Michael P Steinmetz

Cleveland Clinic, Cleveland, OH, USA

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Publications (62)155.13 Total impact

  • Article: Relationship between degree of focal kyphosis correction and neurological outcomes for patients undergoing cervical deformity correction surgery.
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    ABSTRACT: Object Reversal of the normal cervical spine curvature, as seen in cervical kyphosis, can lead to mechanical pain, neurological dysfunction, and functional disabilities. Surgical intervention is warranted in patients with sufficiently symptomatic deformities in an attempt to correct the deformed cervical spine. In theory, improved outcomes should accompany a greater degree of correction toward lordosis, although there are few data available to test this relationship. The purpose of this study is to determine if the degree of deformity correction correlates with improvement in neurological symptoms following surgery for cervical kyphotic deformity. Methods A retrospective review of 36 patients with myelopathic symptoms who underwent cervical deformity correction surgery between 2001 and 2009 was performed. Preoperative and postoperative radiographic findings related to the degree of kyphosis were collected and compared with functional outcome measures. The minimum follow-up time was 2 years. Results A significant relationship was observed between a greater degree of focal kyphosis correction and improved neurological outcomes according to the modified Japanese Orthopaedic Association (mJOA) score (r = -0.46, p = 0.032). For patients with severe neurological symptoms (mJOA score < 12) a trend toward improved outcomes with greater global kyphosis correction was observed (r = -0.56, p = 0.057). Patients with an mJOA score less than 16 who attained lordosis postoperatively had a significantly greater improvement in total mJOA score than patients who maintained a kyphotic position (achieved lordosis: 2.7 ± 2.0 vs maintained kyphosis: 1.1 ± 2.1, p = 0.044). Conclusions The authors' results suggest that the degree of correction of focal kyphosis deformity correlates with improved neurological outcomes. The authors also saw a positive relationship between attainment of global lordosis and improved mJOA scores. With consideration for the risks involved in correction surgery, this information can be used to help guide surgical strategy decision making.
    Journal of neurosurgery. Spine 04/2013; · 1.61 Impact Factor
  • Article: Adverse Events With the Use of rhBMP-2 in Thoracolumbar and Lumbar Spine Fusions: A Nine Year Institutional Analysis.
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    ABSTRACT: STUDY DESIGN:: Retrospective chart review. OBJECT:: To describe the adverse outcomes associated with the use of rhBMP-2 in thoracolumbar and lumbar fusions. SUMMARY OF BACKGROUND DATA:: rhBMP-2 has been increasingly used in spinal fusions over the past decade. Early studies reported that the use of rhBMP-2 is associated with decreased operative time, blood loss, and pain scores, as well as improved fusion rates. Recent investigations have shown rhBMP-2 to be associated with various complications occurring at incidences ranging from 0 to 100%. METHODS:: Using the institutional electronic medical records, we retrospectively reviewed all patients between January 2002 and September 2010 that underwent thoracolumbar and lumbar spine fusion with BMP. Patient demographics, operative, and outcome/complication information was collected. RESULTS:: 547 patient charts were reviewed with a mean follow-up time of 17 months. Mean age was 58 years. Forty-one percent of patients had undergone previous spine surgery. Thirty-nine percent of patients had a PLIF/TLIF, 29% underwent a PLF, and 20% an ALIF. No relevant differences in the patient characteristics and complications were identified between the various surgical approaches. For all approaches, having undergone a previous spine surgery was associated with increased incidence of radiculitis, reoperation, and pseudoarthrosis (P=0.005, P=0.0008, P=0.05, respectively) as compared to those without previous spine surgery. Being a current smoker at the time of operation was associated with increased rate of radiculitis (P=0.03) as compared to non-smokers. CONCLUSIONS:: The use of rhBMP-2, in this study, had an incidence of radiculitis, pseudoarthrosis, and reoperation that was similar to the rates in historical controls without rhBMP-2. Complications do not differ by surgical approach, but are more likely in current smokers and those undergoing revision surgery. A prospective study is warranted to further delineate the adverse event profile of rhBMP-2 and the variables that are likely to affect it (i.e. type of surgery, carrier, and dose).
