Fred G. Barker II
Corinna C. Zygourakis, Kevin S. Cahill and Mark R. Proctor
A previously healthy 2-year-old girl sustained a C1–2 ligamentous injury after a motor vehicle accident and underwent successful halo immobilization, with postimmobilization images showing good cervical alignment. At the time, plain radiography, CT scanning, and MR imaging showed a normal odontoid. Four years later, however, the patient was found to have an os odontoideum, evident on plain radiography and CT imaging. At the 10-year follow-up, the os odontoideum had not been surgically repaired, and the child had mild hypermobility.
This is the first documented case in the modern imaging era of delayed os odontoideum formation after definitive CT scanning showed no fracture. As such, this suggests that os odontoideum may result from traumatic vascular interruption in the developing spine, with resulting osseous remodeling leading to an os odontoideum. This case argues against the congenital etiology of os odontoideum, as well as the strict posttraumatic theory whereby a trauma-induced odontoid fracture leads to osseous remodeling and subsequent development of an os odontoideum.
Michael M. Safaee, Cecilia L. Dalle Ore, Corinna C. Zygourakis, Vedat Deviren and Christopher P. Ames
Bone morphogenetic protein (BMP) is associated with reduced rates of pseudarthrosis and has the potential to decrease the need for revision surgery. There are limited data evaluating the cost-benefit of BMP for pseudarthrosis-related prevention surgery in adult spinal deformity.
The authors performed a single-center retrospective review of 200 consecutive patients with adult spinal deformity. Demographic data and costs of BMP, primary surgery, and revision surgery for pseudarthrosis were collected. Patients with less than 12 months of follow-up or with infection, tumor, or neuromuscular disease were excluded.
One hundred fifty-one patients (107 [71%] women) with a mean age of 65 years met the inclusion criteria. The mean number of levels fused was 10; BMP was used in 98 cases (65%), and the mean follow-up was 23 months. Fifteen patients (10%) underwent surgical revision for pseudarthrosis; BMP use was associated with an 11% absolute risk reduction in the rate of reoperation (17% vs 6%, p = 0.033), with a number needed to treat of 9.2. There were no significant differences in age, sex, upper instrumented vertebra, or number of levels fused in patients who received BMP. In a multivariate model including age, sex, number of levels fused, and the upper instrumented vertebra, only BMP (OR 0.250, 95% CI 0.078–0.797; p = 0.019) was associated with revision surgery for pseudarthrosis. The mean direct cost of primary surgery was $87,653 ± $19,879, and the mean direct cost of BMP was $10,444 ± $4607. The mean direct cost of revision surgery was $52,153 ± $26,985. The authors independently varied the efficacy of BMP, cost of BMP, and cost of reoperation by ± 50%; only reductions in the cost of BMP resulted in a cost savings per 100 patients. Using these data, the authors estimated a price point of $5663 in order for BMP to be cost-neutral.
Use of BMP was associated with a significant reduction in the rates of revision surgery for pseudarthrosis. At its current price, the direct in-hospital costs for BMP exceed the costs associated with revision surgery; however, this likely underestimates the true value of BMP when considering the savings associated with reductions in rehabilitation, therapy, medication, and additional outpatient costs.
Corinna C. Zygourakis, Ethan Winkler, Lawrence Pitts, Lisa Hannegan, Benjamin Franc and Michael T. Lawton
Postoperative head CT scanning is performed routinely at the authors' institution on all neurosurgical patients after elective aneurysm clippings. The goal of this study was to determine how often these scans influence medical management and to quantify the associated imaging costs.
The authors reviewed the medical records and accounting database of 304 patients who underwent elective (i.e., nonruptured) aneurysm clipping performed by 1 surgeon (M.T.L.) from 2010 to 2014 at the University of California, San Francisco. Specifically, the total number of postoperative head CT scans, radiographic findings, and the effect of these studies on patient management were determined. The authors obtained the total hospital costs for these patients, including the cost of imaging studies, from the hospital accounting database.
