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Andrea M. Simmonds, Y. Raja Rampersaud, Marcel F. Dvorak, Nicolas Dea, Angela D. Melnyk and Charles G. Fisher

OBJECT

A range of surgical options exists for the treatment of degenerative lumbar spondylolisthesis (DLS). The chosen technique inherently depends on the stability of the DLS. Despite a substantial body of literature dedicated to the outcome analysis of numerous DLS procedures, no consensus has been reached on defining or classifying the disorder with respect to stability or the role that instability should play in a treatment algorithm. The purpose of this study was to define grades of stability and to develop a guide for deciding on the optimal approach in surgically managing patients with DLS.

METHODS

The authors conducted a qualitative systematic review of clinical or biomechanical analyses evaluating the stability of and surgical outcomes for DLS for the period from 1990 to 2013. Research focused on nondegenerative forms of spondylolisthesis or spinal stenosis without associated DLS was excluded. The primary extracted results were clinical and radiographic parameters indicative of DLS instability.

RESULTS

The following preoperative parameters are predictors of stability in DLS: restabilization signs (disc height loss, osteophyte formation, vertebral endplate sclerosis, and ligament ossification), no disc angle change or less than 3 mm of translation on dynamic radiographs, and the absence of low-back pain. The validity and magnitude of each parameter’s contribution can only be determined through appropriately powered prospective evaluation in the future. Identifying these parameters has allowed for the creation of a preliminary DLS instability classification (DSIC) scheme based on the preoperative assessment of DLS stability.

CONCLUSIONS

Spinal stability is an important factor to consider in the evaluation and treatment of patients with DLS. Qualitative assessment of the best available evidence revealed clinical and radiographic parameters for the creation of the DSIC, a decision aid to help surgeons develop a method of preoperative evaluation to better stratify DLS treatment options.

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Nicolas Dea, Martin Borduas, Brendan Kenny, David Fortin and David Mathieu

Object

Brain metastases are the most frequently occurring cerebral tumors. Tumors that are located in eloquent cerebral parenchyma can cause considerable morbidity and may pose a significant challenge during surgery. Gamma Knife surgery (GKS) is a recognized treatment modality for brain metastases. This study was undertaken to assess the safety and efficacy of GKS, specifically for brain metastases in eloquent locations.

Methods

Charts of patients harboring brain metastases that were treated by GKS at the Centre Hospitalier Universitaire de Sherbrooke between August 2004 and April 2008 were reviewed. Planning images were assessed by an independent neurosurgeon to assess tumor location. Eloquent locations included the primary motor, somatosensory, speech, and visual cortices; the basal ganglia; the thalamus; and the brainstem. Data on survival, tumor response, and complications were analyzed and compared with data published on surgical treatment of these lesions.

Results

During the study period, 650 metastases in 295 patients were treated with GKS; of these, 164 metastases in 95 patients were located in eloquent areas. In this subgroup, the median age of patients was 59 years and women constituted 57.9% of the population. The median Karnofsky Performance Scale score was 80% (range 50%–100%). Patients were categorized according to their recursive partitioning analysis class: Class 1, 22.1%; Class 2, 70.5%; and Class 3, 7.4% of patients. Non–small cell lung cancer was the most common primary tumor (63.2% of metastases), followed by small cell lung (8.4%), breast (7.4%), colorectal (5.3%), and renal cell (4.2%) cancers, as well as melanoma (4.2%). The median dose to the tumor margin was 18 Gy (range 14–24 Gy). The median duration of survival after GKS was 8.2 months. The recursive partitioning analysis class was the most significant variable affecting survival (p < 0.0001). Immediate control was achieved in 92.9% of tumors, and 68.6% of tumors were still controlled at the last follow-up. The median time to tumor progression was 16 months. Higher margin dose (p = 0.002), the absence of edema (p = 0.009), and the non–small cell lung cancer tissue type (p = 0.035) positively affected response rates. Steroid medications were no longer used in 46% of patients after GKS. New neurological deficits occurred in 5.7% of patients and seizures in 5.7%. All these deficits were transient and patients completely recovered in response to a temporary course of steroids. Imaging studies showed that new edema occurred in 8.6% of treated metastases and biopsy-proven radiation necrosis in 1.4%.

Conclusions

Gamma Knife surgery is safe and effective for brain metastases located in eloquent areas.

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John T. Street, R. Andrew Glennie, Nicolas Dea, Christian DiPaola, Zhi Wang, Michael Boyd, Scott J. Paquette, Brian K. Kwon, Marcel F. Dvorak and Charles G. Fisher

OBJECTIVE

The objective of this study was to determine if there is a significant difference in surgical site infection (SSI) when comparing the Wiltse and midline approaches for posterior instrumented interbody fusions of the lumbar spine and, secondarily, to evaluate if the reoperation rates and specific causes for reoperation were similar for both approaches.

