Publications by authors named "Martin N Stienen"

145 Publications

Single vs Multistage Surgical Management of Single and Two-Level Lumbar Degenerative Disease.

World Neurosurg 2021 Jun 1. Epub 2021 Jun 1.

Neurosurgery AI Lab & Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA. Electronic address:

Study Design: Retrospective cohort studying using a national, administrative database.

Objective: To determine the postoperative complications and quality outcomes of single and multi-stage surgical management for lumbar degenerative disease (LDD).

Methods: This study identified patients with who underwent surgery for LDD between 2007 - 2016. Patients were stratified based on whether their surgeon choose to correct their LDD in a single or multistage manner, and these cohorts were mutually exclusive. Propensity score matching (PSM) was then utilized to mitigate intergroup differences between single and multi-stage patients. Patients who underwent three or more levels surgical correction, were under the age of 18 years, or those with any prior history of trauma or tumor were excluded from this study. Baseline comorbidities, postoperative complication rates, and reoperation rates were determined.

Results: A total of 47,190 patients underwent primary surgery for LDD, of which 9,438 (20%) underwent multi-stage surgery. After propensity score matching, baseline covariates of the two cohorts were similar. The complication rate was 6.1% in the single stage cohort and 11.0% in the multistage cohort. Rates of post-hemorrhagic anemia, infection, wound complication, DVT, and hematoma were all higher in the multistage cohort. Lengths of stay, revision, and readmission rates were also significantly higher in the multi-stage cohort. Through 2-years of follow up, multi-stage surgery was associated with higher payments throughout the 2-year follow-up period ($57,036 vs $39,318, p < 0.05).

Conclusion: Single stage surgery for lumbar degenerative disc disease demonstrates improved outcomes and lower healthcare utilization. Spine surgeons should carefully consider single-stage surgery when treating patients with less than three-level LDD.
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http://dx.doi.org/10.1016/j.wneu.2021.05.115DOI Listing
June 2021

Assessment of the Minimum Clinically Important Difference in the Smartphone-Based 6-Minute Walking Test after Surgery for Lumbar Degenerative Disc Disease.

Spine (Phila Pa 1976) 2021 Feb 15. Epub 2021 Feb 15.

aDepartment of Neurosurgery, Kantonsspital St. Gallen, St. Gallen, Switzerland bDepartment of Neurosurgery, University Hospital Zurich & Clinical Neuroscience Center, University of Zurich, Zurich, Switzerland.

Study Design: Prospective cohort study.

Objective: The aim of this study was to determine the minimum clinically important difference (MCID) of the 6-minute walking test (6WT) after surgery for lumbar degenerative disc disease (DDD).

Summary Of Background Data: The smartphone-based 6WT is a valid and reliable tool to quantify objective functional impairment in patients with lumbar DDD. To date, the MCID of the 6WT has not be described in patients with DDD.

Methods: We assessed patients pre- and 6-weeks postoperatively, analysing both raw 6-minute walking distances (6WD; in meters) and standardized 6WT z-scores. Three methods were applied to compute MCID values using established patient-reported outcomes measures (PROMs) as anchors (VAS back/leg pain, Zurich Claudication Questionnaire (ZCQ), Core Outcome Measures Index (COMI)): (1) average change, (2) minimum detectable change, and (3) the change difference approach.

Results: We studied 49 patients (59% male) with a mean age of 55.5 ± 15.8 years. The computation methods revealed MCID values ranging from 81m (z-score of 0.9) based on the VAS back pain to 99m (z-score of 1.0) based on the ZCQ physical function scale. The average MCID of the 6WT was 92m (z-score of 1.0). Based on the average MCID of raw 6WD values or standardized z-scores, 53% or 49% of patients classified as 6-week responders to surgery for lumbar DDD, respectively.

Conclusion: The MCID for the 6WT in lumbar DDD patients is variable, depending on the calculation technique. We propose a MCID of 92m (z-score of 1.0), based on the average of all three methods. Using a z-score as MCID allows for the standardization of clinically meaningful change and attenuates age- and sex-related differences.

Level Of Evidence: 3.
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http://dx.doi.org/10.1097/BRS.0000000000003991DOI Listing
February 2021

Defining and Describing Treatment Heterogeneity in New-Onset Idiopathic Lower Back and Extremity Pain Through Reconstruction of Longitudinal Care Sequences.

Spine J 2021 May 22. Epub 2021 May 22.

Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA. Electronic address:

Background Context: Despite established guidelines, long-term management of surgically-treated low back pain (LBP) and lower extremity pain (LEP) remains heterogeneous. Understanding care heterogeneity could inform future approaches for standardization of practices.

Purpose: To describe treatment heterogeneity in surgically-managed LBP and LEP.

Study Design/setting: Retrospective study of a nationwide commercial database spanning inpatient and outpatient encounters for enrollees of eligible employer-supplied healthcare plans (2007-2016).

Patient Sample: A population-based sample of opioid-naïve adult patients with newly-diagnosed LBP or LEP were identified. Inclusion required at least 12-months of pre-diagnosis and post-diagnosis continuous follow-up.

Exposure: Included treatments/evaluations include conservative management (chiropractic manipulative therapy, physical therapy, epidural steroid injections), imaging (x-ray, MRI, CT), pharmaceuticals (opioids, benzodiazepines), and spine surgery (decompression, fusion).

Outcome Measures: Primary outcomes-of-interest were 12-month net healthcare expenditures (inpatient and outpatient) and 12-month opioid usage.

Methods: Analyses include interrogation of care sequence heterogeneity and temporal trends in sequence-initiating services. Comparisons were conducted in the framework of sequence-specific treatment sequences, which reflect the personalized order of healthcare services pursued by each patient. Outlier sequences characterized by high opioid use and costs were identified from frequently observed surgical treatment sequences using Mahalanobis distance.

Results: A total of 2,496,908 opioid-naïve adult patients with newly-diagnosed LBP or LEP were included (29,519 surgical). In the matched setting, increased care sequence heterogeneity was observed in surgical patients (0.51 vs 0.12 previously-unused interventions/studies pursued per month). Early opioid and MRI use has decreased between 2008 and 2015 but is matched by increases in early benzodiazepine and x-ray use. Outlier sequences, characterized by increased opioid use and costs, were found in 5.8% of surgical patients. Use of imaging prior to conservative management was common in patients pursuing outlier sequences compared to non-outlier sequences (96.5% vs 63.8%, p<0.001). Non-outlier sequences were more frequently characterized by early conservative interventions (31.9% vs 7.4%, p<0.001).

Conclusions: Surgically-managed LBP and LEP care sequences demonstrate high heterogeneity despite established practice guidelines. Outlier sequences associated with high opioid usage and costs can be identified and are characterized by increased early imaging and decreased early conservative management. Elements that may portend suboptimal longitudinal management could provide opportunities for standardization of patient care.
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http://dx.doi.org/10.1016/j.spinee.2021.05.019DOI Listing
May 2021

External Validation of the Minimum Clinically Important Difference in the Timed-Up-and-Go (TUG) Test after Surgery for Lumbar Degenerative Disc Disease.

Spine (Phila Pa 1976) 2021 May 24. Epub 2021 May 24.

Department of Neurosurgery, University Hospital Zurich and Clinical Neuroscience Center, University of Zurich, Zurich, Switzerland Department of Neurosurgery, Cantonal Hospital St.Gallen, St.Gallen, Switzerland Neuro- and Spine Center, Hirslanden Clinic St. Anna, Lucerne, Switzerland.

Study Design: Prospective observational cohort study.

Objective: To provide external validation of the minimum clinically important difference (MCID) of the Timed-Up-and-Go (TUG) test.

