enhance our ability to relay knowledge through accredited and validated methods onto physicians in training, such as the implementation of structured, multidisciplinary, case-based lectures as presented in this manuscript.

Does Thoracic Manipulation Cause Extravasation at Joint Following Facet Injections?

Facet injections and other pain management interventions are commonly performed in combination with conservative therapy to address spinal pain. Joint mobilizations are a highly utilized intervention for manual practitioners to treat patients with spinal pain. Clinical reasoning and decision making models have not been well described in the literature assessing if and when joint mobilizations are appropriate interventions immediately or shortly following facet injection procedures. It has not been well studied if joint mobilizations immediately following facet injections negatively impact the injected solution at the respective joint and thus influence therapeutic effect. More specifically, there is a paucity of evidence assessing this at the thoracic spine. The purpose of this study was to assess if thoracic joint high-velocity low amplitude thrust manipulations caused extravasation of injected radiolucent material at respective thoracic facet joints on a cadaver. This study included an expert physician performing ultrasound-guided facet injections, an experienced manual physical therapist performing joint mobilization techniques, and fluoroscopic assessment of radiolucent material pre- and post-manipulation by a board-certified radiologist with experience in this field of study. Imaging interpretation confirmed that extravasation at respective joints did not occur following manipulation. This basic research can help guide clinical reasoning for practitioners considering implementing manual therapy techniques following facet injections and help guide further research. 

3-Dimensionally Printed Biomimetic Surgical Simulation-Operative Technique of a Transforaminal Lumbar Interbody Fusion: 2-Dimensional Operative Video

We present a surgical video highlighting the technical demonstration and microsurgical anatomy of an L4-5 transforaminal lumbar interbody fusion utilizing a combination of thermoplastic polymers and 3-dimensional printing technology to create a biomimetic lumbar spine surgical simulator. The posterior elements of L4-5 and the inferior portion of L3 are exposed in their entirety, including the transverse processes in order to identify the appropriate landmarks for pedicle screw insertion. The interspinous ligament of L4-5 is removed, and an interlaminar spreader is used to distract the facet joint. An inferior L4 facetectomy is performed for local autograft harvesting. The L4 and L5 pedicles are skeletonized to completely open the foramen in order to ensure that the exiting nerve root will not be compromised during cage insertion. The ligamentum flavum is then removed, exposing the common thecal sac and L5 traversing root. The L4 exiting nerve root is then identified, completing Kambin's triangle and location of the disc space. The disc is incised, and a combination of punches and curettes are used to completely remove the disc. After an interbody trial is used to assess the proper cage size, the cage is packed with graft and inserted into the midline of the disc space. Pedicle screws are then placed using an anatomic freehand technique, and intraoperative fluoroscopy is performed in order to evaluate the instrumentation and interbody position. If a contralateral decompression is required, a facet-sparing technique is performed in order to preserve bony surface for the fusion. Patient consent was not required for this simulation video.

Investigation of the "Superior Facet Rule" Using 3D-Printed Thoracic Vertebrae With Simulated Corticocancellous Interface

BACKGROUND

Pedicle screw placement is the most common method of fixation in the thoracic spine. Use of the "superior facet rule" allows the operator to locate the borders of the pedicle reliably using posterior landmarks alone. This study investigated the ability of 3-dimensionally (3D)-printed thoracic vertebrae, made from combined thermoplastic polymers, to demonstrate pedicle screw cannulation accurately using the superior facet as a reliable landmark.

METHODS

An anonymized computed tomography scan of the thoracic spine was obtained. The T1-T12 thoracic vertebrae were anatomically segmented and 3D-printed. The pedicle diameters and distance from the midpoint of the superior facet to the ventral lamina were recorded. A total of 120 thoracic pedicles in 60 thoracic vertebral models were instrumented using a freehand technique based only on posterior landmarks. The vertebral models were then coronally cut and examined for medial or lateral violations of the pedicle after screw placement.

RESULTS

A total of 120 pedicle screws were placed successfully within the 3D-printed thoracic vertebral models. Average measurements fell within 1 standard deviation of previous population studies. There were no pedicle wall violations using standard posterior element landmarks for instrumentation. There were 3 lateral violations of the vertebral body wall during screw placement, all attributable to the insertion technique.

CONCLUSIONS

3D-printed thoracic vertebral models using combined thermoplastic polymers can accurately demonstrate the anatomical ultrastructure and posterior element relationships of the superior facet rule for safe thoracic pedicle screw placement. This method of vertebral model prototyping could prove useful for surgical education and demonstrating spinal anatomy.