METHODS

A total of 358 patients who underwent 1- or 2-level posterior instrumented interbody fusions for degenerative lumbar spinal pathology through either a midline or Wiltse approach were prospectively followed between March 2005 and January 2011 at a single tertiary care facility. A retrospective analysis was performed primarily to evaluate the incidence of SSI and the incidence and causes for reoperation. Secondary outcome measures included intraoperative complications, blood loss, and length of stay. A matched analysis was performed using the Fisher's exact test and a logistic regression model. The matched analysis controlled for age, sex, comorbidities, number of index levels addressed surgically, number of levels fused, and the use of bone grafting.

RESULTS

All patients returned for follow-up at 1 year, and adverse events were followed for 2 years. The rate of SSI was greater in the midline group (8 of 103 patients; 7.8%) versus the Wiltse group (1 of 103 patients; 1.0%) (p = 0.018). Fewer additional surgical procedures were performed in the Wiltse group (p = 0.025; OR 0.47; 95% CI 0.23–0.95). Proximal adjacent segment failure requiring reoperation occurred more frequently in the midline group (15 of 103 patients; 14.6%) versus the Wiltse group (6 of 103 patients; 5.8%) (p = 0.048). Blood loss was significantly lower in the Wiltse group (436 ml) versus the midline group (703 ml); however, there was no significant difference between the 2 groups in intraoperative complications or length of stay.

CONCLUSIONS

The patients who underwent the Wiltse approach had a decreased risk of wound breakdown and infection, less blood loss, and fewer reoperations than the midline patients. The risk of adjacent segment failure in short posterior constructs is lower with a Wiltse approach.

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Christian P. DiPaola, Nicolas Dea, Marcel F. Dvorak, Robert S. Lee, Dennis Hartig and Charles G. Fisher

Object

Conflict of interest (COI) as it applies to medical education and training has become a source of considerable interest, debate, and regulation in the last decade. Companies often pay surgeons as faculty for educational events and often sponsor and give financial support to major professional society meetings. Professional medical societies, industry, and legislators have attempted to regulate potential COI without consideration for public opinion. The practice of evidence-based medicine requires the inclusion of patient opinion along with best available evidence and expert opinion. The primary goal of this study was to assess the opinion of the general population regarding surgeon-industry COI for education-related events.

Methods

A Web-based survey was administered, with special emphasis on the surgeon's role in industry-sponsored education and support of professional societies. A survey was constructed to sample opinions on reimbursement, disclosure, and funding sources for educational events.

Results

There were 501 completed surveys available for analysis. More than 90% of respondents believed that industry funding for surgeons' tuition and travel for either industry-sponsored or professional society educational meetings would either not affect the quality of care delivered or would cause it to improve. Similar results were generated for opinions on surgeons being paid by industry to teach other surgeons. Moreover, the majority of respondents believed it was ethical or had no opinion if surgeons had such a relationship with industry. Respondents were also generally in favor of educational conferences for surgeons regardless of funding source. Disclosures of a surgeon-industry relationship, especially if it involves specific devices that may be used in their surgery, appears to be important to respondents.

Conclusions

The vast majority of respondents in this study do not believe that the quality of their care will be diminished due to industry funding of educational events, for surgeon tuition, and/or travel expenses. The results of this study should help form the basis of policy and continued efforts at surgeon-industry COI management.

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Tony Goldschlager, Nicolas Dea, Michael Boyd, Jeremy Reynolds, Shreyaskumar Patel, Laurence D. Rhines, Ehud Mendel, Marina Pacheco, Edwin Ramos, Tobias A. Mattei and Charles G. Fisher

OBJECT

Giant cell tumors (GCTs) of the spine are rare and complex to treat. They have a propensity for local recurrence and the potential to metastasize. Treatment is currently surgical and presents unique challenges due to the proximity of neural structures and the need for reconstruction. Denosumab has been shown in clinical trials to be an effective treatment for GCT, but has not yet been studied specifically in GCT of the spine or as a surgical adjunct. To the authors' knowledge this is the first such reported series.

METHODS

A multicenter, prospective series of 5 patients with GCT of the spine treated with denosumab were included. Patient demographic data, oncological history, neurological status, tumor staging, treatment details and adverse events, surgical procedure, complications, radiological and histological responses, and patient outcome were analyzed.