Summary Of Background Data: The TUG test is one of the best explored and most frequently applied objective task-based functional outcome measure in patients with lumbar degenerative disc disease (DDD). The increased use of the TUG test is based on its solid psychometric properties, however, an external validation of the originally determined MCID is lacking.

Methods: N = 49 patients with lumbar DDD, scheduled for elective spine surgery, were assessed pre- and 6-weeks (W6) postoperative. MCID values were calculate for raw TUG test times (in s) and standardized TUG z-scores using three different computation methods and the following established patient-reported outcome measures (PROMs) as anchors: Visual Analog Scales (VAS), Core Outcome Measures Index (COMI) Back, Zurich Claudication Questionnaire (ZCQ)).

Results: The three computation methods generated a range of MCID values, depending on the PROM used as anchor, from 0.9 s (z-score of 0.3) based on the VAS leg pain to 3.0 s (z-score of 2.7) based on the ZCQ physical function scale. The average MCID of the TUG test across all anchors and computation methods was 2.1 s (z-score of 1.5). According to the average MCID of raw TUG test values or TUG z-scores, 41% and 43% of patients classified as W6 responders to surgery, respectively.

Conclusion: This study confirms the ordinally reported TUG MCID values in patients undergoing surgery for lumbar. A TUG test time change of 2.1 s (or TUG z-score change of 1.5) indicates an objective and clinically meaningful change in functional status. This report facilitates the interpretation of TUG test results in clinical routine as well as in research.Level of Evidence: 3.
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http://dx.doi.org/10.1097/BRS.0000000000004128DOI Listing
May 2021

Responsiveness of the self-measured 6-minute walking test and the Timed Up and Go test in patients with degenerative lumbar disorders.

J Neurosurg Spine 2021 May 7. Epub 2021 May 7.

Department of Neurosurgery, University Hospital Zurich and Clinical Neuroscience Center, University of Zurich.

Objective: The 6-minute walking test (6WT) and the Timed Up and Go (TUG) test are two of the most commonly applied standardized measures of objective functional impairment that help support clinical decision-making for patients undergoing surgery for degenerative lumbar disorders. This study correlates smartphone-app-based 6WT and TUG results to evaluate their responsiveness.

Methods: In a prospective study, 49 consecutive patients were assessed preoperatively and 6 weeks postoperatively using the 6WT, the TUG test, and commonly used patient-reported outcome measures. Raw values and standardized z-scores of both objective tests were correlated. An external criterion for treatment success was created based on the Zurich Claudication Questionnaire patient satisfaction subscale. Internal and external responsiveness for both functional tests was evaluated.

Results: The mean preoperative 6WT results improved from 401 m (SD 129 m), z-score -1.65 (SD 1.6) to 495 m (SD 129 m), z-score -0.71 (SD 1.6, p < 0.001). The mean preoperative TUG test results improved from 10.44 seconds (SD 4.37, z-score: -3.22) to 8.47 seconds (SD 3.38, z-score: -1.93, p < 0.001). The 6WT showed a strong negative correlation with TUG test results (r = -66, 95% CI 0.76-0.53, p < 0.001). The 6WT showed higher internal responsiveness (standardized responsive mean = 0.86) compared to the TUG test (standardized responsive mean = 0.67). Evaluation of external responsiveness revealed that the 6WT was capable of differentiating between patients who were satisfied and those who were unsatisfied with their treatment results (area under the curve = 0.70), whereas this was not evident for the TUG test ( area under the curve = 0.53).

Conclusions: Both tests adequately quantified functional impairment in surgical candidates with degenerative lumbar disorders. The 6WT demonstrated better internal and external responsiveness compared with the TUG test. Clinical trial registration no.: NCT03977961 (clinicaltrials.gov).

Abbreviations: AUC = area under the curve; COMI = Core Outcome Measures Index; DLDs = degenerative lumbar disorders; LDH = lumbar disc herniation; LSS = lumbar spinal stenosis; PROM = patient-reported outcome measure; ROC = receiver operating characteristic; SRM = standardized responsive mean; TUG = Timed Up and Go; VAS = visual analog scale; 6WD = 6-minute walking distance; 6WT = 6-minute walking test; ZCQ = Zurich Claudication Questionnaire.
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http://dx.doi.org/10.3171/2020.11.SPINE201621DOI Listing
May 2021

Enhanced Recovery After Surgery strategies for elective craniotomy: a systematic review.

J Neurosurg 2021 May 7:1-25. Epub 2021 May 7.

1Machine Intelligence in Clinical Neuroscience (MICN) Laboratory, Department of Neurosurgery, Clinical Neuroscience Center, University Hospital Zurich, University of Zurich, Switzerland.

Objective: Enhanced Recovery After Surgery (ERAS) has led to a paradigm shift in perioperative care through multimodal interventions. Still, ERAS remains a relatively new concept in neurosurgery, and there is no summary of evidence on ERAS applications in cranial neurosurgery.

Methods: The authors systematically reviewed the literature using the PubMed/MEDLINE, Embase, Scopus, and Cochrane Library databases for ERAS protocols and elements. Studies had to assess at least one pre-, peri-, or postoperative ERAS element and evaluate at least one of the following outcomes: 1) length of hospital stay, 2) length of ICU stay, 3) postoperative pain, 4) direct and indirect healthcare cost, 5) complication rate, 6) readmission rate, or 7) patient satisfaction.

Results: A final 27 articles were included in the qualitative analysis, with mixed quality of evidence ranging from high in 3 cases to very low in 1 case. Seventeen studies reported a complete ERAS protocol. Preoperative ERAS elements include patient selection through multidisciplinary team discussion, patient counseling and education to adjust expectations of the postoperative period, and mental state assessment; antimicrobial, steroidal, and antiepileptic prophylaxes; nutritional assessment, as well as preoperative oral carbohydrate loading; and postoperative nausea and vomiting (PONV) prophylaxis. Anesthesiology interventions included local anesthesia for pin sites, regional field block or scalp block, avoidance or minimization of the duration of invasive monitoring, and limitation of intraoperative mannitol. Other intraoperative elements include absorbable skin sutures and avoidance of wound drains. Postoperatively, the authors identified early extubation, observation in a step-down unit instead of routine ICU admission, early mobilization, early fluid de-escalation, early intake of solid food and liquids, early removal of invasive monitoring, professional nutritional assessment, PONV management, nonopioid rescue analgesia, and early postoperative imaging. Other postoperative interventions included discharge criteria standardization and home visits or progress monitoring by a nurse.

Conclusions: A wide range of evidence-based interventions are available to improve recovery after elective craniotomy, although there are few published ERAS protocols. Patient-centered optimization of neurosurgical care spanning the pre-, intra-, and postoperative periods is feasible and has already provided positive results in terms of improved outcomes such as postoperative pain, patient satisfaction, reduced length of stay, and cost reduction with an excellent safety profile. Although fast-track recovery protocols and ERAS studies are gaining momentum for elective craniotomy, prospective trials are needed to provide stronger evidence.
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http://dx.doi.org/10.3171/2020.10.JNS203160DOI Listing
May 2021

[Acute Traumatic Central Cord Syndrome: Etiology, Pathophysiology, Clinical Manifestation, and Treatment].

Praxis (Bern 1994) 2021 Apr;110(6):324-335

Klinik für Neurochirurgie, Kantonsspital St. Gallen, St. Gallen.