Techniques and Tips for Freehand Placement of C7 Pedicle Screws With Respect to Cervicothoracic Constructs: 2-Dimensional Operative Video

We present a surgical video highlighting the technical pearls for C7 pedicle screw placement with respect to cervicothoracic constructs. Pedicle screw placement into C7 has been shown to enhance the biomechanical stability of both cervical and cervicothoracic constructs and is safe for patient related outcomes.1,2 Rod placement across the cervicothoracic junction is known to be difficult because of the variable starting point of the C7 pedicle screw, which may cause misalignment of the polyaxial heads with respect to the C7 and C6 screw heads. Using our step-wise method of anatomic screw placement, this potential pitfall is minimized. The T1 pedicle screw is placed first. The C6 lateral mass screw starting point is displaced slightly superiorly from the midpoint of the lateral mass in order to make room for the polyaxial head of the C7 pedicle screw. A small laminotomy is performed in order to find the medial border of the C7 pedicle. Palpation of the medial border allows for an approximation of the pedicle limits. The cranial-caudal angle of drilling is perpendicular to the C7 superior facet, and the medial-lateral trajectory typically falls between 15 and 20 degrees medial. Once the pedicle is cannulated, a ball-tipped probe is used to confirm intraosseous position. A rod is cut and contoured to the appropriate length of the construct. The C7 pedicle screw should capture the rod easily with slight displacement of the polyaxial head. Postinstrumentation anteroposterior and lateral fluoroscopy are performed to confirm good position of the lateral mass and pedicle screws. Patient consent was not required for this cadaveric surgical video.

Operative Adjuncts and Technique for En Bloc Removal of Lumbar Intradural-Extramedullary Tumor: 2-Dimensional Operative Video

We present a surgical video illustrating the technique for en bloc resection of an intradural-extramedullary lumbar tumor. The patient is a 63-yr-old woman presenting with worsening bilateral leg pain. Imaging of her lumbar spine showed an enhancing, circumscribed intradural-extramedullary tumor compressing her cauda equina at the L2 level. With informed patient consent, an L1-L3 laminectomy was performed, and intraoperative ultrasound provided the tumor location in order to plan the dural opening as well as define the tumor boundaries with respect to the surrounding nerve roots. The nerve roots were found to be dorsal to the tumor on the ultrasound and appeared to be separate from the tumor capsule. After the dura was opened, the nerve roots were dissected from the tumor capsule and the filum was identified at its proximal and distal portions relative to the mass. The tumor appeared to be arising from the filum itself. Intraoperative electromyography monitoring and stimulation identified the motor roots around the filum and were dissected away. The filum was isolated and cut proximally in order to prevent upward displacement of the mass above the dural opening. The distal portion was then cut and the tumor was removed en bloc. The patient had good postoperative relief of her leg pain and no new neurologic or genitourinary complications. This case highlights the preoperative and intraoperative surgical planning as well as detailed technical aspects of en bloc intradural-extramedullary lumbar tumor resection with preservation of the tumor capsule in order to achieve gross total resection.

Considerations and Cautions for Three-Dimensional-Printed Personal Protective Equipment in the COVID-19 Crisis

The recent decline in available personal protective equipment (PPE) due to the novel coronavirus (COVID-19) pandemic has given rise to a host of three-dimensional (3D) printed prototypes for facemask and respirator units. Many of these models have been made open access and publicly available for printing and use, and have been promoted by various media outlets. Although these desktop 3D printing measures have provided a possible venue for success in providing homemade and cost-effective PPE to health care workers, the rapid dissemination of these prototypes has been performed without reproducible methods of standardization and vetted safety in use. Although these methods have not been sanctioned by authoritative organizations as viable production approaches to address the PPE shortage, a concerted effort within the 3D printing community to adhere to scientific methodology and organized research efforts has the potential to provide a solution to this critical issue.

Cost-Effective Method for 3-Dimensional Printing Dynamic Multiobject and Patient-Specific Brain Tumor Models: Technical Note

BACKGROUND

Three-dimensional (3D) printing is a powerful tool for replicating patient-specific anatomic features for education and surgical planning. The advent of "desktop" 3D printing has created a cost-effective and widely available means for institutions with limited resources to implement a 3D-printing workflow into their clinical applications. The ability to physically manipulate the desired components of a "dynamic" 3D-printed model provides an additional dimension of anatomic understanding. There is currently a gap in the literature describing a cost-effective and time-efficient means of creating dynamic brain tumor 3D-printed models.