RESULTS

All patients were women, with a mean age of 38 years, and presented with pain; 2 patients had additional neurological signs and symptoms. The mean duration of symptoms was 62 weeks. No patient had a prior tumor or metastatic disease at presentation. All patients had Enneking Stage III tumors and were treated with monthly cycles of 120 mg of denosumab, with initial additional loading doses on Days 8 and 15. Patients were given daily supplements of calcium (500 mg) and vitamin D (400 IU). There were no denosumab-related adverse events. All patients had a radiological response to denosumab. One patient failed to have a histological response to denosumab, with > 90% of tumor cells found to be viable on histological investigation.

CONCLUSIONS

This study reports the early experience of using denosumab in the treatment of spinal GCT. The results demonstrate a clinically beneficial radiological response and an impressive histological response in most but not all patients. Further experience with denosumab and longer patient follow-up is required. Denosumab has the potential to change the treatment paradigm for spinal GCT.

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Nicolas Dea, Anne Versteeg, Charles Fisher, Adrienne Kelly, Dennis Hartig, Michael Boyd, Scott Paquette, Brian K. Kwon, Marcel Dvorak and John Street

Object

Most descriptions of spine surgery morbidity and mortality in the literature are retrospective. Emerging prospective analyses of adverse events (AEs) demonstrate significantly higher rates, suggesting underreporting in retrospective and prospective studies that do not include AEs as a targeted outcome. Emergency oncological spine surgeries are generally palliative to reduce pain and improve patients' neurology and health-related quality of life. In individuals with limited life expectancy, AEs can have catastrophic implications; therefore, an accurate AE incidence must be considered in the surgical decision-making process. The purpose of this study was to determine the true incidence of AEs associated with emergency oncological spine surgery.

Methods

The authors carried out a prospective cohort study in a quaternary care referral center that included consecutive patients admitted between January 1, 2009, and December 31, 2012. Inclusion criteria were all patients undergoing emergency surgery for metastatic spine disease. AE data were reported and collected on standardized AE forms (Spine AdVerse Events Severity System, version 2 [SAVES V2] forms) at weekly dedicated morbidity and mortality rounds attended by attending surgeons, residents, fellows, and nursing staff.

Results

A total of 101 patients (50 males, 51 females) met the inclusion criteria and had complete data. Seventysix patients (76.2%) had at least 1 AE, and 11 patients (10.9%) died during their admission. Intraoperative surgical AEs were observed in 32% of patients (9.9% incidental durotomy, 16.8% blood loss > 2 L). Transient neurological deterioration occurred in 6 patients (5.9%). Infectious complications in this patient population were significant (surgical site 6%, other 50.5%). Delirium complicated the postoperative period in 20.8% of cases.

Conclusions

When evaluated in a rigorous prospective manner, metastatic spine surgery is associated with a higher morbidity rate than previously reported. This AE incidence must be considered by the patient, oncologist, and surgeon to determine appropriate management and preventative strategies to reduce AEs in this fragile patient population.

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Anne L. Versteeg, Nicolas Dea, Stefano Boriani, Peter P. Varga, Alessandro Luzzati, Michael G. Fehlings, Mark H. Bilsky, Laurence D. Rhines, Jeremy J. Reynolds, Mark. B. Dekutoski, Ziya L. Gokaslan, Niccole M. Germscheid and Charles G. Fisher

OBJECTIVE

Osteoblastoma is a rare primary benign bone tumor with a predilection for the spinal column. Although of benign origin, osteoblastomas tend to behave more aggressively clinically than other benign tumors. Because of the low incidence of osteoblastomas, evidence-based treatment guidelines and high-quality research are lacking, which has resulted in inconsistent treatment. The goal of this study was to determine whether application of the Enneking classification in the management of spinal osteoblastomas influences local recurrence and survival time.

METHODS

A multicenter database of patients who underwent surgical intervention for spinal osteoblastoma was developed by the AOSpine Knowledge Forum Tumor. Patient data pertaining to demographics, diagnosis, treatment, cross-sectional survival, and local recurrence were collected. Patients in 2 cohorts, based on the Enneking classification of the tumor (Enneking appropriate [EA] and Enneking inappropriate [EI]), were analyzed. If the final pathology margin matched the Enneking-recommended surgical margin, the tumor was classified as EA; if not, it was classified as EI.

RESULTS

A total of 102 patients diagnosed with a spinal osteoblastoma were identified between November 1991 and June 2012. Twenty-nine patients were omitted from the analysis because of short follow-up time, incomplete survival data, or invalid staging, which left 73 patients for the final analysis. Thirteen (18%) patients suffered a local recurrence, and 6 (8%) patients died during the study period. Local recurrence was strongly associated with mortality (relative risk 9.2; p = 0.008). When adjusted for Enneking appropriateness, this result was not altered significantly. No significant differences were found between the EA and EI groups in regard to local recurrence and mortality.