Acute Traumatic Central Cord Syndrome: Etiology, Pathophysiology, Clinical Manifestation, and Treatment The acute traumatic central cord syndrome (ATCCS) represents an injury to the spinal cord with disproportionately greater motor impairment of the upper than the lower extremities, with bladder dysfunction and with varying degrees of sensory loss below the level of the respective lesion. The mechanism of ATCCS is most commonly a traumatic hyperextension injury of the cervical spine at the base of an underlying spondylosis and spinal stenosis. The mean age is 53 years, and segments C4 to Th1 are most frequently affected. In addition to medical history and clinical examination, the definitive diagnosis is made by magnetic resonance imaging, where T2-hyperintense lesions are typically observed in the affected spinal cord segment. Surgical decompression (and fusion) of the respective segment is recommended to prevent repetitive trauma to the spinal cord and to stop progression of clinical symptoms. Patients with diagnosed ATCCS and who are treated adequately usually have a good prognosis.
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http://dx.doi.org/10.1024/1661-8157/a003659DOI Listing
April 2021

Hemispherectomy Outcome Prediction Scale: Development and validation of a seizure freedom prediction tool.

Epilepsia 2021 May 13;62(5):1064-1073. Epub 2021 Mar 13.

Department of Pediatrics, BC Children's Hospital and University of British Columbia, Vancouver, British Columbia, Canada.

Objective: To develop and validate a model to predict seizure freedom in children undergoing cerebral hemispheric surgery for the treatment of drug-resistant epilepsy.

Methods: We analyzed 1267 hemispheric surgeries performed in pediatric participants across 32 centers and 12 countries to identify predictors of seizure freedom at 3 months after surgery. A multivariate logistic regression model was developed based on 70% of the dataset (training set) and validated on 30% of the dataset (validation set). Missing data were handled using multiple imputation techniques.

Results: Overall, 817 of 1237 (66%) hemispheric surgeries led to seizure freedom (median follow-up = 24 months), and 1050 of 1237 (85%) were seizure-free at 12 months after surgery. A simple regression model containing age at seizure onset, presence of generalized seizure semiology, presence of contralateral 18-fluoro-2-deoxyglucose-positron emission tomography hypometabolism, etiologic substrate, and previous nonhemispheric resective surgery is predictive of seizure freedom (area under the curve = .72). A Hemispheric Surgery Outcome Prediction Scale (HOPS) score was devised that can be used to predict seizure freedom.

Significance: Children most likely to benefit from hemispheric surgery can be selected and counseled through the implementation of a scale derived from a multiple regression model. Importantly, children who are unlikely to experience seizure control can be spared from the complications and deficits associated with this surgery. The HOPS score is likely to help physicians in clinical decision-making.
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http://dx.doi.org/10.1111/epi.16861DOI Listing
May 2021

Impact of the Coronavirus Disease 2019 Pandemic on Working and Training Conditions of Neurosurgery Residents in Latin America and Spain.

World Neurosurg 2021 06 6;150:e182-e202. Epub 2021 Mar 6.

Department of Neurosurgery. Hospital de Especialidades, Centro Médico Nacional (CMN) Siglo XXI, Instituto Mexicano del Seguro Social (IMSS), México City, México. Electronic address:

Background: The coronavirus disease 2019 (COVID-19) pandemic has exerted a significant impact on health care workers. Recent studies have reported the detrimental effects of the pandemic on neurosurgery residents in North America, Asia, and Italy. However, the impact of the pandemic on neurosurgical training in Latin America and Spain has not yet been reported. In the present report, we describe effects of COVID-19 on training and working conditions of neurosurgery residents in these countries.

Methods: An electronic survey with 33 questions was sent to neurosurgery residents between September 7, 2020 and October 7, 2020. Statistical analysis was made in SPSS version 25.

Results: A total of 293 neurosurgery residents responded. The median age was 29.47 ± 2.6 years, and 79% (n = 231) were male. Of respondents, 36.5% (n = 107) were residents training from Mexico; 42% surveyed reported COVID symptoms and 2 (0.7%) received intensive care unit care; 61.4% of residents had been tested for COVID and 21.5% had a positive result; 84% of the respondents mentioned persisted with the same workload (≥70 hours per week) during the pandemic. Most residents from Mexico were assigned to management of patients with COVID compared with the rest of the countries (88% vs. 68.3%; P < 0.001), mainly in medical care (65.4% vs. 40.9%; P < 0.001), mechanical ventilators (16.8% vs. 5.9%; P = 0.003), and neurologic surgeries (94% vs. 83%; P = 0.006).

Conclusions: Our results offer a first glimpse of the changes imposed by the COVID-19 pandemic on neurosurgical work and training in Latin America and Spain, where health systems rely strongly on a resident workforce.
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http://dx.doi.org/10.1016/j.wneu.2021.02.137DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7936760PMC
June 2021

Risk Factors for Revision Surgery After Primary Adult Thoracolumbar Deformity Surgery.

Clin Spine Surg 2021 Jan 11. Epub 2021 Jan 11.

Neurosurgery AI Laboratory and Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA Department of Neurosurgery, University Hospital Zurich and Clinical Neuroscience Center, University of Zurich, Zurich, Switzerland.

Study Design: This is a retrospective cohort study.

Objective: The aim was to identify the risk factors for revision surgery within 2 years of patients undergoing primary adult spinal deformity (ASD) surgery.

Summary Of Background Data: Previous literature reports estimate 20% of patients undergoing thoracolumbar ASD correction undergo reoperation within 2 years. There is limited published data regarding specific risk factors for reoperation in ASD surgery in the short term and long term.

Methods: The authors queried the MarketScan database in order to identify patients who were diagnosed with a spinal deformity and underwent ASD surgery from 2007 to 2015. Patient-level factors and revision risk were investigated during 2 years after primary ASD surgery. Patients under the age of 18 years and those with any prior history of trauma or tumor were excluded from this study.

Results: A total 7422 patients underwent ASD surgery during 2007-2015 in the data set. Revision rates were 13.1% at 90 days, 14.5% at 6 months, 16.7% at 1 year, and 19.3% at 2 years. In multivariate multiple logistic regression analysis, obesity [adjusted odds ratio (OR): 1.58, P<0.001] and tobacco use (adjusted OR: 1.38, P=0.0011) were associated with increased odds of reoperation within 2 years. Patients with a combined anterior-posterior approach had lower odds of reoperation compared with those with posterior only approach (adjusted OR: 0.66, P=0.0117).

Conclusions: Obesity and tobacco are associated with increased odds of revision surgery within 2 years of index ASD surgery. Male sex and combined surgical approach are associated with decreased odds of revision surgery.
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http://dx.doi.org/10.1097/BSD.0000000000001124DOI Listing
January 2021

Patients undergoing surgery for lumbar degenerative spinal disorders favor smartphone-based objective self-assessment over paper-based patient-reported outcome measures.

Spine J 2021 04 17;21(4):610-617. Epub 2020 Dec 17.

Department of Neurosurgery, Kantonsspital St.Gallen, St. Gallen, Switzerland; Department of Neurosurgery, University Hospital Zurich & Clinical Neuroscience Center, University of Zurich, Zurich, Switzerland.

Background Context: Smartphone-based applications enable new prospects to monitor symptoms and assess functional outcome in patients with lumbar degenerative spinal disorders. However, little is known regarding patient acceptance and preference towards new modes of digital objective outcome assessment.

Purpose: To assess patient preference of an objective smartphone-based outcome measure compared to conventional paper-based subjective methods of outcome assessment.

Study Design: Prospective observational cohort study.

Patient Sample: Fourty-nine consecutive patients undergoing surgery for lumbar degenerative spinal disorder.

Outcome Measures: Patients completed a preference survey to assess different methods of outcome assessment. A 5-level Likert scale ranged from strong disagreement (2 points) over neutral (6 points) to strong agreement (10 points) was used.