    Journal of spinal disorders & techniques 02/2013; · 1.21 Impact Factor
  • Article: Urological complications following use of recombinant human bone morphogenetic protein-2 in anterior lumbar interbody fusion.
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    ABSTRACT: Object The goal of this study was to compare the urological complications in patients after anterior lumbar interbody fusion (ALIF) with and without the use of recombinant human bone morphogenetic protein-2 (rhBMP-2). Methods The authors retrospectively reviewed the medical records of all patients who underwent ALIF with and without rhBMP-2 between January 2002 and August 2010. Patient demographic, operative, and complication information was analyzed. Male patients who underwent ALIF between L-4 and S-1 were contacted to assess postoperative urological complications. Results Of the 110 male patients who underwent ALIF and were included in this study, 59 were treated with rhBMP-2 and 51 did not receive rhBMP-2. The mean follow-up duration was 17.5 months for the rhBMP-2 group and 30.8 months for the control group. No difference was found regarding the total number of urological complications in the rhBMP-2 group versus the control group (22% vs 20%, respectively; p = 1.0) or for retrograde ejaculation specifically (8% vs 8%, respectively; p = 1.0). Conclusions In this study, the use of rhBMP-2 with ALIF surgery was not associated with an increased incidence of urological complications and retrograde ejaculation when compared with control ALIF without rhBMP-2. Further prospective analyses that specifically look at these complications are warranted.
    Journal of neurosurgery. Spine 12/2012; · 1.61 Impact Factor
  • Article: Letter to the Editor: Direct Lateral Approach to Pathology at the Craniocervical Junction.
    Neurosurgery 11/2012; · 2.79 Impact Factor
  • Article: Lateral Extracavitary versus Costotransversectomy Approaches to the Thoracic Spine: Reflections on Lessons Learned.
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    ABSTRACT: BACKGROUND:: The lateral extracavitary approach (LECA) and costotransversectomy (CTE) are two dorsolateral approaches that avoid entrance into the pleural cavity and facilitate ventral decompression. The indications and outcomes of each of these approaches have not been fully defined in the literature. OBJECTIVE:: To assess the techniques, indications, and complications associated with the LECA and CTE approaches to the thoracic spine. METHODS:: A retrospective analysis was performed on all patients who underwent LECA and CTE between 2000 and 2009 at our institution. RESULTS:: A total of 54 patient charts were reviewed (19 LECA, 35 CTE). Indications for operation included disc herniation, trauma, tumor, osteomyelitis, and scoliosis/kyphosis. Osteomyelitis was treated significantly more often with LECA (47%) than with CTE (9%) (p=0.002). Mean blood loss was 2134 mL and 1556 mL (p=0.3) in LECA and CTE, respectively, and hospital stay was 17.2 days for LECA and 9.8 days for CTE (p=0.07). There were 13 patients (68%) with pre- or postoperative complications for LECA and 19 patients (54%) with CTE (p=1.0). CONCLUSION:: LECA was used more often to treat complex pathologies such as osteomyelitis, and trended towards significance for more frequent use in extensive procedures involving one or two level corpectomies. As can be expected, CTE was associated with slightly less blood loss and a shorter hospital stay compared to the more extensive LECA operation. Adverse outcomes occurred with similar frequency for CTE and LECA.
    Neurosurgery 08/2012; · 2.79 Impact Factor
  • Article: Repair of pars interarticularis defect utilizing a pedicle and laminar screw construct: a new technique based on anatomical and biomechanical analysis.
