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Sohrab S. Virk, Frank M. Phillips, and Safdar N. Khan


Cervical spondylotic myelopathy (CSM) is a progressive spinal condition that often requires surgery. Studies have shown the clinical equivalency of anterior versus posterior approaches for CSM surgery. The purpose of this study was to determine the amount and type of resources used for anterior and posterior surgical treatment of CSM by using large national databases of clinical and financial information from patients.


This study consists of 2 large cohorts of patients who underwent either an anterior or posterior approach for treatment of CSM. These patients were selected from the Medicare 5% National Sample Administrative Database (SAF5) and the Humana orthopedic database (HORTHO), which is a database of patients with private payer health insurance. The outcome measures were the cost of a 90-day episode of care, as well as a breakdown of the cost components for each surgical procedure between 2005 and 2014.


A total of 16,444 patients were included in this analysis. In HORTHO, there were 10,332 and 1556 patients treated with an anterior or posterior approach for CSM, respectively. In SAF5, there were 3851 and 705 patients who were treated by an anterior or posterior approach for CSM, respectively. The mean ± SD reimbursements for anterior and posterior approaches in the HORTHO database were $20,863 ± $2014 and $23,813 ± $4258, respectively (p = 0.048). The mean ± SD reimbursements for anterior and posterior approaches in the SAF5 database were $18,219 ± $1053 and $25,598 ± $1686, respectively (p < 0.0001). There were also significantly higher reimbursements for a rehabilitation/skilled nursing facility and hospital/inpatient care for patients who underwent a posterior approach in both the private payer and Medicare databases. In all cohorts in this study, the hospital-related reimbursement was more than double the surgeon-related reimbursement.


This study provides resource utilization information for a 90-day episode of care for both anterior and posterior approaches for CSM surgery. There is a statistically significant higher resource utilization for patients undergoing the posterior approach for CSM, which is consistent with the literature. Understanding the reimbursement patterns for anterior versus posterior approaches for CSM will help providers design a bundled payment for patients requiring surgery for CSM, and this study suggests that a subset of patients who require the posterior approach for treatment also require greater resources. The data also suggest that hospital-related reimbursement is the major driver of payments.

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Keith B. Quattrocchi, Phillip Kissel, William G. Ellis, and Edmund H. Frank

✓ The case of a cavernous angioma of the tentorium cerebelli is described. This is the seventh reported case of a cavernous angioma in this unusual location and the first of a dural cavernous angioma demonstrated by magnetic resonance imaging. The clinical presentation, radiographic features, and surgical treatment of these rare tumors are discussed, along with a review of the literature.

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A cadaveric precision and accuracy analysis of augmented reality–mediated percutaneous pedicle implant insertion

Presented at the 2020 AANS/CNS Joint Section on Disorders of the Spine and Peripheral Nerves

Camilo A. Molina, Frank M. Phillips, Matthew W. Colman, Wilson Z. Ray, Majid Khan, Emanuele Orru’, Kornelis Poelstra, and Larry Khoo


Augmented reality–mediated spine surgery (ARMSS) is a minimally invasive novel technology that has the potential to increase the efficiency, accuracy, and safety of conventional percutaneous pedicle screw insertion methods. Visual 3D spinal anatomical and 2D navigation images are directly projected onto the operator’s retina and superimposed over the surgical field, eliminating field of vision and attention shift to a remote display. The objective of this cadaveric study was to assess the accuracy and precision of percutaneous ARMSS pedicle implant insertion.


Instrumentation was placed in 5 cadaveric torsos via ARMSS with the xvision augmented reality head-mounted display (AR-HMD) platform at levels ranging from T5 to S1 for a total of 113 total implants (93 pedicle screws and 20 Jamshidi needles). Postprocedural CT scans were graded by two independent neuroradiologists using the Gertzbein-Robbins scale (grades A–E) for clinical accuracy. Technical precision was calculated using superimposition analysis employing the Medical Image Interaction Toolkit to yield angular trajectory (°) and linear screw tip (mm) deviation from the virtual pedicle screw position compared with the actual pedicle screw position on postprocedural CT imaging.


The overall implant insertion clinical accuracy achieved was 99.1%. Lumbosacral and thoracic clinical accuracies were 100% and 98.2%, respectively. Specifically, among all implants inserted, 112 were noted to be Gertzbein-Robbins grade A or B (99.12%), with only 1 medial Gertzbein-Robbins grade C breach (> 2-mm pedicle breach) in a thoracic pedicle at T9. Precision analysis of the inserted pedicle screws yielded a mean screw tip linear deviation of 1.98 mm (99% CI 1.74–2.22 mm) and a mean angular error of 1.29° (99% CI 1.11°–1.46°) from the projected trajectory. These data compare favorably with data from existing navigation platforms and regulatory precision requirements mandating that linear and angular deviation be less than 3 mm (p < 0.01) and 3° (p < 0.01), respectively.


Percutaneous ARMSS pedicle implant insertion is a technically feasible, accurate, and highly precise method.

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Douglas Kondziolka, Phillip V. Parry, L. Dade Lunsford, Hideyuki Kano, John C. Flickinger, Susan Rakfal, Yoshio Arai, Jay S. Loeffler, Stephen Rush, Jonathan P. S. Knisely, Jason Sheehan, William Friedman, Ahmad A. Tarhini, Lanie Francis, Frank Lieberman, Manmeet S. Ahluwalia, Mark E. Linskey, Michael McDermott, Paul Sperduto, and Roger Stupp


Estimating survival time in cancer patients is crucial for clinicians, patients, families, and payers. To provide appropriate and cost-effective care, various data sources are used to provide rational, reliable, and reproducible estimates. The accuracy of such estimates is unknown.


The authors prospectively estimated survival in 150 consecutive cancer patients (median age 62 years) with brain metastases undergoing radiosurgery. They recorded cancer type, number of brain metastases, neurological presentation, extracranial disease status, Karnofsky Performance Scale score, Recursive Partitioning Analysis class, prior whole-brain radiotherapy, and synchronous or metachronous presentation. Finally, the authors asked 18 medical, radiation, or surgical oncologists to predict survival from the time of treatment.


The actual median patient survival was 10.3 months (95% CI 6.4–14). The median physician-predicted survival was 9.7 months (neurosurgeons = 11.8 months, radiation oncologists = 11.0 months, and medical oncologist = 7.2 months). For patients who died before 10 months, both neurosurgeons and radiation oncologists generally predicted survivals that were more optimistic and medical oncologists that were less so, although no group could accurately predict survivors alive at 14 months. All physicians had individual patient survival predictions that were incorrect by as much as 12–18 months, and 14 of 18 physicians had individual predictions that were in error by more than 18 months. Of the 2700 predictions, 1226 (45%) were off by more than 6 months and 488 (18%) were off by more than 12 months.


Although crucial, predicting the survival of cancer patients is difficult. In this study all physicians were unable to accurately predict longer-term survivors. Despite valuable clinical data and predictive scoring techniques, brain and systemic management often led to patient survivals well beyond estimated survivals.