Methods: Patients self-determined their objective functional impairment using the 6-minute Walking Test application (6WT-app) and completed a set of paper-based patient-reported outcome measures (PROMs) before and 6 weeks after surgery. Patients were then asked to rate the methods of outcome assessment in terms of suitability, convenience, and responsiveness to their symptoms.

Results: The majority of patients considered the 6WT-app a suitable instrument (median 8.0, interquartile range [IQR] 4.0). Patients found the 6WT more convenient (median 10.0, IQR 2.0) than the Zurich Claudication Questionnaire (ZCQ; median 8.0, IQR 4.0, p=.019) and Core Outcome Measure Index (COMI; median 8.0, IQR 4.0, p=.007). There was good agreement that the 6WT-app detects change in physical performance (8.0, IQR 4.0). 78 % of patients considered the 6WT superior in detecting differences in symptoms (vs. 22% for PROMs). Seventy-six percent of patients would select the 6WT over the other, 18% the ZCQ and 6% the COMI. Eighty-two percent of patients indicated their preference to use a smartphone app for the assessment and monitoring of their spine-related symptoms in the future.

Conclusions: Patients included in this study favored the smartphone-based evaluation of objective functional impairment over paper-based PROMs. Involving patients more actively by means of digital technology may increase patient compliance and satisfaction as well as diagnostic accuracy.
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http://dx.doi.org/10.1016/j.spinee.2020.11.013DOI Listing
April 2021

Association of Medical Comorbidities With Objective Functional Impairment in Lumbar Degenerative Disc Disease.

Global Spine J 2020 Dec 17:2192568220979120. Epub 2020 Dec 17.

Department of Neurosurgery, Clinical Neuroscience Center, University Hospital Zurich, University of Zurich, Zurich, Switzerland.

Study Design: Analysis of a prospective 2-center database.

Objectives: Medical comorbidities co-determine clinical outcome. Objective functional impairment (OFI) provides a supplementary dimension of patient assessment. We set out to study whether comorbidities are associated with the presence and degree of OFI in this patient population.

Methods: Patients with degenerative diseases of the spine preoperatively performed the timed-up-and-go (TUG) test and a battery of questionnaires. Comorbidities were quantified using the Charlson Comorbidity Index (CCI) and the American Society of Anesthesiology (ASA) grading. Crude and adjusted linear regression models were fitted.

Results: Of 375 included patients, 97 (25.9%) presented at least some degree of medical comorbidity according to the CCI, and 312 (83.2%) according to ASA grading. In the univariate analysis, the CCI was inconsistently associated with OFI. Only patients with low-grade CCI comorbidity displayed significantly higher TUG test times (p = 0.004). In the multivariable analysis, this effect persisted for patients with CCI = 1 (p = 0.030). Regarding ASA grade, patients with ASA = 3 exhibited significantly increased TUG test times (p = 0.003) and t-scores (p = 0.015). This effect disappeared after multivariable adjustment (p = 0.786 and p = 0.969). In addition, subjective functional impairment according to ODI, and EQ5D index was moderately associated with comorbidities according to ASA (all p < 0.05).

Conclusion: The degree of medical comorbidities appears only weakly and inconsistently associated with OFI in patients scheduled for degenerative lumbar spine surgery, especially after controlling for potential confounders. TUG testing may be valid even in patients with relatively severe comorbidities who are able to complete the test.
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http://dx.doi.org/10.1177/2192568220979120DOI Listing
December 2020

Incidence and Outcome of Aneurysmal Subarachnoid Hemorrhage: The Swiss Study on Subarachnoid Hemorrhage (Swiss SOS).

Stroke 2021 01 4;52(1):344-347. Epub 2020 Dec 4.

Neuroradiology (L.R., M.D.), Kantonsspital Aarau Switzerland.

Background And Purpose: The purpose of this study was to assess nationwide incidence and outcomes of aneurysmal subarachnoid hemorrhage (aSAH). The Swiss SOS (Swiss Study on Subarachnoid Hemorrhage) was established in 2008 and offers the unique opportunity to provide this data from the point of care on a nationwide level.

Methods: All patients with confirmed aneurysmal subarachnoid hemorrhage admitted between January 1, 2009 and December 31, 2014, within Switzerland were recorded in a prospective registry. Incidence rates were calculated based on time-matched population data. Admission parameters and outcomes at discharge and at 1 year were recorded.

Results: We recorded data of 1787 consecutive patients. The incidence of aneurysmal subarachnoid hemorrhage in Switzerland was 3.7 per 100 000 persons/y. The number of female patients was 1170 (65.5%). With a follow-up rate of 91.3% at 1 year, 1042 patients (58.8%) led an independent life according to the modified Rankin Scale (0-2). About 1 in 10 patients survived in a dependent state (modified Rankin Scale, 3-5; n=185; 10.4%). Case fatality was 20.1% (n=356) at discharge and 22.1% (n=391) after 1 year.

Conclusions: The current incidence of aneurysmal subarachnoid hemorrhage in Switzerland is lower than expected and an indication of a global trend toward decreasing admissions for ruptured intracranial aneurysms. Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT03245866.
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http://dx.doi.org/10.1161/STROKEAHA.120.029538DOI Listing
January 2021

Global adoption of robotic technology into neurosurgical practice and research.

Neurosurg Rev 2020 Nov 30. Epub 2020 Nov 30.

Machine Intelligence in Clinical Neuroscience (MICN) Lab, Department of Neurosurgery, Clinical Neuroscience Center, University Hospital Zurich, University of Zurich, Frauenklinikstrasse 10, 8091, Zurich, Switzerland.

Recent technological advancements have led to the development and implementation of robotic surgery in several specialties, including neurosurgery. Our aim was to carry out a worldwide survey among neurosurgeons to assess the adoption of and attitude toward robotic technology in the neurosurgical operating room and to identify factors associated with use of robotic technology. The online survey was made up of nine or ten compulsory questions and was distributed via the European Association of the Neurosurgical Societies (EANS) and the Congress of Neurological Surgeons (CNS) in February and March 2018. From a total of 7280 neurosurgeons who were sent the survey, we received 406 answers, corresponding to a response rate of 5.6%, mostly from Europe and North America. Overall, 197 neurosurgeons (48.5%) reported having used robotic technology in clinical practice. The highest rates of adoption of robotics were observed for Europe (54%) and North America (51%). Apart from geographical region, only age under 30, female gender, and absence of a non-academic setting were significantly associated with clinical use of robotics. The Mazor family (32%) and ROSA (26%) robots were most commonly reported among robot users. Our study provides a worldwide overview of neurosurgical adoption of robotic technology. Almost half of the surveyed neurosurgeons reported having clinical experience with at least one robotic system. Ongoing and future trials should aim to clarify superiority or non-inferiority of neurosurgical robotic applications and balance these potential benefits with considerations on acquisition and maintenance costs.
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http://dx.doi.org/10.1007/s10143-020-01445-6DOI Listing
November 2020

The World Federation of Neurosurgical Societies Young Neurosurgeons Survey (Part II): Barriers to Professional Development and Service Delivery in Neurosurgery.

World Neurosurg X 2020 Oct 11;8:100084. Epub 2020 May 11.

National Institute for Health Research Global Health Research Group on Neurotrauma, University of Cambridge, Cambridge, United Kingdom.

Background: Strengthening health systems requires attention to workforce, training needs, and barriers to service delivery. The World Federation of Neurosurgical Societies Young Neurosurgeons Committee survey sought to identify challenges for residents, fellows, and consultants within 10 years of training.

Methods: An online survey was distributed to various neurosurgical societies, personal contacts, and social media platforms (April-November 2018). Responses were grouped by World Bank income classification into high-income countries (HICs), upper middle-income countries (UMICs), low-middle-income countries (LMICs), and low-income countries (LICs). Descriptive statistical analysis was performed.