METHODS

Using free, open-access software (3D Slicer) for patient imaging to Standard Tessellation Language file conversion, as well as open access Standard Tessellation Language editing software (Meshmixer), both intraaxial and extraaxial brain tumor models of patient-specific pathology are created.

RESULTS

A step-by-step methodology and demonstration of the software manipulation techniques required for creating cost-effective, multidimensional brain tumor models for patient education and surgical planning are exhibited using a detailed written guide, images, and a video display.

CONCLUSIONS

In this technical note, we describe in detail the specific functions of free, open-access software and desktop 3D printing techniques to create dynamic and patient-specific brain tumor models for education and surgical planning.

Investigation of a three-dimensional printed dynamic cervical spine model for anatomy and physiology education

INTRODUCTION

Three-dimensional (3D) printing of anatomical structures is a growing method of education for students and medical trainees. These models are generally produced as static representations of gross surface anatomy. In order to create a model that provides educators with a tool for demonstration of kinematic and physiologic concepts in addition to surface anatomy, a high-resolution segmentation and 3D-printingtechnique was investigated for the creation of a dynamic educational model.

METHODS

An anonymized computed tomography scan of the cervical spine with a diagnosis of ossification of the posterior longitudinal ligament was acquired. Using a high-resolution thresholding technique, the individual facet and intervertebral spaces were separated, and models of the C3-7 vertebrae were 3D-printed. The models were placed on a myelography simulator and subjected to flexion and extension under fluoroscopy, and measurements of the spinal canal diameter were recorded and compared to in-vivo measurements. The flexible 3D-printed model was then compared to a static 3D-printed model to determine the educational benefit of demonstrating physiologic concepts.

RESULTS

The canal diameter changes on the flexible 3D-printed model accurately reflected in-vivo measurements during dynamic positioning. The flexible model also was also more successful in teaching the physiologic concepts of spinal canal changes during flexion and extension than the static 3D-printed model to a cohort of learners.

CONCLUSIONS

Dynamic 3D-printed models can provide educators with a cost-effective and novel educational tool for not just instruction of surface anatomy, but also physiologic concepts through 3D ex-vivo modeling of case-specific physiologic and pathologic conditions.

The SpineBox: A Freely Available, Open-access, 3D-printed Simulator Design for Lumbar Pedicle Screw Placement

Background

The recent COVID-19 pandemic has demonstrated the need for innovation in cost-effective and easily produced surgical simulations for trainee education that are not limited by physical confines of location. This can be accomplished with the use of desktop three-dimensional (3D) printing technology. This study describes the creation of a low-cost and open-access simulation for anatomical learning and pedicle screw placement in the lumbar spine, which is termed the SpineBox.

Materials and methods

An anonymized CT scan of the lumbar spine was obtained and converted into 3D software files of the L1-L5 vertebral bodies. A computer-assisted design (CAD) software was used to assemble the vertebral models into a simulator unit in anatomical order to produce an easily prototyped simulator. The printed simulator was layered with foam in order to replicate soft tissue structures. The models were instrumented with pedicle screws using standard operative technique and examined under fluoroscopy.

Results

Ten SpineBoxes were created using a single desktop 3D printer, with accurate replication of the cortico-cancellous interface using previously validated techniques. The models were able to be instrumented with pedicle screws successfully and demonstrated quality representation of bony structures under fluoroscopy. The total cost of model production was under $10.

Conclusion

The SpineBox represents the first open-access simulator for the instruction of spinal anatomy and pedicle screw placement. This study aims to provide institutions across the world with an economical and feasible means of spine surgical simulation for neurosurgical trainees and to encourage other rapid prototyping laboratories to investigate innovative means of creating educational surgical platforms in the modern era.