Overall, postoperative CT findings influenced clinical management in 3.6% of cases; specifically, they led to permissive hypertension in 4 patients for possible ischemia, administration of mannitol for edema and high-flow oxygen for pneumocephalus in 2 patients each, seizure prophylaxis in 1 patient, Plavix readjustment in 1 patient, and return to the operating room for an asymptomatic epidural hematoma evacuation in 1 patient. When patients were stratified on the basis of postoperative neurological examination, findings on CT scans altered management in 1.1%, 4.8%, and 9.0% of patients with no new neurological deficits, a nonfocal examination, and focal deficits, respectively. The mean total hospital cost for treating patients who undergo elective aneurysm clipping was $72,227 (± $53,966) (all values are US dollars), and the cost of obtaining a noncontrast head CT scan was $292. Neurologically intact patients required 99 head CT scans, at a cost of $28,908, to obtain 1 head CT scan that influenced medical management. In contrast, patients with a focal neurological deficit required only 11 head CT scans, at a cost of $3212, to obtain 1 head CT scan that changed clinical management.
Although there are no clear guidelines, the large number and high cost of CT scans needed to treat neurologically intact elective aneurysm patients suggest that careful neurological monitoring may be more clinically useful and a better use of hospital resources than routine postoperative CT.
Corinna C. Zygourakis, Janelle Lee, Julio Barba, Errol Lobo and Michael T. Lawton
Concurrent surgeries, also known as “running two rooms” or simultaneous/overlapping operations, have recently come under intense scrutiny. The goal of this study was to evaluate the operative time and outcomes of concurrent versus nonconcurrent vascular neurosurgical procedures.
The authors retrospectively reviewed 1219 procedures performed by 1 vascular neurosurgeon from 2012 to 2015 at the University of California, San Francisco. Data were collected on patient age, sex, severity of illness, risk of mortality, American Society of Anesthesiologists (ASA) status, procedure type, admission type, insurance, transfer source, procedure time, presence of resident or fellow in operating room (OR), number of co-surgeons, estimated blood loss (EBL), concurrent vs nonconcurrent case, severe sepsis, acute respiratory failure, postoperative stroke causing neurological deficit, unplanned return to OR, 30-day mortality, and 30-day unplanned readmission. For aneurysm clipping cases, data were also obtained on intraoperative aneurysm rupture and postoperative residual aneurysm. Chi-square and t-tests were performed to compare concurrent versus nonconcurrent cases, and then mixed-effects models were created to adjust for different procedure types, patient demographics, and clinical indicators between the 2 groups.
There was a significant difference in procedure type for concurrent (n = 828) versus nonconcurrent (n = 391) cases. Concurrent cases were more likely to be routine/elective admissions (53% vs 35%, p < 0.001) and physician referrals (59% vs 38%, p < 0.001). This difference in patient/case type was also reflected in the lower severity of illness, risk of death, and ASA class in the concurrent versus nonconcurrent cases (p < 0.01). Concurrent cases had significantly longer procedural times (243 vs 213 minutes) and more unplanned 30-day readmissions (5.7% vs 3.1%), but shorter mean length of hospital stay (11.2 vs 13.7 days), higher rates of discharge to home (66% vs 51%), lower 30-day mortality rates (3.1% vs 6.1%), lower rates of acute respiratory failure (4.3% vs 8.2%), and decreased 30-day unplanned returns to the OR (3.3% vs 6.9%; all p < 0.05). Rates of severe sepsis, postoperative stroke, intraoperative aneurysm rupture, and postoperative aneurysm residual were equivalent between the concurrent and nonconcurrent groups (all p values nonsignificant). Mixed-effects models showed that after controlling for procedure type, patient demographics, and clinical indicators, there was no significant difference in acute respiratory failure, severe sepsis, 30-day readmission, postoperative stroke, EBL, length of stay, discharge status, or intraoperative aneurysm rupture between concurrent and nonconcurrent cases. Unplanned return to the OR and 30-day mortality were significantly lower in concurrent cases (odds ratio 0.55, 95% confidence interval 0.31–0.98, p = 0.0431, and odds ratio 0.81, p < 0.001, respectively), but concurrent cases had significantly longer procedure durations (odds ratio 21.73; p < 0.001).
Overall, there was a significant difference in the types of concurrent versus nonconcurrent cases, with more routine/elective cases for less sick patients scheduled in an overlapping fashion. After adjusting for patient demographics, procedure type, and clinical indicators, concurrent cases had longer procedure times, but equivalent patient outcomes, as compared with nonconcurrent vascular neurosurgical procedures.