Results: In total, 953 individuals completed the survey. For service delivery, the limited number of trained neurosurgeons was seen as a barrier for 12.5%, 29.8%, 69.2%, and 23.9% of respondents from HICs, UMICs, LMICs, and LICs, respectively ( < 0.0001). The most reported personal challenge was the lack of opportunities for research (HICs, 34.6%; UMICs, 57.5%; LMICs, 61.6%; and LICs, 61.5%;  = 0.03). Other differences by income class included limited access to advice from experienced/senior colleagues ( < 0.001), neurosurgical journals ( < 0.0001), and textbooks ( = 0.02). Assessing how the World Federation of Neurosurgical Societies could best help young neurosurgeons, the most frequent requests ( = 953; 1673 requests) were research ( = 384), education ( = 296), and subspecialty/fellowship training ( = 232). Skills courses and access to cadaver dissection laboratories were also heavily requested.

Conclusions: Young neurosurgeons perceived that additional neurosurgeons are needed globally, especially in LICs and LMICs, and primarily requested additional resources for research and subspecialty training.
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http://dx.doi.org/10.1016/j.wnsx.2020.100084DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7573643PMC
October 2020

Fostering reproducibility and generalizability in machine learning for clinical prediction modeling in spine surgery.

Spine J 2020 Oct 13. Epub 2020 Oct 13.

Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA, USA. Electronic address:

As the use of machine learning algorithms in the development of clinical prediction models has increased, researchers are becoming more aware of the deleterious effects that stem from the lack of reporting standards. One of the most obvious consequences is the insufficient reproducibility found in current prediction models. In an attempt to characterize methods to improve reproducibility and to allow for better clinical performance, we utilize a previously proposed taxonomy that separates reproducibility into 3 components: technical, statistical, and conceptual reproducibility. By following this framework, we discuss common errors that lead to poor reproducibility, highlight the importance of generalizability when evaluating a ML model's performance, and provide suggestions to optimize generalizability to ensure adequate performance. These efforts are a necessity before such models are applied to patient care.
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http://dx.doi.org/10.1016/j.spinee.2020.10.006DOI Listing
October 2020

Predictive modeling of long-term opioid and benzodiazepine use after intradural tumor resection.

Spine J 2020 Oct 13. Epub 2020 Oct 13.

Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA, United States. Electronic address:

Background Context: Despite increased awareness of the ongoing opioid epidemic, opioid and benzodiazepine use remain high after spine surgery. In particular, long-term co-prescription of opioids and benzodiazepines have been linked to high risk of overdose-associated death. Tumor patients represent a unique subset of spine surgery patients and few studies have attempted to develop predictive models to anticipate long-term opioid and benzodiazepine use after spinal tumor resection.

Methods: The IBM Watson Health MarketScan Database and Medicare Supplement were assessed to identify admissions for intradural tumor resection between 2007 and 2015. Adult patients were required to have at least 6 months of continuous preadmission baseline data and 12 months of continuous postdischarge follow-up. Primary outcomes were long-term opioid and benzodiazepine use, defined as at least 6 prescriptions within 12 months. Secondary outcomes were durations of opioid and benzodiazepine prescribing. Logistic regression models, with and without regularization, were trained on an 80% training sample and validated on the withheld 20%.

Results: A total of 1,942 patients were identified. The majority of tumors were extramedullary (74.8%) and benign (62.5%). A minority of patients received arthrodesis (9.2%) and most patients were discharged to home (79.1%). Factors associated with postdischarge opioid use duration include tumor malignancy (vs benign, B=19.8 prescribed-days/year, 95% confidence interval [CI] 1.1-38.5) and intramedullary compartment (vs extramedullary, B=18.1 prescribed-days/year, 95% CI 3.3-32.9). Pre- and perioperative use of prescribed nonsteroidal anti-inflammatory drugs and gabapentin/pregabalin were associated with shorter and longer duration opioid use, respectively. History of opioid and history of benzodiazepine use were both associated with increased postdischarge opioid and benzodiazepine use. Intramedullary location was associated with longer duration postdischarge benzodiazepine use (B=10.3 prescribed-days/year, 95% CI 1.5-19.1). Among assessed models, elastic net regularization demonstrated best predictive performance in the withheld validation cohort when assessing both long-term opioid use (area under curve [AUC]=0.748) and long-term benzodiazepine use (AUC=0.704). Applying our model to the validation set, patients scored as low-risk demonstrated a 4.8% and 2.4% risk of long-term opioid and benzodiazepine use, respectively, compared to 35.2% and 11.1% of high-risk patients.

Conclusions: We developed and validated a parsimonious, predictive model to anticipate long-term opioid and benzodiazepine use early after intradural tumor resection, providing physicians opportunities to consider alternative pain management strategies.
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http://dx.doi.org/10.1016/j.spinee.2020.10.010DOI Listing
October 2020

External Validation of the Timed Up and Go Test as Measure of Objective Functional Impairment in Patients With Lumbar Degenerative Disc Disease.

Neurosurgery 2021 01;88(2):E142-E149

Neuro- and Spine Center, Hirslanden Clinic St. Anna, Lucerne, Switzerland.

Background: The Timed Up and Go (TUG) test is the most commonly applied objective measure of functional impairment in patients with lumbar degenerative disc disease (DDD).

Objective: To demonstrate external content validity of the TUG test.

Methods: Consecutive adult patients, scheduled for elective lumbar spine surgery, were screened for enrollment into a prospective observational study. Disease severity was estimated by patient-reported outcome measures (PROMs; Visual Analog Scales [VAS], Core Outcome Measures Index [COMI] back, Zurich Claudication Questionnaire [ZCQ]) and the TUG test. Pearson correlation coefficients (PCCs) were used to describe the relationship between logarithmic TUG test raw values and PROMs.

Results: A total of 70 patients (mean age 55.9 ± 15.4 yr; 38.6% female; 27.1% previous spine surgery; 28.6% lower extremity motor deficits) with lumbar disc herniation (50%), lumbar spinal stenosis (34.3%), or instability requiring spinal fusion (15.7%) were included. The mean TUG test time was 10.8 ± 4.4 s; age- and sex-adjusted objective functional impairment (OFI) T-score was 134.2 ± 36.9. A total of 12 (17.1%) patients had mild, 14 (20%) moderate, and 9 (12.9%) severe OFI, while 35 (50%) had TUG test results within the normal population range (no OFI). PCCs between TUG test time and VAS back pain were r = 0.37 (P = .002), VAS leg pain r = 0.37 (P = .002), COMI back r = 0.50 (P < .001), ZCQ symptom severity r = 0.41 (P < .001), and ZCQ physical function r = 0.36 (P = .002).

Conclusion: This external validation demonstrated similar OFI rates and PCCs between logarithmic TUG test results and PROMs compared to the original article from 2016. These findings support the TUG test being a quick, easy-to-use objective test, which provides the physician with a robust estimate of pain and functional impairment.
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http://dx.doi.org/10.1093/neuros/nyaa441DOI Listing
January 2021

Evaluating the Impact of Spinal Osteotomy on Surgical Outcomes of Thoracolumbar Deformity Correction.

World Neurosurg 2020 12 18;144:e774-e779. Epub 2020 Sep 18.

Stanford Neurosurgical Artificial Intelligence and Machine Learning Laboratory, Department of Neurosurgery, Stanford University School of Medicine, Stanford, California, USA. Electronic address:

Background: In cases of adult spinal deformity (ASD) with severe sagittal malalignment, the use of osteotomies may be necessary in addition to posterior fusion. However, few data exist describing the impact of osteotomies on complications and quality outcomes during ASD surgery.