Microanatomical considerations for safe uncinate removal during anterior cervical discectomy and fusion: 10-year experience

Cervical radiculopathy from uncovertebral joint (UVJ) hypertrophy and nerve root compression often occurs anterior and lateral within the cervical intervertebral foramen, presenting a challenge for complete decompression through anterior cervical approaches owing to the intimate association with the vertebral artery and associated venous plexus. Complete uncinatectomy during anterior cervical discectomy and fusion (ACDF) is a controversial topic, many surgeons relying on indirect nerve root decompression from restoration of disc space height. However, in cases of severe UVJ hypertrophy, indirect decompression does not adequately address the underlying pathophysiology of anterolateral foraminal stenosis. Previous reports in the literature have described techniques involving extensive dissection of the cervical transverse process and lateral uncinate process (UP) in order to identify the vertebral artery for safe removal of the UP. Recent anatomical investigations have detailed the microanatomical organization of the fibroligamentous complex surrounding the UP and neurovascular structures. The use of the natural planes formed from the encapsulation of these connective tissue layers provides a safe passage for lateral UP dissection during anterior cervical approaches. This can be performed from within the disc space during ACDF to avoid extensive lateral dissection. In this article, we present our 10-year experience using an anatomy-based microsurgical technique for safe and complete removal of the UP during ACDF for cervical radiculopathy caused by UVJ hypertrophy.

Total Anterior Uncinatectomy During Anterior Discectomy and Fusion for Recurrent Cervical Radiculopathy: A Two-dimensional Operative Video and Technical Report

A common cause of cervical radiculopathy from degenerative foraminal stenosis is severe uncovertebral hypertrophy. It is difficult to accomplish complete foraminal decompression in these cases with posterior techniques without the removal of a large portion of the facet joint. Total removal of the uncovertebral joint from an anterior approach allows for complete decompression of the exiting cervical nerve root and has been shown to be a safe technique. In this surgical video and technical report, we demonstrate the surgical anatomy and operative technique of a two-level anterior uncinatectomy during anterior discectomy and fusion (ACDF) for recurrent cervical radiculopathy after a previous multi-level posterior foraminotomy. The patient is a 67-year-old male with a progressive left arm and neck pain with radiographic, clinical, and electrophysiologic diagnostic evidence of active C6 and C7 radiculopathies from degenerative foraminal stenosis at the C5-6 and C6-7 levels. Posterior foraminotomies had been performed without significant improvement in his radicular pain. A repeat MRI demonstrated lateral foraminal stenosis from severe uncovertebral joint hypertrophy at the C5-6 and C6-7 levels. After acquiring informed consent from the patient, an anterior approach was performed with complete removal of the uncovertebral joints at both levels with discectomy and fusion. Postoperatively, the patient had complete resolution of his radicular pain and remained pain-free at the latest follow-up. Complete uncinatectomy and ACDF is an effective technique for complete foraminal decompression in cases of refractory radiculopathy and neck pain after unsuccessful posterior decompression.

Vertebral Artery Injury with Coinciding Unstable Cervical Spine Trauma: Mechanisms, Evidence-based Management, and Treatment Options

Unstable traumatic cervical spine fracture is a commonly encountered neurosurgical issue. Concomitant vertebral artery injuries present a challenge in surgical decision-making regarding the timing and order of surgical intervention with respect to endovascular intervention and internal fixation of the unstable fracture. Currently, there are no studies that have specifically examined stroke rate or outcomes for patients who have vertebral artery injuries and unstable cervical spine fractures with respect to temporal treatment course. The purpose of this paper is to review the current evidence for the standards of diagnosis and management of vertebral artery injuries with coinciding unstable cervical spine injuries and propose an evidence-based algorithm for workup and treatment.

Orientation Planning in the Fused Deposition Modeling 3D Printing of Anatomical Spine Models

Three‐dimensional (3D) printing has revolutionized medical training and patient care. Clinically it is used for patient‐specific anatomical modeling with respect to surgical procedures. 3D printing is heavily implemented for simulation to provide a useful tool for anatomical knowledge and surgical techniques. Fused deposition modeling (FDM) is a commonly utilized method of 3D printing anatomical models due to its cost-effectiveness. A potential disadvantage of FDM 3D printing complex anatomical shapes is the limitations of the modeling system in providing accurate representations of multifaceted ultrastructure, such as the facets of the lumbar spine. In order to utilize FDM 3D printing methods in an efficient manner, the pre-printing G-code assembly must be oriented according to the anatomical nature of the print. This article describes the approach that our institution's 3D printing laboratory has used to manipulate models’ printing angles in regard to the print bed and nozzle, according to anatomical properties, thus creating quality and cost-effective anatomical spine models for education and procedural simulation. 