Michael M. Safaee, Cecilia L. Dalle Ore, Corinna C. Zygourakis, Vedat Deviren and Christopher P. Ames
Proximal junctional kyphosis (PJK) is a well-recognized complication of surgery for adult spinal deformity and is characterized by increased kyphosis at the upper instrumented vertebra (UIV). PJK prevention strategies have the potential to decrease morbidity and cost by reducing rates of proximal junctional failure (PJF), which the authors define as radiographic PJK plus clinical sequelae requiring revision surgery.
The authors performed an analysis of 195 consecutive patients with adult spinal deformity. Age, sex, levels fused, upper instrumented vertebra (UIV), use of 3-column osteotomy, pelvic fixation, and mean time to follow-up were collected. The authors also reviewed operative reports to assess for the use of surgical adjuncts targeted toward PJK prevention, including ligament augmentation, hook fixation, and vertebroplasty. The cost of surgery, including direct and total costs, was also assessed at index surgery and revision surgery. Only revision surgery for PJF was included.
The mean age of the cohort was 64 years (range 25–84 years); 135 (69%) patients were female. The mean number of levels fused was 10 (range 2–18) with the UIV as follows: 2 cervical (1%), 73 upper thoracic (37%), 108 lower thoracic (55%), and 12 lumbar (6%). Ligament augmentation was used in 99 cases (51%), hook fixation in 60 cases (31%), and vertebroplasty in 71 cases (36%). PJF occurred in 18 cases (9%). Univariate analysis found that ligament augmentation and hook fixation were associated with decreased rates of PJF. However, in a multivariate model that also incorporated age, sex, and UIV, only ligament augmentation maintained a significant association with PJF reduction (OR 0.196, 95% CI 0.050–0.774; p = 0.020). Patients with ligament augmentation, compared with those without, had a higher cost of index surgery, but ligament augmentation was overall cost effective and produced significant cost savings. In sensitivity analyses in which we independently varied the reduction in PJF, cost of ligament augmentation, and cost of reoperation by ± 50%, ligament augmentation remained a cost-effective strategy for PJF prevention.
Prevention strategies for PJK/PJF are limited, and their cost-effectiveness has yet to be established. The authors present the results of 195 patients with adult spinal deformity and show that ligament augmentation is associated with significant reductions in PJF in both univariate and multivariate analyses, and that this intervention is cost-effective. Future studies will need to determine if these clinical results are reproducible, but for high-risk cases, these data suggest an important role of ligament augmentation for PJF prevention and cost savings.
Corinna C. Zygourakis, A. Karim Ahmed, Samuel Kalb, Alex M. Zhu, Ali Bydon, Neil R. Crawford and Nicholas Theodore
The Excelsius GPS (Globus Medical, Inc.) was approved by the FDA in 2017. This novel robot allows for real-time intraoperative imaging, registration, and direct screw insertion through a rigid external arm—without the need for interspinous clamps or K-wires. The authors present one of the first operative cases utilizing the Excelsius GPS robotic system in spinal surgery. A 75-year-old man presented with severe lower back pain and left leg radiculopathy. He had previously undergone 3 decompressive surgeries from L3 to L5, with evidence of instability and loss of sagittal balance. Robotic assistance was utilized to perform a revision decompression with instrumented fusion from L3 to S1. The usage of robotic assistance in spinal surgery may be an invaluable resource in minimally invasive cases, minimizing the need for fluoroscopy, or in those with abnormal anatomical landmarks.
The video can be found here: https://youtu.be/yVI-sJWf9Iw.
Corinna C. Zygourakis, Seungwon Yoon, Victoria Valencia, Christy Boscardin, Christopher Moriates, Ralph Gonzales and Michael T. Lawton
Disposable supplies constitute a large portion of operating room (OR) costs and are often left over at the end of a surgical case. Despite financial and environmental implications of such waste, there has been little evaluation of OR supply utilization. The goal of this study was to quantify the utilization of disposable supplies and the costs associated with opened but unused items (i.e., “waste”) in neurosurgical procedures.
Every disposable supply that was unused at the end of surgery was quantified through direct observation of 58 neurosurgical cases at the University of California, San Francisco, in August 2015. Item costs (in US dollars) were determined from the authors' supply catalog, and statistical analyses were performed.