Methods: We queried the MarketScan database to identify patients who underwent ASD surgery in 2007-2016. Patients were stratified according to whether or not an osteotomy was used in the index operation. Propensity score matching was used to mitigate intergroup differences between osteotomy and nonosteotomy groups. Patients <18 years old and patients with any prior history of trauma or tumor were excluded from the study.

Results: Of 7423 patients who met the inclusion criteria of this study, 2700 (36.4%) received an osteotomy. After propensity score matching, baseline comorbidities and approach type were similar between cohorts. The overall 90-day complication rate was 43.2% in the nonosteotomy group and 52.8% in the osteotomy group (P < 0.0001). The osteotomy cohort also had significantly higher rates of revision surgeries through 2 years (21.1% vs. 18.0%, P < 0.05) following index surgery. Patients who received a 3-column osteotomy had the highest procedural payments, costing $155,885 through 90 days and $167,161 through 1 year following surgery.

Conclusions: This analysis confirms high costs and complication, readmission, and reoperation rates until 2 years after ASD surgery in general, which are even higher in cases where an osteotomy is required. Future research should explore strategies for optimizing patient outcomes following osteotomy.
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http://dx.doi.org/10.1016/j.wneu.2020.09.072DOI Listing
December 2020

A Comparative Analysis of Patients Undergoing Fusion for Adult Cervical Deformity by Approach Type.

Global Spine J 2021 Jun 13;11(5):626-632. Epub 2020 Apr 13.

10624Stanford University, Stanford, CA, USA.

Study Design: Retrospective cohort study.

Objective: To provide insight into postoperative complications, short-term quality outcomes, and costs of the surgical approaches of adult cervical deformity (ACD).

Methods: A national database was queried from 2007 to 2016 to identify patients who underwent cervical fusion for ACD. Patients were stratified by approach type-anterior, posterior, or circumferential. Patients undergoing anterior and posterior approach surgeries were additionally compared using propensity score matching.

Results: A total of 6575 patients underwent multilevel cervical fusion for ACD correction. Circumferential fusion had the highest postoperative complication rate (46.9% vs posterior: 36.7% vs anterior: 18.5%, < .0001). Anterior fusion patients more commonly required reoperation compared with posterior fusion patients ( < .0001), and 90-day readmission rate was highest for patients undergoing circumferential fusion ( < .0001). After propensity score matching, the complication rate remained higher in the posterior, as compared to the anterior fusion group ( < .0001). Readmission rate also remained higher in the posterior fusion group; however, anterior fusion patients were more likely to require reoperation. At index hospitalization, posterior fusion led to 1.5× higher costs, and total payments at 90 days were 1.6× higher than their anterior fusion counterparts.

Conclusion: Patients who undergo posterior fusion for ACD have higher complication rates, readmission rates, and higher cost burden than patients who undergo anterior fusion; however, posterior correction of ACD is associated with a lower rate of reoperation.
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http://dx.doi.org/10.1177/2192568220915717DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8165914PMC
June 2021

Postoperative Complication Burden, Revision Risk, and Health Care Use in Obese Patients Undergoing Primary Adult Thoracolumbar Deformity Surgery.

Global Spine J 2021 Apr 25;11(3):345-350. Epub 2020 Feb 25.

6429Stanford University School of Medicine, Stanford, CA, USA.

Study Design: This is a retrospective cohort study using a nationally representative administrative database.

Objective: To identify the impact of obesity on postoperative outcomes in patients undergoing thoracolumbar adult spinal deformity (ASD) surgery.

Background: The obesity rate in the United States remains staggering, with approximately one-third of all Americans being overweight or obese. However, the impact of elevated body mass index on spine surgery outcomes remains unclear.

Methods: We queried the MarketScan database to identify patients who were diagnosed with a spinal deformity and underwent ASD surgery from 2007 to 2016. Patients were then stratified by whether or not they were diagnosed as obese at index surgical admission. Propensity score matching (PSM) was then utilized to mitigate intergroup differences between obese and nonobese patients. Patients <18 years and those with any prior history of trauma or tumor were excluded from this study. Baseline demographics and comorbidities, postoperative complication rates, and short- and long-term reoperation rates were determined.

Results: A total of 7423 patients met the inclusion criteria of this study, of whom 597 (8.0%) were obese. Initially, patients with obesity had a higher 90-day postoperative complication rate than nonobese patients (46.1% vs 40.8%, < .05); however, this difference did not remain after PSM. Revision surgery rates after 2 years were similar across the 2 groups following primary surgery (obese, 21.4%, vs nonobese, 22.0%; = .7588). Health care use occurred at a higher rate among obese patients through 2 years of long-term follow-up (obese, $152 930, vs nonobese, $140 550; < .05).

Conclusion: Patients diagnosed with obesity who underwent ASD surgery did not demonstrate increased rates of complications, reoperations, or readmissions. However, overall health care use through 2 years of follow-up after index surgery was higher in the obesity cohort.
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http://dx.doi.org/10.1177/2192568220904341DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8013946PMC
April 2021

Machine learning in neurosurgery: a global survey.

Acta Neurochir (Wien) 2020 12 18;162(12):3081-3091. Epub 2020 Aug 18.

Machine Intelligence in Clinical Neuroscience (MICN) Lab, Department of Neurosurgery, Clinical Neuroscience Center, University Hospital Zurich, University of Zurich, Frauenklinikstrasse 10, 8091, Zurich, Switzerland.

Background: Recent technological advances have led to the development and implementation of machine learning (ML) in various disciplines, including neurosurgery. Our goal was to conduct a comprehensive survey of neurosurgeons to assess the acceptance of and attitudes toward ML in neurosurgical practice and to identify factors associated with its use.

Methods: The online survey consisted of nine or ten mandatory questions and was distributed in February and March 2019 through the European Association of Neurosurgical Societies (EANS) and the Congress of Neurosurgeons (CNS).

Results: Out of 7280 neurosurgeons who received the survey, we received 362 responses, with a response rate of 5%, mainly in Europe and North America. In total, 103 neurosurgeons (28.5%) reported using ML in their clinical practice, and 31.1% in research. Adoption rates of ML were relatively evenly distributed, with 25.6% for North America, 30.9% for Europe, 33.3% for Latin America and the Middle East, 44.4% for Asia and Pacific and 100% for Africa with only two responses. No predictors of clinical ML use were identified, although academic settings and subspecialties neuro-oncology, functional, trauma and epilepsy predicted use of ML in research. The most common applications were for predicting outcomes and complications, as well as interpretation of imaging.

Conclusions: This report provides a global overview of the neurosurgical applications of ML. A relevant proportion of the surveyed neurosurgeons reported clinical experience with ML algorithms. Future studies should aim to clarify the role and potential benefits of ML in neurosurgery and to reconcile these potential advantages with bioethical considerations.
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http://dx.doi.org/10.1007/s00701-020-04532-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7593280PMC
December 2020

Procedures performed during neurosurgery residency in Europe.

Acta Neurochir (Wien) 2020 10 16;162(10):2303-2311. Epub 2020 Aug 16.

Department of Neurosurgery, Geneva University Hospitals, Geneva, Switzerland.

Background: In a previous article ( https://doi.org/10.1007/s00701-019-03888-3 ), preliminary results of a survey, aiming to shed light on the number of surgical procedures performed and assisted during neurosurgery residency in Europe were reported. We here present the final results and extend the analyses.