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    ABSTRACT: The theoretical advantage of pars interarticularis repair over spinal fusion to correct pars defects is that the treatment is a direct osteosynthesis that preserves motion at the involved functional spinal unit. Several techniques and constructs have been used to achieve greater rigidity, but these techniques may risk entry into the spinal canal, and adverse events are common. A pedicle and laminar screw construct placed entirely outside the spinal canal may offer greater stiffness and achieve higher pars defect healing rates. The purpose of this study was to biomechanically assess an intralaminar screw construct in cadaveric lumbar spines in comparison with other types of constructs typically used in pars repair and to quantify the sizes of screws that can be placed safely in both normal and spondylolytic vertebrae. The L-4 and L-5 laminae in patients with spondylolysis and in controls who underwent CT (n = 41, each group) were measured by analysis of conventional axial CT images and multiplanar reformations constructed on a Vitrea workstation to determine the feasibility of translaminar fixation with a 4.5-mm-diameter screw. Biomechanical tests for torsion and flexion-extension were performed on 8 fresh human cadaveric lumbar spines before and after modeling for bilateral spondylolytic defects. Three pars repair techniques were tested at each level and in the following sequence: pedicle screw-cable, pedicle screw-rod-hook, and pedicle screw-intralaminar screw. The majority of laminae can accept 4.5 × 25-mm screws. The cable construct allowed the greatest motion and least stability across the defect in all biomechanical tests. The hook and laminar screw constructs performed similarly in all tests and exhibited no significant difference in stiffness. A surgically placed intralaminar screw construct may be a safe and effective alternative to current pars repair methods.
    Journal of neurosurgery. Spine 05/2012; 17(1):61-8. · 1.61 Impact Factor
  • Article: Radiation exposure to the spine surgeon in lumbar and thoracolumbar fusions with the use of an intraoperative computed tomographic 3-dimensional imaging system.
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    ABSTRACT: A prospective clinical research article. The primary goals were to determine (1) radiation exposure to the spine surgeon with the use of an intraoperative 3-dimensional imaging system and (2) to define the safe distance from the computed tomographic scanner. Intraoperative radiation exposure to the spinal surgeon has been assessed during 2-dimensional fluoroscopy but has not been investigated during intraoperative 3-dimensional imaging. Ten patients undergoing lumbar or thoracolumbar fusion were enrolled in a prospective trial to determine the radiation exposure to a spine surgeon standing in the substerile room, with the use of the O-ARM Imaging System (Medtronic, Memphis, TN). A thermolucent digital dosimeter was worn at chest level without a lead apron. Dosimeter readings and distance from the spine surgeon were recorded. RESULTS.: Average surgeon exposure was 44.22 ± 17.4 μrem (range: 17.71-70.76 μrem). The mean distance from the O-ARM was 4.56 ± .32 m, and the surgeon was exposed for an average of 19.6 ± 5.7 seconds (range: 8.05-28.7 s). The annual number of necessary procedures required to surpass the exposure limit, according to the data presented here, would be 113,071 operations using O-ARM. Hence, the number of necessary procedures for O-ARM use is predicted to be 1,130,710 annual procedures to reach the occupational exposure limits for extremity, skin, and all other organs and 339,213 procedures to reach the limits for the lens of eye. Radiation exposure is minimal to the surgical team during routine use of the O-ARM imaging system. The number of procedures required to surpass occupational exposure limits is high if using appropriate distance from the O-ARM.
    Spine 04/2012; 37(17):E1074-8. · 2.08 Impact Factor
  • Article: Comparing vertebral body reconstruction implants for the treatment of thoracic and lumbar metastatic spinal tumors: a consecutive case series of 37 patients.