The pterygospinous and pterygoalar ligaments and their relationship to the mandibular nerve: Application to a better understanding of various forms of trigeminal neuralgia

INTRODUCTION

Ossification of the pterygospinous and pterygoalar ligaments has been well documented forming pterygospinous and pterygoalar bars. However, the actual ligaments have been rarely shown in the existing literature. Therefore, this study aimed to reveal the anatomy of the pterygoalar ligament/bar and pterygospinous ligament/bar, and its relationship with the branches of the mandibular nerve.

METHODS

Thirty sides from fifteen Caucasian fresh frozen cadaveric heads were used in this study. The branches of the mandibular nerve and any ligaments or bony bridges between the lateral plate of the pterygoid process and spine of the sphenoid were observed.

RESULTS

A pterygospinous ligament/bar and pterygoalar ligament/bar were defined based on the relationship with the branches of the mandibular nerve. The pterygoalar ligament/bar was further classified into two types. Twenty-seven sides (90%) had at least one pterygoalar ligament/bar or pterygospinous ligament/bar. A pterygospinous ligament/bar was found on 15 sides (50.0%). A pterygoalar ligament/bar was found on 16 sides (53.3%), and a type I on 11 sides and type II on 5 sides.

CONCLUSIONS

This finding and classification are simple to understand and easy to apply for future studies, and have important implications regarding the clinical anatomy of trigeminal neuralgia and facial pain.

Construction of an Affordable Lumbar Neuraxial Block Model Using 3D Printed Materials

Access to affordable 3D printing technology has resulted in increased interest in the creation of medical phantom task trainers. Recent research has validated the use of these trainers in simulation education. However, task trainers remain expensive, limiting their availability to medical training programs. We describe the construction of a low-cost task trainer using fused filament fabrication (FFF) printed spinal vertebrae placed in a synthetic gelatin matrix. Additionally, our model contains a realistic simulated ligamentum flavum, a removable silicone skin, as well as spinal fluid reservoir that provides a positive endpoint for intrathecal blocks. The total cost of this model was less than $400 USD. The time to 3D print the bony anatomic parts was approximately 26 hours. While we have not formally validated our model, initial impressions of tactile feel and realism were deemed positive by experienced anesthesia providers. Future work will focus on continued refinement of the model features and construction.

The importance of teaching clinical anatomy in surgical skills education: Spare the patient, use a sim!

Anatomical knowledge is a key tenet in graduate medical and surgical education. Classically, these principles are taught in the operating room during live surgical experience. This puts both the learner and the patient at a disadvantage due to environment, time, and safety constraints. Educational adjuncts such as cadaveric courses and surgical skills didactics have been shown to improve resident confidence and proficiency in both anatomical knowledge and surgical techniques. However, the cost-effectiveness of these courses is a limiting factor and in many cases prevents implementation within institutional training programs. Anatomical simulation in the form of "desktop" three-dimensional (3D) printing provides a cost-effective adjunct while maintaining educational value. This article describes the anatomical and patient-centered approach that led to the establishment of our institution's 3D printing laboratory for anatomical and procedural education. Clin. Anat. 32:124-127, 2019. © 2019 Wiley Periodicals, Inc.

Cervicothoracic Manipulation Techniques Reviewed Utilizing Three-Dimensional Spine Model

Currently, there is a paucity of studies that describe prone cervicothoracic joint high-velocity low-amplitude (HVLA) thrust techniques using an anatomically accurate, biomimetic three-dimensional (3D) spine model for educational demonstration. The purpose of this technical report was to present a learning model for two prone cervicothoracic HVLA thrust techniques using a 3D model, review intersegmental mobility observed on a 3D spine model with application of the techniques, and lastly discuss potential applications of this learning model.

How I do it: total uncinatectomy during anterior diskectomy and fusion for cervical radiculopathy caused by uncovertebral joint hypertrophy

BACKGROUND

Cervical radiculopathy from uncovertebral joint hypertrophy and foraminal stenosis is a common indication for anterior cervical diskectomy and fusion (ACDF). Often, the uncinate hypertrophy extends lateral to the foramen and impinges on the nerve close to the vertebral artery as it travels in between the transverse foramina.

METHOD

Using an injected cadaveric specimen to highlight the vital neurovascular and bony structures pertinent to this procedure, we demonstrate the technical details of complete uncinatectomy for cervical foraminal stenosis.

CONCLUSION

Total uncinatectomy is a useful adjunct during ACDF for complete foraminal decompression in cases of uncovertebral joint hypertrophy.