Methods: Board-certified neurosurgeons of European Association of Neurosurgical Societies (EANS) member countries were asked to review their residency case logs and participate in a 31-question electronic survey (SurveyMonkey Inc., San Mateo, CA). The responses received between April 25, 2018, and April 25, 2020, were considered. We excluded responses that were incomplete, from non-EANS member countries, or from respondents that have not yet completed their residency.

Results: Of 430 responses, 168 were considered for analysis after checking in- and exclusion criteria. Survey responders had a mean age of 42.7 ± 8.8 years, and 88.8% were male. Responses mainly came from surgeons employed at university/teaching hospitals (85.1%) in Germany (22.0%), France (12.5%), the United Kingdom (UK; 8.3%), Switzerland (7.7%), and Greece (7.1%). Most responders graduated in the years between 2011 and 2019 (57.7%). Thirty-eight responders (22.6%) graduated before and 130 responders (77.4%) after the European WTD 2003/88/EC came into effect. The mean number of surgical procedures performed independently, supervised or assisted throughout residency was 540 (95% CI 424-657), 482 (95% CI 398-568), and 579 (95% CI 441-717), respectively. Detailed numbers for cranial, spinal, adult, and pediatric subgroups are presented in the article. There was an annual decrease of about 33 cases in total caseload between 1976 and 2019 (coeff. - 33, 95% CI - 62 to - 4, p = 0.025). Variables associated with lesser total caseload during residency were training abroad (1210 vs. 1747, p = 0.083) and female sex by trend (947 vs. 1671, p = 0.111), whereas case numbers were comparable across the EANS countries (p = 0.443).

Conclusion: The final results of this survey largely confirm the previously reported numbers. They provide an opportunity for current trainees to compare their own case logs with. Again, we confirm a significant decline in surgical exposure during training between 1976 and 2019. In addition, the current analysis reveals that female sex and training abroad may be variables associated with lesser case numbers during residency.
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http://dx.doi.org/10.1007/s00701-020-04513-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7496021PMC
October 2020

Association Between Physician Industry Payments and Cost of Anterior Cervical Discectomy and Fusion in Medicare Beneficiaries.

World Neurosurg 2020 11 10;143:e574-e580. Epub 2020 Aug 10.

Department of Neurosurgery, Johns Hopkins School of Medicine, Baltimore, Maryland, USA; Center for Healthcare Value, University of California, San Francisco, California, USA; Department of Neurological Surgery, University of California, San Francisco, California, USA; Department of Neurological Surgery, Stanford University, Palo Alto, California, USA. Electronic address:

Background: Neurosurgical spine specialists receive considerable amounts of industry support that may impact the cost of care. The aim of this study was to evaluate the association between industry payments received by spine surgeons and the total hospital and operating room (OR) costs of an anterior cervical discectomy and fusion (ACDF) procedure among Medicare beneficiaries.

Methods: All ACDF cases were identified among the Medicare carrier files from January 1, 2013, to December 31, 2014, and matched to the Medicare inpatient baseline file. The total hospital and OR charges were obtained for these cases. Charges were converted to cost using year-specific cost-to-charge ratios. Surgeons were identified among the Open Payments database, which is used to quantify industry support. Analyses were performed to examine the association between industry payments received and ACDF costs.

Results: Matching resulting in the inclusion of 2209 ACDF claims from 2013-2014. In 2013 and 2014, the mean total cost for an ACDF was $21,798 and $21,008, respectively; mean OR cost was $5878 and $6064, respectively. Mann-Whitney U test demonstrated no significant differences in the mean total or OR cost for an ACDF based on quartile of general industry payment received (P = 0.21 and P = 0.54), and linear regression found no association between industry general payments, research support, or investments on the total hospital cost (P = 0.41, P = 0.13, and P = 0.25, respectively), or OR cost for an ACDF (P = 0.35, P = 0.24, and P = 0.40, respectively).

Conclusions: This study suggests that spine surgeons performing ACDF surgeries may receive industry support without impacting the cost of care.
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http://dx.doi.org/10.1016/j.wneu.2020.08.023DOI Listing
November 2020

Evaluation of the 6-minute walking test as a smartphone app-based self-measurement of objective functional impairment in patients with lumbar degenerative disc disease.

J Neurosurg Spine 2020 08 7;33(6):779-788. Epub 2020 Aug 7.

1Department of Neurosurgery, University Hospital Zurich and Clinical Neuroscience Center, University of Zurich.

Objective: Digital transformation enables new possibilities to assess objective functional impairment (OFI) in patients with lumbar degenerative disc disease (DDD). This study examines the psychometric properties of an app-based 6-minute walking test (6WT) and determines OFI in patients with lumbar DDD.

Methods: The maximum 6-minute walking distance (6WD) was determined in patients with lumbar DDD. The results were expressed as raw 6WDs (in meters), as well as in standardized z-scores referenced to age- and sex-specific values of spine-healthy volunteers. The 6WT results were assessed for reliability and content validity using established disease-specific patient-reported outcome measures.

Results: Seventy consecutive patients and 330 volunteers were enrolled. The mean 6WD was 370 m (SD 137 m) in patients with lumbar DDD. Significant correlations between 6WD and the Core Outcome Measures Index for the back (r = -0.31), Zurich Claudication Questionnaire (ZCQ) symptom severity (r = -0.32), ZCQ physical function (r = -0.33), visual analog scale (VAS) for back pain (r = -0.42), and VAS for leg pain (r = -0.32) were observed (all p < 0.05). The 6WT revealed good test-retest reliability (intraclass correlation coefficient 0.82), and the standard error of measurement was 58.3 m. A 4-tier severity stratification classified patients with z-scores > -1 (no OFI), -1 to -1.9 (mild OFI), -2 to -2.9 (moderate OFI), and ≤ -3 (severe OFI).

Conclusions: The smartphone app-based self-measurement of the 6WT is a convenient, reliable, and valid way to determine OFI in patients with lumbar DDD. The 6WT app facilitates the digital evaluation and monitoring of patients with lumbar DDD.
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http://dx.doi.org/10.3171/2020.5.SPINE20547DOI Listing
August 2020

Complications, Costs, and Quality Outcomes of Patients Undergoing Cervical Deformity Surgery With Intraoperative BMP Use.

Spine (Phila Pa 1976) 2020 Nov;45(22):1553-1558

Neurosurgery AI Lab & Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA.

Study Design: An epidemiological study using national administrative data from the MarketScan database.

Objective: The aim of this study was to identify the impact of bone morphogenetic protein (BMP) on postoperative outcomes in patients undergoing adult cervical deformity (ACD) surgery.

Summary Of Background Data: BMP has been shown to stimulate bone growth and improve fusion rates in spine surgery. However, the impact of BMP on reoperation rates and postoperative complication rate is controversial.

Methods: We queried the MarketScan database to identify patients who underwent ACD surgery from 2007 to 2015. Patients were stratified by BMP use in the index operation. Patients <18 years and those with any history of tumor or trauma were excluded. Baseline demographics and comorbidities, postoperative complication rates, and reoperation rates were analyzed.

Results: A total of 13,549 patients underwent primary ACD surgery, of which 1155 (8.5%) had intraoperative BMP use. The overall 90-day complication rate was 27.6% in the non-BMP cohort and 31.1% in the BMP cohort (P < 0.05). Patients in the BMP cohort had longer average length of stay (4.0 days vs. 3.7 days, P < 0.05) but lower revision surgery rates at 90 days (14.5% vs. 28.3%, P < 0.05), 6 months (14.9% vs. 28.6%, P < 0.05), 1 year (15.7% vs. 29.2%, P < 0.05), and 2 years (16.5% vs. 29.9%, P < 0.05) postoperatively. BMP use was associated with higher payments throughout the 2-year follow-up period ($107,975 vs. $97,620, P < 0.05). When controlling for baseline group differences, BMP use independently increased the odds of postoperative complication (odds ratio [OR] 1.22, 95% confidence interval [CI] 1.1-1.4) and reduced the odds of reoperation throughout 2 years of follow-up (OR 0.49, 95% CI 0.4-0.6).