    Sharad Rajpal, Roy Hwang, Thomas Mroz, Michael P Steinmetz
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    ABSTRACT: Retrospective case series. To compare different interbody reconstruction implants after corpectomy in metastatic spine tumors. Vertebral body reconstruction after corpectomy is common for patients with metastatic spine tumors. Although various implants are reported individually in the literature, no study to-date has compared them with one another directly. Thirty-seven consecutive patients with metastatic tumors of the thoracic or lumbar spine underwent single or multilevel corpectomy with subsequent interbody reconstruction. Longevity of interbody graft was primarily evaluated in this study as defined by the need for any revision surgeries or complications after surgery. Data was collected retrospectively. Twenty-seven, 5, and 5 patients underwent reconstruction with metal implants, bone implants, and polymethylmethacrylate (PMMA), respectively. Twenty-three patients had metastatic tumor involvement of the thoracic spine and 14 patients had tumor involvement of the lumbar spine. Three patients (8.1%) required additional surgery: 1 wound infection, 1 hardware revision, and 1 for resection of an intradural, intramedullary tumor not identified at the first operation. Overall complication rate was 43.2% (16 patients) and 2 patients died within 30 days of their index spine surgery. Postoperative complication rates were more than double in the metal implant group (52%) compared with an equal number of complications in bone (20%) and PMMA (20%) implant group. The rate of revision surgery was highest in the bone group (40%) compared with none in the PMMA and only 3.7% in the metal interbody groups. Vertebral body reconstruction after corpectomy for patients with metastatic tumors to the thoracic and lumbar spine can be performed effectively with metal, bone, or cement implants. Although metal implants are used in the majority of reconstruction cases, they seem to have a higher rate of overall complications, with bone interbody constructs showing a higher rate of revision surgery.
    Journal of spinal disorders & techniques 04/2012; 25(2):85-91. · 1.21 Impact Factor
  • Article: Translaminar screw fixation in the subaxial cervical spine: quantitative laminar analysis and feasibility of unilateral and bilateral translaminar virtual screw placement.
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    ABSTRACT: Morphometric and volumetric analyses and virtual screw placement. The aim of the study was to (1) define the morphometric and volumetric dimensions of the laminae of C3-C7 and (2) analyze the feasibility of unilateral and bilateral translaminar screw placement at C3-C7. Previous studies on translaminar screw fixation have primarily focused on upper cervical and thoracic fixation. Most studies have been conducted on the subaxial cervical vertebrae in the pediatric population and a few in the adult population. In this study, we used computed tomographic (CT) scans to calculate the spatial anatomical environment for translaminar screws at C3-C7. We also determined the feasibility of translaminar screw placement at C3-C7 for clinical applicability. Morphometric and volumetric analyses were performed on CT scans of the C3-C7 laminae in 25 male and 25 female patients. A total of 2000 morphometric and 1000 volumetric measurements were performed. The feasibility analysis was performed using unilateral and bilateral virtual screw placement via BrainLAB software (BrainLAB AG, Heimstetten, Germany) on the same CT scans. Male patients had significantly (P < 0.05) longer translaminar lengths (C5-C7), sagittal-diagonal measurements (C3-C7), and larger volumes (C6-C7) than female patients. Unilaterally, C7 showed 3.5-mm translaminar screw acceptance rates of 100%, C6 showed high acceptance rates (>64%), and C3-C5 showed lower acceptance rates (<52%). C7 accepted bilateral placement at a high rate (96% men, 84% women). C3 and C6 accepted bilateral screws at low placement rates (8%-24%). C4 and C5 never accepted bilateral translaminar screw placement. Subaxial cervical unilateral translaminar screw placement is a potentially safe and effective technique to use in conjunction with preoperative CT scanning for all vertebral levels. The same is true for bilateral placement at C7 but not at C3-C6. A prospective study to evaluate the long-term outcomes of translaminar fixation at all vertebral levels is currently underway.
    Spine 02/2012; 37(12):E745-51. · 2.08 Impact Factor
  • Article: Lateral Extracavitary, Costotransversectomy, and Transthoracic Thoracotomy Approaches to the Thoracic Spine: Review of Techniques and Complications.
