Research experience
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Jan 1997–
Dec 2012Research: Medical College of Wisconsin
Medical College of Wisconsin · Department of NeurosurgeryUSA · Milwaukee
Publications (24) View all
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Article: The diagnosis and management of synovial cysts: Efficacy of surgery versus cyst aspiration.
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ABSTRACT: The surgical management of lumbar synovial cysts that have extruded into the spinal canal remains controversial (e.g. decompression with/without fusion). The neurological presentation, anatomy, pathophysiology, and surgical challenges posed by synovial cysts in the lumbar spine are well known. Neurological complaints typically include unilateral or, more rarely, bilateral radicular complaints, and/or cauda equina syndromes. Anatomically, synovial cysts constitute cystic dilatations of synovial sheaths that directly extrude from facet joints into the spinal canal. Pathophysiologically, these cysts reflect disruption of the facet joints often with accompanying instability, and potentially compromise both the cephalad and caudad nerve roots. Aspiration of lumbar synovial cysts, which are typically gelatinous and non-aspirable, and typically performed by "pain specialists" (e.g. pain management, rehabilitation, radiologists, others) utilizing fluoroscopy or CT-guided aspiration, is associated with 50-100% failure rates. Surgical decompression with/without fusion (as the issue regarding fusion remains unsettled) results in the resolution of back and radicular pain in 91.6-92.5% and 91.1-91.9% of cases, respectively. After a thorough review of the literature, it appears that the treatment with the best outcome for patients with synovial cysts is cyst removal utilizing surgical decompression; the need for attendant fusion remains unsettled. The use of an alternative treatment, percutaneous aspiration of cysts, appears to have a much higher recurrence and failure rate, but may be followed by surgery if warranted.Surgical neurology international. 01/2012; 3(Suppl 3):S157-66. -
Article: Controversies in Chiari I malformations.
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ABSTRACT: The diagnosis and management of Chiari I malformations (CMI) remains controversial, particularly since it is often an incidental finding on cervical MR scans performed for neck pain and/or headaches. Recently, some surgeons "over-operated" on asymptomatic patients with Chiari I malformations, or even on those without the requisite radiographic diagnostic features for Chiari I malformations: unfortunately, only a subset were admonished for indiscriminate surgery. Nevertheless, when this hindbrain malformation is truly symptomatic, contributing to impaired cerebrospinal fluid (CSF) circulation, various valid surgical management strategies may be adopted. This review focuses on the current literature regarding the clinical presentation, diagnosis, and surgical management of Chiari I malformation. Variations in the surgical technique are also presented and critiqued. The recommended treatment for Chiari I malformations I consists of decompressive suboccipital craniectomy and duroplasty when abnormal cine-flow MRI is observed preoperatively and blockage of CSF flow persists intraoperatively despite bony decompression. Controversy continues regarding the optimal surgical technique to address Chiari malformations I. Proper diagnostic studies and patient selection are needed to optimize patient outcomes, while avoiding unnecessary surgical procedures.Surgical neurology international. 01/2012; 3(Suppl 3):S232-7. -
Article: An evidence-based clinical guideline for the use of antithrombotic therapies in spine surgery.
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ABSTRACT: The objective of the North American Spine Society (NASS) Evidence-Based Clinical Guideline on antithrombotic therapies in spine surgery was to provide evidence-based recommendations to address key clinical questions surrounding the use of antithrombotic therapies in spine surgery. The guideline is intended to address these questions based on the highest quality clinical literature available on this subject as of February 2008. The goal of the guideline recommendations was to assist in delivering optimum, efficacious treatment with the goal of preventing thromboembolic events. To provide an evidence-based, educational tool to assist spine surgeons in minimizing the risk of deep venous thrombosis (DVT) and pulmonary embolism (PE). Systematic review and evidence-based clinical guideline. This report is from the Antithrombotic Therapies Work Group of the NASS Evidence-Based Guideline Development Committee. The work group was composed of multidisciplinary spine care specialists, all of whom were trained in the principles of evidence-based analysis. Each member of the group was involved in formatting a series of clinical questions to be addressed by the group. The final questions agreed on by the group are the subject of this report. A literature search addressing each question and using a specific search protocol was performed on English language references found in MEDLINE, EMBASE (Drugs and Pharmacology), and four additional, evidence-based databases. The relevant literature was then independently rated by at least three reviewers using the NASS-adopted standardized levels of evidence. An evidentiary table was created for each of the questions. Final grades of recommendation for the answers to each clinical question were arrived at via Web casts among members of the work group using standardized grades of recommendation. When Level I to IV evidence was insufficient to support a recommendation to answer a specific clinical question, expert consensus was arrived at by the work group through the modified nominal group technique and is clearly identified as such in the guideline. Fourteen clinical questions were formulated, addressing issues of incidence of DVT and PE in spine surgery and recommendations regarding utilization of mechanical prophylaxis and chemoprophylaxis in spine surgery. The answers to these 14 clinical questions are summarized in this article. The respective recommendations were graded by the strength of the supporting literature that was stratified by levels of evidence. A clinical guideline addressing the use of antithrombotic therapies in spine surgery has been created using the techniques of evidence-based medicine and using the best available evidence as a tool to assist spine surgeons in minimizing the risk of DVT and PE. The entire guideline document, including the evidentiary tables, suggestions for future research, and all references, is available electronically at the NASS Web site (www.spine.org) and will remain updated on a timely schedule.The spine journal: official journal of the North American Spine Society 12/2009; 9(12):1046-51. · 2.90 Impact Factor -
Article: A new PMHS model for lumbar spine injuries during vertical acceleration.