Conclusion: Intraoperative BMP use has benefits for fusion integrity in ACD surgery but is associated with increased postoperative complication rate. Spine surgeons should weigh these benefits and drawbacks to identify optimal candidates for BMP use in ACD surgery.

Level Of Evidence: 3.
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http://dx.doi.org/10.1097/BRS.0000000000003629DOI Listing
November 2020

[Tuberculous Spondylitis - Diagnosis and Management].

Praxis (Bern 1994) 2020 Aug;109(10):775-787

Interdisziplinäres Wirbelsäulenzentrum, Universitätsspital Zürich, Universität Zürich.

Tuberculous Spondylitis - Diagnosis and Management Despite a decreasing incidence of tuberculosis (TB) over the last decades in Switzerland, the frequency of newly diagnosed tuberculous spondylitis has remained stable. It occurs most frequently in old, immunocompromised persons and/or persons who have moved to Switzerland from TB endemic areas. It is a chronic manifestation of TB, which is characterized by 'cold abscesses', neurological deficits and kyphotic spinal deformity. Tuberculous spondylitis is often diagnosed with a delay, which can lead to higher morbidity and treatment complexity. Antibiotic therapy is essential in tuberculous spondylitis. Surgical interventions aim to obtain samples, decompress nervous structures, obtain pain control and, if necessary, deformity correction/stabilization. This paper provides an overview of the modern diagnostic and therapeutic management of tuberculous spondylitis in Switzerland.
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http://dx.doi.org/10.1024/1661-8157/a003518DOI Listing
August 2020

Predictors of 2-year reoperation in Medicare patients undergoing primary thoracolumbar deformity surgery.

J Neurosurg Spine 2020 Jul 24:1-5. Epub 2020 Jul 24.

1Neurosurgery AI Lab & Department of Neurosurgery, Stanford University School of Medicine, Stanford, California; and.

Objective: This was a retrospective cohort study in which the authors used a nationally representative administrative database. Their goal was to identify the risk factors for reoperation in Medicare patients undergoing primary thoracolumbar adult spinal deformity (ASD) surgery. Previous literature reports estimate that 20% of patients undergoing thoracolumbar ASD correction undergo revision surgery within 2 years. Most published data discuss risk factors for revision surgery in the general population, but these have not been explored specifically in the Medicare population.

Methods: Using the MarketScan Medicare Supplemental database, the authors identified patients who were diagnosed with a spinal deformity and underwent ASD surgery between 2007 and 2015. The interactions of patient demographics, surgical factors, and medical factors with revision surgery were investigated during the 2 years following primary ASD surgery. The authors excluded patients without Medicare insurance and those with any prior history of trauma or tumor.

Results: Included in the data set were 2564 patients enrolled in Medicare who underwent ASD surgery between 2007 and 2015. The mean age at diagnosis with spinal deformity was 71.5 years. A majority of patients (68.5%) were female. Within 2 years of follow-up, 661 (25.8%) patients underwent reoperation. Preoperative osteoporosis (OR 1.58, p < 0.0001), congestive heart failure (OR 1.35, p = 0.0161), and paraplegia (OR 2.41, p < 0.0001) independently increased odds of revision surgery. The use of intraoperative bone morphogenetic protein was protective against reoperation (OR 0.71, p = 0.0371). Among 90-day postoperative complications, a wound complication was the strongest predictor of undergoing repeat surgery (OR 2.85, p = 0.0061). The development of a pulmonary embolism also increased the odds of repeat surgery (OR 1.84, p = 0.0435).

Conclusions: Approximately one-quarter of Medicare patients with ASD who underwent surgery required an additional spinal surgery within 2 years. Baseline comorbidities such as osteoporosis, congestive heart failure, and paraplegia, as well as short-term complications such as pulmonary embolism and wound complications significantly increased the odds of repeat surgery.
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http://dx.doi.org/10.3171/2020.5.SPINE191425DOI Listing
July 2020

Single- versus dual-attending strategy for spinal deformity surgery: 2-year experience and systematic review of the literature.

J Neurosurg Spine 2020 Jul 10:1-12. Epub 2020 Jul 10.

2Neurosurgery, Stanford University Hospitals and Clinics, Stanford, California.

Objective: Adult spinal deformity (ASD) surgery is complex and associated with high morbidity and complication rates. There is growing evidence in the literature for the beneficial effects of an approach to surgery in which two attending physicians rather than a single attending physician perform surgery for and oversee the surgical care of a single patient in a dual-attending care model. The authors developed a dual-attending care collaboration in August 2017 in which a neurosurgeon and an orthopedic surgeon mutually operated on patients with ASD.

Methods: The authors recorded data for 2 years of experience with ASD patients operated on by dual attending surgeons. Analyses included estimated blood loss (EBL), transfusions, length of stay (LOS), discharge disposition, complication rates, emergency room visits and readmissions, subjective health status improvement, and disability (Oswestry Disability Index [ODI] score) and pain (visual analog scale [VAS] score) at last follow-up. In addition, the pertinent literature for dual-attending spinal deformity correction was systematically reviewed.

Results: The study group comprised 19 of 254 (7.5%) consecutively operated patients who underwent thoracolumbar fusion during the period from January 2017 to June 2019 (68.4% female; mean patient age 65.1 years, ODI score 44.5, VAS pain score 6.8). The study patients were matched by age, sex, anesthesia risk, BMI, smoking status, ODI score, VAS pain score, prior spine surgeries, and basic operative characteristics (type of interbody implants, instrumented segments, pelvic fixation) to 19 control patients (all p > 0.05). There was a trend toward less EBL (mean 763 vs 1524 ml, p = 0.059), fewer intraoperative red blood cell transfusions (mean 0.5 vs 2.3, p = 0.079), and fewer 90-day readmissions (0% vs 15.8%, p = 0.071) in the dual-attending group. LOS and discharge disposition were similar, as were the rates of any < 30-day postsurgery complications, < 90-day postsurgery emergency room visits, and reoperations, and ODI and VAS pain scores at last follow-up (all p > 0.05). At last follow-up, 94.7% vs 68.4% of patients in the dual- versus single-attending group stated their health status had improved (p = 0.036). In the authors' literature search of prior articles on spinal deformity correction, 5 of 8 (62.5%) articles reported lower EBL and 6 of 8 (75%) articles reported significantly lower operation duration in dual-attending cases. The literature contained differing results with regard to complication- or reoperation-sparing effects associated with dual-attending cases. Similar clinical outcomes of dual- versus single-attending cases were reported.

Conclusions: Establishing a dual-attending care management platform for ASD correction was feasible at the authors' institution. Results of the use of a dual-attending strategy at the authors' institution were favorable. Positive safety and outcome profiles were found in articles on this topic identified by a systematic literature review.
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http://dx.doi.org/10.3171/2020.3.SPINE2016DOI Listing
July 2020

Tenosynovial giant cell tumor of the suboccipital region - A rare, benign neoplasm in this location.

J Clin Neurosci 2020 Aug 4;78:413-415. Epub 2020 Jul 4.

Department of Neurosurgery, Stanford University, Stanford, CA, United States.

Tenosynovial giant cell tumors (TGCTs) are benign neoplasms that arise from the synovium of tendon sheaths, bursae, and joints. We report a rare presentation of TGCT involving the suboccipital spine.
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http://dx.doi.org/10.1016/j.jocn.2020.05.022DOI Listing
August 2020