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    ABSTRACT: STUDY DESIGN:: Systematic review. OBJECTIVE:: The authors review complications, as reported in the literature, associated with ventral and posterolateral approaches to the thoracic spine. SUMMARY OF BACKGROUND:: The lateral extracavitary, costotransversectomy, and transthoracic thoracotomy techniques allow surgeons to access the ventral thoracic spine for a wide range of spinal disorders including tumor, degeneration, trauma, and infection. Although the transthoracic thoracotomy has been used traditionally to reach the ventral thoracic spine when access to the vertebral body is required, modifications to the various dorsal approaches have enabled surgeons to achieve goals of decompression, reconstruction, and stabilization through a single approach. METHODS:: A systematic Medline search from 1991 to 2011 was performed to identify series reporting clinical data related to these surgical approaches. The morbidity associated with each approach is reviewed and strategies for complications avoidance are discussed. RESULTS:: Four thousand six hundred seventy-seven articles that assessed outcomes of the approaches to the thoracic spine were identified; of these 31 studies that consisted of 774 patients were selected for inclusion. A mean complication rate of 39%, 17%, and 15% for thoracotomy, lateral extracavitary, and costotransversectomy, respectively, was determined. The thoracotomy approach had the highest reoperation (3.5%) and mortality rates (1.5%). The specific complications and neurological outcomes were categorized. CONCLUSIONS:: Outcomes of the surgical approaches to the thoracic spine have been reported with great detail in the literature. There are limited studies comparing the respective advantages and disadvantages and the differences in technique and outcome between these approaches. The present review suggests that in contrast to the historical experience of the laminectomy for thoracic spine disorders, these alternative approaches are safe and rarely associated with neurological deterioration. The differences between these approaches are based on their complication profiles. A thorough understanding of the regional anatomy will help avoid approach-related complications.
    Journal of spinal disorders & techniques 12/2011; · 1.21 Impact Factor
  • Article: Circumferential Cervical Surgery : To Stage or Not to Stage?
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    ABSTRACT: STUDY DESIGN:: Retrospective review. OBJECTIVE:: The objective of the study was to determine the morbidity and mortality rate associated with same day versus staged cervical circumferential approach. SUMMARY OF BACKGROUND DATA:: A combined approach to the cervical spine is often indicated for complex cervical pathologies. Previous studies suggested superior results associated with same day combined surgery for thoracolumbar patients. This study examines the usefulness of p-Physiological and Operative Severity Score for enumeration of Morbidity and Mortality (POSSUM), an estimated mortality risk assessment for cervical spine patients and will compare same day surgery to staged procedures. METHODS:: This is a retrospective chart review including patients who underwent ventral and dorsal approach within 2 weeks. Estimated mortality was calculated using p-POSSUM. The cohort was divided into same day surgery group and staged group. Risk factors were compared between groups. Mean p-POSSUM was calculated and compared with the actual mortality rate. Univariate analysis was used to compare the risk factors between groups and the groups' outcomes. Multivariable analysis was used to adjust for risk factor differences when comparing group outcomes. RESULTS:: One hundred thirty-five patients were included, 106 patients were in the same day surgery group whereas 29 patients were in the staged group. Mean p-POSSUM was 2.8% predicted mortality with a 95% confidence interval of 1.6% to 4.1%. The actual mortality rate was 3.7%. The groups did not vary in most risk factors assessed. Univariate analysis demonstrated a statistically significantly higher rate of major complications (0.62 vs. 0.34, P=0.0369), infection (41.4% vs. 9.4%, P<0.0001), and length of hospital stay (9.3 vs. 6.8 d, P=0.0120) in the staged group. Multivariable analysis demonstrated significantly higher infection rate in the staged group. CONCLUSIONS:: P-POSSUM mortality estimate may serve as a useful and valid tool for spine surgery studies. Staged combined cervical surgery harbors a higher complication rate and may be associated with lengthier hospitalization.
    Journal of spinal disorders & techniques 11/2011; · 1.21 Impact Factor
  • Article: Oncomodulin affords limited regeneration to injured sensory axons in vitro and in vivo.