CONCLUSIONS

In this evaluation of the largest multicenter cohort of spinal osteoblastomas, local recurrence was found to be strongly associated with mortality. Application of the Enneking classification as a treatment guide for preventing local recurrence was not validated.

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Jin W. Tee, Carly S. Rivers, Nader Fallah, Vanessa K. Noonan, Brian K. Kwon, Charles G. Fisher, John T. Street, Tamir Ailon, Nicolas Dea, Scott Paquette and Marcel F. Dvorak

OBJECTIVE

The aim of this study was to use decision tree modeling to identify optimal stratification groups considering both the neurological impairment and spinal column injury and to investigate the change in motor score as an example of a practical application. Inherent heterogeneity in spinal cord injury (SCI) introduces variation in natural recovery, compromising the ability to identify true treatment effects in clinical research. Optimized stratification factors to create homogeneous groups of participants would improve accurate identification of true treatment effects.

METHODS

The analysis cohort consisted of patients with acute traumatic SCI registered in the Vancouver Rick Hansen Spinal Cord Injury Registry (RHSCIR) between 2004 and 2014. Severity of neurological injury (American Spinal Injury Association Impairment Scale [AIS grades A–D]), level of injury (cervical, thoracic), and total motor score (TMS) were assessed using the International Standards for Neurological Classification of Spinal Cord Injury examination; morphological injury to the spinal column assessed using the AOSpine classification (AOSC types A–C, C most severe) and age were also included. Decision trees were used to determine the most homogeneous groupings of participants based on TMS at admission and discharge from in-hospital care.

RESULTS

The analysis cohort included 806 participants; 79.3% were male, and the mean age was 46.7 ± 19.9 years. Distribution of severity of neurological injury at admission was AIS grade A in 40.0% of patients, grade B in 11.3%, grade C in 18.9%, and grade D in 29.9%. The level of injury was cervical in 68.7% of patients and thoracolumbar in 31.3%. An AOSC type A injury was found in 33.1% of patients, type B in 25.6%, and type C in 37.8%. Decision tree analysis identified 6 optimal stratification groups for assessing TMS: 1) AOSC type A or B, cervical injury, and age ≤ 32 years; 2) AOSC type A or B, cervical injury, and age > 32–53 years; 3) AOSC type A or B, cervical injury, and age > 53 years; 4) AOSC type A or B and thoracic injury; 5) AOSC type C and cervical injury; and 6) AOSC type C and thoracic injury.

CONCLUSIONS

Appropriate stratification factors are fundamental to accurately identify treatment effects. Inclusion of AOSC type improves stratification, and use of the 6 stratification groups could minimize confounding effects of variable neurological recovery so that effective treatments can be identified.

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Nicolas Dea, Charles G. Fisher, Jeremy J. Reynolds, Joseph H. Schwab, Laurence D. Rhines, Ziya L. Gokaslan, Chetan Bettegowda, Arjun Sahgal, Áron Lazáry, Alessandro Luzzati, Stefano Boriani, Alessandro Gasbarrini, Ilya Laufer, Raphaële Charest-Morin, Feng Wei, William Teixeira, Niccole M. Germscheid, Francis J. Hornicek, Thomas F. DeLaney, John H. Shin and the AOSpine Knowledge Forum Tumor

OBJECTIVE

The purpose of this study was to investigate the spectrum of current treatment protocols for managing newly diagnosed chordoma of the mobile spine and sacrum.

METHODS

A survey on the treatment of spinal chordoma was distributed electronically to members of the AOSpine Knowledge Forum Tumor, including neurosurgeons, orthopedic surgeons, and radiation oncologists from North America, South America, Europe, Asia, and Australia. Survey participants were pre-identified clinicians from centers with expertise in the treatment of spinal tumors. The suvey responses were analyzed using descriptive statistics.

RESULTS

Thirty-nine of 43 (91%) participants completed the survey. Most (80%) indicated that they favor en bloc resection without preoperative neoadjuvant radiation therapy (RT) when en bloc resection is feasible with acceptable morbidity. The main area of disagreement was with the role of postoperative RT, where 41% preferred giving RT only if positive margins were achieved and 38% preferred giving RT irrespective of margin status. When en bloc resection would result in significant morbidity, 33% preferred planned intralesional resection followed by RT, and 33% preferred giving neoadjuvant RT prior to surgery. In total, 8 treatment protocols were identified: 3 in which en bloc resection is feasible with acceptable morbidity and 5 in which en bloc resection would result in significant morbidity.

CONCLUSIONS

The results confirm that there is treatment variability across centers worldwide for managing newly diagnosed chordoma of the mobile spine and sacrum. This information will be used to design an international prospective cohort study to determine the most appropriate treatment strategy for patients with spinal chordoma.