Across 58 procedures (36 cranial, 22 spinal), the average cost of unused supplies was $653 (range $89-$3640, median $448, interquartile range $230–$810), or 13.1% of total surgical supply cost. Univariate analyses revealed that case type (cranial versus spinal), case category (vascular, tumor, functional, instrumented, and noninstrumented spine), and surgeon were important predictors of the percentage of unused surgical supply cost. Case length and years of surgical training did not affect the percentage of unused supply cost. Accounting for the different case distribution in the 58 selected cases, the authors estimate approximately $968 of OR waste per case, $242,968 per month, and $2.9 million per year, for their neurosurgical department.
This study shows a large variation and significant magnitude of OR waste in neurosurgical procedures. At the authors' institution, they recommend price transparency, education about OR waste to surgeons and nurses, preference card reviews, and clarification of supplies that should be opened versus available as needed to reduce waste.
Corinna C. Zygourakis, Taemin Oh, Matthew Z. Sun, Igor Barani, James G. Kahn and Andrew T. Parsa
Vestibular schwannomas (VSs) are managed in 3 ways: observation (“wait and scan”); Gamma Knife surgery (GKS); or microsurgery. Whereas there is considerable literature regarding which management approach is superior, there are only a few studies addressing the cost of treating VSs, and there are no cost-utility analyses in the US to date.
In this study, the authors used the University of California at San Francisco medical record and hospital accounting databases to determine total hospital charges and costs for 33 patients who underwent open surgery, 42 patients who had GKS, and 12 patients who were observed between 2010 and 2013. The authors then performed decision-tree analysis to determine which treatment paradigm produces the highest quality-adjusted life years and to calculate the incremental cost-effectiveness ratio, depending on the patient's age at VS diagnosis.
The average total hospital cost over a 3-year period for surgically treated patients was $80,074 (± $49,678) versus $9737 (± $5522) for patients receiving radiosurgery and $1746 (± $2792) for patients who were observed. When modeling the most debilitating symptoms and worst outcomes of VSs (vertigo and death) at different ages at diagnosis, radiation is dominant to observation at all ages up to 70 years. Surgery is cost-effective when compared with radiation (incremental cost-effectiveness ratio < $150,000) at younger ages at diagnosis (< 45 years old).
In this model, surgery is a cost-effective alternative to radiation when VS is diagnosed in patients at < 45 years. For patients ≥ 45 years, radiation is the most cost-effective treatment option.
Martin N. Stienen, Oliver P. Gautschi, Victor E. Staartjes, Nicolai Maldaner, Marketa Sosnova, Allen L. Ho, Anand Veeravagu, Atman Desai, Corinna C. Zygourakis, Jon Park, Luca Regli and John K. Ratliff
Objective functional measures such as the 6-minute walking test (6WT) are increasingly applied to evaluate patients with degenerative diseases of the lumbar spine before and after (surgical) treatment. However, the traditional 6WT is cumbersome to apply, as it requires specialized in-hospital infrastructure and personnel. The authors set out to compare 6-minute walking distance (6WD) measurements obtained with a newly developed smartphone application (app) and those obtained with the gold-standard distance wheel (DW).
The authors developed a free iOS- and Android-based smartphone app that allows patients to measure the 6WD in their home environment using global positioning system (GPS) coordinates. In a laboratory setting, the authors obtained 6WD measurements over a range of smartphone models, testing environments, and walking patterns and speeds. The main outcome was the relative measurement error (rME; in percent of 6WD), with |rME| < 7.5% defined as reliable. The intraclass correlation coefficient (ICC) for agreement between app- and DW-based 6WD was calculated.
Measurements (n = 406) were reliable with all smartphone types in neighborhood, nature, and city environments (without high buildings), as well as with unspecified, straight, continuous, and stop-and-go walking patterns (ICC = 0.97, 95% CI 0.97–0.98, p < 0.001). Measurements were unreliable indoors, in city areas with high buildings, and for predominantly rectangular walking courses. Walking speed had an influence on the ME, with worse accuracy (2% higher rME) for every kilometer per hour slower walking pace (95% CI 1.4%–2.5%, p < 0.001). Mathematical adjustment of the app-based 6WD for velocity-dependent error mitigated the rME (p < 0.011), attenuated velocity dependence (p = 0.362), and had a positive effect on accuracy (ICC = 0.98, 95% CI 0.98–0.99, p < 0.001).
The new, free, spine-specific 6WT smartphone app measures the 6WD conveniently by using GPS coordinates, empowering patients to independently determine their functional status before and after (surgical) treatment. Measurements of 6WD obtained for the target population under the recommended circumstances are highly reliable.