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    ABSTRACT: Oncomodulin, an ~12 kDa Ca(2+)-binding protein secreted from activated macrophages, has been shown to promote axonal regeneration from retinal ganglion cells (RGCs) following optic nerve injury. However, to date, the axonal growth-promoting capacity of oncomodulin in other models of 'regenerative failure' has not been evaluated. We assessed the capability of preconditioning treatment with oncomodulin to promote sensory axonal regeneration in an in vitro spot model of regenerative failure, and across the dorsal root zone (DREZ) after root crush injury. Neither the direct exposure of adult rat DRGs to oncomodulin, nor preconditioning of DRGs by intraganglionic injection of oncomodulin, stimulated axonal outgrowth in the in vitro proteoglycan spot gradient assay. However, direct exposure of unconditioned DRGs to both oncomodulin and db-cAMP in vitro, as well as preconditioning of DRGs with the combined treatment in vivo, resulted in significant, albeit modest, neurite extension across the inhibitory proteoglycan barrier. We next quantified axon regeneration through the C8 DREZ in adult rats after oncomodulin and/or db-cAMP preconditioning and chondroitinase (ChABC) injection into the DREZ immediately following a root crush injury. Axonal regeneration across the DREZ was not observed in control animals, or after injection of ChABC-alone. Treatment with oncomodulin- or db-cAMP-alone resulted in extremely sparse regeneration. However, significant, but meager, sensory axon regeneration across the DREZ was observed using the oncomodulin/ db-cAMP combination (p<0.001), supporting findings from previous studies suggesting that cAMP is necessary for the growth-promoting effects of oncomodulin. Although our results support a role for oncomodulin in macrophage-induced axonal regeneration, the effects of oncomodulin/db-cAMP on sensory regeneration were extremely limited in comparison to previous studies in the same injury model using zymosan.
    Experimental Neurology 11/2011; 233(2):708-16. · 4.70 Impact Factor
  • Article: Direct lateral approach to pathology at the craniocervical junction: a technical note.
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    ABSTRACT: Approaches to the foramen magnum and upper cervical spine traditionally include the posterior midline, far lateral, and endoscopic endonasal approaches. The far lateral approach is a well-established technique for the removal of pathology ventrolateral to the brainstem and the craniocervical junction, but it may be too extensive for lesions limited to areas far from the midline. To present an alternative to the commonly used approaches to the foramen magnum and upper cervical. We used an approach directly overlying ventral or lateral pathology. Two cases are presented in which the direct lateral approach followed by an occipitocervical fusion was successfully performed. This approach can be considered for patients in whom a ventral decompression is necessary but an endoscopic endonasal approach is undesirable or when a ventral, lateral, and ventrolateral resection of tumor, pannus, or infection is required.
    Neurosurgery 11/2011; 70(2 Suppl Operative):202-8. · 2.79 Impact Factor
  • Article: Novel reduction technique for thoracolumbar fracture-dislocations.
    Timothy A Moore, Michael P Steinmetz, Paul A Anderson
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    ABSTRACT: Thoracolumbar fracture-dislocations are devastating injuries. They usually require surgical reduction and stabilization. The authors present a novel technique for reducing these injuries that is predictable and reproducible.
    Journal of neurosurgery. Spine 09/2011; 15(6):675-7. · 1.61 Impact Factor
  • Source
    Chapter: Biomechanics of the Craniovertebral Junction
    09/2011; , ISBN: 978-953-307-969-1
  • Article: Radiation exposure to the surgeon during percutaneous pedicle screw placement.
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    ABSTRACT: In-vitro radiation exposure study. To determine the radiation exposure to the eyes, extremities, and deep tissue during percutaneous pedicle screw placement. Image-guided minimally invasive spinal surgery is typically performed with the use of fluoroscopy, exposing the surgeon and patient to ionizing radiation. The radiation dose to the surgeon has not been reported and risk to the surgeon performing this procedure over the long term is uncertain. Percutaneous pedicle screws were placed in a cadaveric specimen from L2-S1 bilaterally using a cannulated pedicle screw system. Two fluoroscopes were used in the anteroposterior and lateral planes. The surgeon wore a thermolucent dosimeter ring on the right hand and badge over the left chest beneath the lead apron. Complete surgical time was recorded and a computed tomography scan was performed to assess screw placement. Radiation exposure was measured for total time of fluoroscopy use; average exposure per screw, surgical level, and dose to the eyes was calculated. This data was used to define the safety of percutaneous pedicle screw placement. Total fluoroscope time for placement of 10 percutaneous pedicle screws was 4 minutes 56 seconds (29 s per screw). The protected dosimeter recorded less than the reportable dose. The ring dosimeter recorded 103 mREM, or 10.3 mREM per screw placed. All screws were within the bone confines with acceptable trajectory. Exposure to the eyes was 2.35 mREM per screw. On the basis of this data, percutaneous pedicle screw placement seems to be safe. A surgeon would exceed occupational exposure limit for the eyes and extremities by placing 4854 and 6396 screws percutaneously, respectively. Lead protected against radiation exposure during screw placement. The "hands-off" technique used in this study is recommended to minimize radiation exposure. Lead aprons, thyroid shields, and leaded glasses are recommended for this procedure.