Freehand C2 Laminar Screw Placement: Technical Note and Operative Video

The placement of C2 laminar screws is a safe and useful method of axis fixation. The freehand method of screw placement was originally described by Wright et al., and requires detailed knowledge of the C2 posterior element anatomy, relationship to vital neurovascular structures, and technical acumen. The current evidence, surgical anatomy and technical details of screw insertion are investigated and highlighted in this manuscript and surgical video.

Use of Handheld Video Otoscopy for the Diagnosis of Acute Otitis Media: Technical Note

Otoscopy is a simple, yet fundamental tool for medical practitioners of all levels to diagnose common otologic conditions. Otoscopy is traditionally performed by a handheld light with a lens. This technique has several disadvantages, especially during teaching sessions since only a first-person view is available. Video otoscopy has the ability to project the view of the scope onto a screen that can be displayed for medical or patient education. Recently, handheld video otoscopy has advanced to display compatibility with personal devices such as cell phones or tablets. In this technical report, we demonstrate components, setup, and use of video otoscopy for otologic examination that can be easily used on a personal electronic device.

Safety and Accuracy of the Freehand Placement of C7 Pedicle Screws in Cervical and Cervicothoracic Constructs

Background: Cervical pedicle screws are advantageous in their biomechanical stability within cervical and cervicothoracic constructs. The seventh cervical vertebra contains relatively large pedicles and has a low incidence of vertebral artery localization within the transverse foramina. The freehand technique of pedicle screw insertion is advantageous in decreasing intraoperative radiation exposure both to the patient and surgeon. In this study, we investigated the safety and accuracy of C7 pedicle screw placement at our institution utilizing an anatomic freehand technique.

Methods and Materials: A retrospective study was performed, and 20 patients were identified who met the inclusion criteria over a five-year period (2013-2018). The C7 pedicle screw placement capability and accuracy were recorded. Accuracy was graded based upon postoperative imaging on a Grade 0-3 scale for breach assessment. Any neurologic complications related to screw placement were also recorded.

Results: Successful pedicle screw placement occurred in 90% of attempts (36/40). The overall screw accuracy rate was 89% (32/36). There were four minor breaches (Grade 1) identified on CT, without neurologic complications. The fusion rate in our cohort for patients with follow up greater than eight months was 100%.

Conclusions: In our patient series, the freehand technique of C7 pedicle screw placement utilizing a small laminotomy with direct pedicle palpation appears to be a safe and accurate method for screw placement, and provides adequate biomechanical stability for cervical and cervicothoracic construct fusion.

Investigation of a Cost-effective and Durable Material for Containing Ballistic Gel in the Construction of Ultrasound Phantoms

There is significant variability in the realism, cost, and structural integrity of sonographic simulators available for use currently. A common material that is used for the production of sonographic simulators is synthetic ballistic gelatin, which requires a high melting temperature for molding. In this experiment, we investigated the structural integrity of high-density polyethylene (HDPE) when exposed to melted ballistics gel for the assimilation of a sonographic lumbar puncture simulator.

3-Dimensional Simulation Videography for Instructional Placement of Bedside External Ventricular Drains

We present a narrated video simulation (Video 1) using 3-dimensional anatomic software demonstrating the proper landmarks and relevant neuroanatomy for successful bedside external ventricular drain placement. External ventricular drains are commonly inserted at the bedside for emergent intracranial pressure monitoring and/or treatment of elevated intracranial pressure by cerebrospinal fluid drainage.¹ Often, neurosurgical trainees perform this procedure early in their residency years.^2,3 The relationship of the ventricle to the external skull landmarks may be a difficult concept to grasp for junior trainees who have had limited procedural experience. Multiple catheter passes in attempt to cannulate the ventricle are associated with increased procedural risk to the patient.^2,4 Two common catheter misplacement locations leading to multiple catheter passes are lateral to the ventricle and anterior to the ventricle. In this video we highlight the relationship of the borders of the lateral ventricle to the insertion point at the skull during catheter placement. By using this resource for resident education, patient safety factors and resident procedural competence may be enhanced.