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ABSTRACT: Ejection from military aircraft exerts substantial loads on the lumbar spine. Fractures remain common, although the overall survivability of the event has considerably increased over recent decades. The present study was performed to develop and validate a biomechanically accurate experimental model for the high vertical acceleration loading to the lumbar spine that occurs during the catapult phase of aircraft ejection. The model consisted of a vertical drop tower with two horizontal platforms attached to a monorail using low friction linear bearings. A total of four human cadaveric spine specimens (T12-L5) were tested. Each lumbar column was attached to the lower platform through a load cell. Weights were added to the upper platform to match the thorax, head-neck, and upper extremity mass of a 50th percentile male. Both platforms were raised to the drop height and released in unison. Deceleration characteristics of the lower platform were modulated by foam at the bottom of the drop tower. The upper platform applied compressive inertial loads to the top of the specimen during deceleration. All specimens demonstrated complex bending during ejection simulations, with the pattern dependent upon the anterior-posterior location of load application. The model demonstrated adequate inter-specimen kinematic repeatability on a spinal level-by-level basis under different subfailure loading scenarios. One specimen was then exposed to additional tests of increasing acceleration to induce identifiable injury and validate the model as an injury-producing system. Multiple noncontiguous vertebral fractures were obtained at an acceleration of 21 g with 488 g/s rate of onset. This clinically relevant trauma consisted of burst fracture at L1 and wedge fracture at L4. Compression of the vertebral body approached 60% during the failure test, with -6,106 N axial force and 168 Nm flexion moment. Future applications of this model include developing a better understanding of the vertebral injury mechanism during pilot ejection and developing tolerance limits for injuries sustained under a variety of different vertical acceleration scenarios.Journal of Biomechanical Engineering 08/2011; 133(8):081002. · 1.90 Impact Factor -
Article: An evidence-based clinical guideline for the diagnosis and treatment of cervical radiculopathy from degenerative disorders.
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ABSTRACT: The North American Spine Society (NASS) Evidence-Based Clinical Guideline on the Diagnosis and Treatment of Cervical Radiculopathy from Degenerative Disorders provides evidence-based recommendations on key clinical questions concerning the diagnosis and treatment of cervical radiculopathy from degenerative disorders. The guideline addresses these questions based on the highest quality clinical literature available on this subject as of May 2009. The guideline's recommendations assist the practitioner in delivering optimum efficacious treatment of and functional recovery from this common disorder. Provide an evidence-based educational tool to assist spine care providers in improving quality and efficiency of care delivered to patients with cervical radiculopathy from degenerative disorders. Systematic review and evidence-based clinical guideline. This report is from the Cervical Radiculopathy from Degenerative Disorders Work Group of the NASS' Evidence-Based Clinical Guideline Development Committee. The work group consisted of multidisciplinary spine care specialists trained in the principles of evidence-based analysis. Each member of the group formatted a series of clinical questions to be addressed by the group. The final questions agreed on by the group are the subjects of this report. A literature search addressing each question using a specific search protocol was performed on English language references found in MEDLINE, EMBASE (Drugs and Pharmacology), and four additional evidence-based databases. The relevant literature was then independently rated by a minimum of three reviewers using the NASS-adopted standardized levels of evidence. An evidentiary table was created for each of the questions. Final recommendations to answer each clinical question were arrived at via work group discussion, and grades were assigned to the recommendations using standardized grades of recommendation. In the absence of Levels I to IV evidence, work group consensus statements have been developed using a modified nominal group technique, and these statements are clearly identified as such in the guideline. Eighteen clinical questions were formulated, addressing issues of natural history, diagnosis, and treatment of cervical radiculopathy from degenerative disorders. The answers are summarized in this article. The respective recommendations were graded by the strength of the supporting literature, which was stratified by levels of evidence. A clinical guideline for cervical radiculopathy from degenerative disorders has been created using the techniques of evidence-based medicine and best available evidence to aid both practitioners and patients involved with the care of this condition. The entire guideline document, including the evidentiary tables, suggestions for future research, and all references, is available electronically at the NASS Web site (www.spine.org) and will remain updated on a timely schedule.The spine journal: official journal of the North American Spine Society 01/2011; 11(1):64-72. · 2.90 Impact Factor