    Journal of spinal disorders & techniques 06/2011; 24(4):264-7. · 1.21 Impact Factor
  • Article: The unusual response of serotonergic neurons after CNS Injury: lack of axonal dieback and enhanced sprouting within the inhibitory environment of the glial scar.
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    ABSTRACT: Serotonergic neurons possess an enhanced ability to regenerate or sprout after many types of injury. To understand the mechanisms that underlie their unusual properties, we used a combinatorial approach comparing the behavior of serotonergic and cortical axon tips over time in the same injury environment in vivo and to growth-promoting or growth-inhibitory substrates in vitro. After a thermocoagulatory lesion in the rat frontoparietal cortex, callosal axons become dystrophic and die back. Serotonergic axons, however, persist within the lesion edge. At the third week post-injury, 5-HT+ axons sprout robustly. The lesion environment contains both growth-inhibitory chondroitin sulfate proteoglycans (CSPGs) and growth-promoting laminin. Transgenic mouse serotonergic neurons specifically labeled by enhanced yellow fluorescent protein under control of the Pet-1 promoter/enhancer or cortical neurons were cultured on low amounts of laminin with or without relatively high concentrations of the CSPG aggrecan. Serotonergic neurons extended considerably longer neurites than did cortical neurons on low laminin and exhibited a remarkably more active growth cone on low laminin plus aggrecan during time-lapse imaging than did cortical neurons. Chondroitinase ABC treatment of laminin/CSPG substrates resulted in significantly longer serotonergic but not cortical neurite lengths. This increased ability of serotonergic neurons to robustly grow on high amounts of CSPG may be partially due to significantly higher amounts of growth-associated protein-43 and/or β1 integrin than cortical neurons. Blocking β1 integrin decreased serotonergic and cortical outgrowth on laminin. Determining the mechanism by which serotonergic fibers persist and sprout after lesion could lead to therapeutic strategies for both stroke and spinal cord injury.
    Journal of Neuroscience 04/2011; 31(15):5605-16. · 7.11 Impact Factor
  • Article: Dorsal versus ventral surgery for cervical ossification of the posterior longitudinal ligament: considerations for approach selection and review of surgical outcomes.
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    ABSTRACT: Ossification of the posterior longitudinal ligament is a common cause of radiculopathy and myelopathy that often requires surgery to achieve decompression of the neural elements. With the evolution of surgical technique and a greater understanding of the biomechanics of cervical deformity, the criteria for selecting one approach over the other has been the subject of increased study and remains controversial. Ventral approaches typically consist of variations of the cervical corpectomy, whereas dorsal approaches include a wide range of techniques including laminoplasty, laminectomy, and laminectomy with instrumented fusion. Herein, the features and limitations of these approaches are reviewed with an emphasis on complications and outcomes.
    Neurosurgical FOCUS 03/2011; 30(3):E8. · 2.87 Impact Factor
  • Article: The utility of repeated postoperative radiographs after lumbar instrumented fusion for degenerative lumbar spine.