Does Surgical Intervention Help with Neurological Recovery in a Lumbar Spinal Gun Shot Wound? A Case Report and Literature Review

The third leading cause of spinal injuries are gunshot wounds to the spine, accounting for 15.2% of all spinal cord injuries. Treatment for gunshot wound spinal cord injuries (GSWSCI) remains variable, with indications for surgery being controversial. There is no clear evidence or guidelines that can help spine surgeons decide and direct surgical intervention. With the paucity of available literature, we report an interesting case of a gunshot injury to the lumbar spine at L1-L2, discuss the presentation and outcome, and evaluate relevant literature. A 27-year-old incarcerated male patient presented with a conus cauda equina asymmetrical injury involving the lower extremities and required initial medical stabilization in the intensive care unit (ICU). He subsequently underwent delayed surgical treatment with decompression and fragment resection at L1-L2. The patient improved neurologically to the American Spinal Injury Association (ASIA) Classification D and eventually regained nearly all lower extremity neurological function. Despite considerable evidence favoring the conservative management of GSWSCI and the absence of guidelines or recommendations on surgical interventions, our case report demonstrates that surgical intervention in appropriately selected patients can yield good recovery of neurological function and improvement in the quality of life. The key remains careful patient selection, the appropriate location of the retained fragment, and the extent of neurological injury that occurred. We feel surgical decompression and fragment removal, along with debridement, can result in good neurological recovery and long-term outcomes.

The Eye of Horus: The Connection Between Art, Medicine, and Mythology in Ancient Egypt

Ancient Egyptian civilization is one of the oldest cultures in human history. Ancient Egyptians are well-known for pioneering the fields of art, medicine, and the documentation of discoveries as mythological tales. The Egyptians mastered the integration of anatomy and mythology into artistic symbols and figures. The mythology of Isis, Osiris, and Horus is arguably one of the most recognized mythologies in ancient Egypt. The Eye of Horus was used as a sign of prosperity and protection, derived from the myth of Isis and Osiris. This symbol has an astonishing connection between neuroanatomical structure and function. Artistically, the Eye is comprised of six different parts. From the mythological standpoint, each part of the Eye is considered to be an individual symbol. Additionally, parts of the Eye represent terms in the series 1/2, 1/4, 1/8, 1/16, and 1/32; when this image is superimposed upon a sagittal image of the human brain, it appears that each part corresponds to the anatomic location of a particular human sensorium. In this manuscript, we highlight the possible scientific speculation of the ingenuity of ancient Egyptians’ remarkable insight into human anatomy and physiology.

The Future of Biomechanical Spine Research: Conception and Design of a Dynamic 3D Printed Cervical Myelography Phantom

Background

Three-dimensional (3D) printing is a growing practice in the medical community for patient care and trainee education as well as production of equipment and devices. The development of functional models to replicate physiologic systems of human tissue has also been explored, although to a lesser degree. Specifically, the design of 3D printed phantoms that possess comparable biomechanical properties to human cervical vertebrae is an underdeveloped area of spine research. In order to investigate the functional uses of cervical 3D printed models for replicating the complex physiologic and biomechanical properties of the human subaxial cervical spine, our institution has created a prototype that accurately reflects these properties and provides a novel method of assessing spinal canal dimensions using simulated myelography. To our knowledge, this is the first 3D printed phantom created to study these parameters.

Materials and methods

A de-identified cervical spine computed tomography imaging file was segmented using threshold modulation in 3D Slicer software. The subaxial vertebrae (C3-C7) of the scan were individualized by separating the facet joint spaces and uncovertebral joints within the software in order to create individual stereolithography (STL) files. Each individual vertebra was printed on an Ultimaker S5 dual-extrusion printer using white “tough” polylactic acid filament. A human cadaveric subaxial cervical spine was harvested to provide a control for our experiment. Both models were assessed and compared in flexion and extension dynamic motion grossly and fluoroscopically. The maximum angles of deformation on X-ray imaging were recorded using DICOM (Digital Imaging and Communications in Medicine) viewing software. In order to compare the ability to assess canal dimensions of the models using fluoroscopic imaging, a myelography simulation was designed.

Results

The cervical phantom demonstrated excellent ability to resist deformation in flexion and extension positions, attributed to the high quality of initial segmentation. The gross and fluoroscopic dynamic movement of the phantom was analogous to the cadaver model. The myelography simulator adequately demonstrated the canal dimensions in static and dynamic positions for both models. Pertinent anatomic landmarks were able to be effectively visualized for assessment of canal measurements for sagittal and transverse dimensions.

Conclusions

By utilizing the latest technologies in DICOM segmentation and 3D printing, our institution has created the first cervical myelography phantom for biomechanical evaluation and trainee instruction. By combining new technologies with anatomical knowledge, quality 3D printing shows great promise in becoming a standard player in the future of spinal biomechanical research.