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    ABSTRACT: Retrospective chart review. To assess the impact that routine postoperative radiographs have in clinical outcome and clinical decision-making. No standard exists that outlines how often and when radiographs should be taken after lumbar fusion. Routine postoperative radiographs can be a source of inconvenience and cost to patients, radiation exposure, and possibly, confounding information. The patients who underwent a single or multilevel lumbar instrumented fusion were investigated. At each time-point after surgery, it was noted if they demonstrated new symptoms or clinical deterioration. The Fisher exact test was used to analyze the categorical data. Sixty-three patients (25 males and 38 females) were identified with a mean age of 52 years (range, 20-87). Plain radiographs were taken at 269 visits including all time-points. In 17 (6.3%) visits, abnormal findings were found in 13 patients, including suspected pseudoarthrosis on radiographs (n = 10) and adjacent segment disease on radiographs (n = 3). They were found during 11 of 50 visits (22%) in the patients with new symptoms or clinical deterioration and during 6 of 219 visits (2.7%) in the asymptomatic patients. The probability of an abnormal finding was significantly lower in the asymptomatic patients (P < 0.001). Before the 6-month follow-up, abnormal findings were found in 1 of 111 visits (0.9%) and in 16 of 158 visits (10%) at the 6-month follow-up or later. The probability of an abnormal finding was significantly lower before the 6-month follow-up (P < 0.001). In six of the seven symptomatic patients (86%) with suspected pseudoarthrosis on radiographs, pseudoarthrosis was initially suspected between 6 and 12 months after surgery. This study suggests that plain radiographs should be performed as indicated clinically rather than routinely after instrumented lumbar fusion. The vast majority of asymptomatic patients do not require routine postoperative radiographs.
    Spine 02/2011; 36(23):1955-60. · 2.08 Impact Factor
  • Article: The state of lumbar fusion extenders.
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    ABSTRACT: Review of literature. To evaluate the available literature supporting the use of lumbar fusion extenders in clinical practice. Because of the morbidity associated with the harvest of autologous iliac crest bone grafts, the search for lumber fusion extenders and replacements has accelerated. Many formulations of lumbar fusion extenders have been developed, and it is essential to evaluate clinical literature and available outcome metrics of these extenders. A review of English-language literature was performed between 1990 and January of 2010 for all literature presenting clinical outcomes of lumbar fusion extenders. After controlling for inclusion and exclusion criteria and assigning levels of evidence, 19 clinical studies were fully reviewed including those for demineralized bone matrix, recombinant human bone morphogenetic protein 2 (rhBMP-2), β-tricalcium phosphate, and calcium sulfate. The most extensively studied of the lumbar fusion extenders is β-tricalcium phosphate, especially with regard to its use in adolescent scoliosis correction. The use of rhBMP-2 and demineralized bone matrix is supported only by two and three clinical studies, respectively. Calcium sulfate and other miscellaneous extenders are not conclusively or consistently supported by available clinical studies. Calcium phosphate is the most supported of the lumbar fusion extenders. rhBMP-2 and demineralized bone matrix are supported by smaller bodies of evidence. These formulations are supported by these initial studies but in some cases need to be better examined with regard to side effect profiles.
    Spine 02/2011; 36(20):E1328-34. · 2.08 Impact Factor

Institutions

  • 2006–2013
    • Cleveland Clinic
      • • Center for Spine Health
      • • Department of Neurosurgery
      Cleveland, OH, USA
  • 2012
    • Dent Neurologic Institute
      Buffalo, NY, USA
    • University of Michigan
      • Department of Orthopaedic Surgery
      Ann Arbor, MI, USA
    • Hospital of the University of Pennsylvania
      Philadelphia, PA, USA
  • 2011
    • Ross University, School of Medicine
      Los Angeles, CA, USA
  • 2004–2011
    • Case Western Reserve University
      • • Division of Hospital Medicine (MetroHealth Medical Center)
      • • Department of Neurosciences
      Cleveland, OH, USA
  • 2008–2010
    • Barrow Neurological Institute
      • Department of Neurosurgery
      Phoenix, AZ, USA
  • 2009
    • University of Wisconsin, Madison
      • Department of Neurological Surgery
      Madison, MS, USA