Factors Associated With C5 Palsy Following Cervical Spine Surgery: A Systematic Review.

Study Design: Systematic review. Objectives: C5 palsy (C5P) is a not uncommon and disabling postoperative complication with a reported incidence varying between 0% and 30%. Among others, one explanation for its occurrence includes foraminal nerve root tethering. Although different risk factors have been reported, controversy about its causation and prevention persists. Inconsistent study findings contribute to the persistent ambiguity leading to an assumption of a multifactorial nature of the underlying C5P pathophysiology. Here, we report the results of a systematic review on C5P with narrow inclusion criteria in the hope of elucidating risk factors for C5P due to a common pathophysiological mechanism. Methods: Electronic databases from inception to March 9, 2019 and references of articles were searched. Narrow inclusion criteria were applied to identify studies investigating demographic, clinical, surgical, and radiographic factors associated with postoperative C5P. Results: Sixteen studies were included after initial screening of 122 studies. Eighty-four risk factors were analyzed; 27 in ≥2 studies and 57 in single studies. The pooled prevalence of C5P was 6.0% (range: 4.2%-24.1%) with no consistent evidence that C5P was associated with demographic, clinical, or specific surgical factors. Of the radiographic factors assessed, specifically decreased foraminal diameter and preoperative cord rotation were identified as risk factors for C5P. Conclusion: Although risk factors for C5P have been reported, ambiguity remains due to potentially multifactorial pathophysiology and study heterogeneity. We found foraminal diameter and cord rotation to be associated with postoperative C5P occurrence in our meta-analysis. These findings support the notion that factors contributing to, and acting synergistically with foraminal stenosis increase the risk of postoperative C5P

Percutaneous Cortical Screw Fixation as a Method for Posterior Spinal Stabilization

Objective Novel minimally invasive surgery (MIS) approaches and instrumentation such as cortical screws (CS) have recently become commonplace for treating spinal disease. CS comparability to pedicle screws (PS) with respect to safety and mechanical stability, however, have yet to be determined. To our knowledge, this is the first report to describe a percutaneous CS fixation technique with subsequent open anatomical dissection and describe its feasibility compared to PS fixation. Methods Fresh frozen cadavers were used for fluoroscopy-guided placement of a total of 20 percutaneous PS and CS. Standard percutaneous PS fixation was performed in cadavers from L1-L5 on one-side followed by CS being placed on the other side. Open anatomical dissection was then performed to confirm placement and compare pedicle breach incidence between PS and CS. Results Both percutaneous PS and CS were easily placed without difficulty. Dissection revealed no breaches of either construct, and as such no statistical comparison was possible. At one-level however, a CS was seen breaching the posterior-third lateral vertebral body (VB) just under the superior end-plate. Two screw threads exposed were visualized well away from any entering and/or exiting foraminal or paraspinal neurovascular structures. Conclusion Here, we report a novel study of percutaneous CS insertion with open cadaveric dissection comparing it to PS, incorporating the advantages of both MIS and CS fixation. Although feasible and technically comparable to PS in this report, further study comparing these two techniques and rigorous patient selection for its application are necessary

Foraminal Ligaments Tether Upper Cervical Nerve Roots: A Potential Cause of Postoperative C5 Palsy.

Background Nerve root tethering upon dorsal spinal cord (SC) migration has been proposed as a potential mechanism for postoperative C5 palsy (C5P). To our knowledge, this is the first study to investigate this relationship by anatomically comparing C5-C6 nerve root translation before and after root untethering by cutting the cervical foraminal ligaments (FL). Objective The aim of this study is to determine if C5 root untethering through FL cutting results in increased root translation. Methods Six cadaveric dissections were performed. Nerve roots were exposed via C4-C6 corpectomies and supraclavicular brachial plexus exposure. Pins were inserted into the C5-C6 roots and adjacent foraminal tubercle. Translation was measured as the distance between pins after the SC was dorsally displaced 5 mm before and after FL cutting. Clinical feasibility of FL release was examined by comparing root translation between standard and extended (complete foraminal decompression) foraminotomies. Translation of root levels before and after FL cutting was compared by two-way repeated measures analysis of variance. Statistical significance was set at 0.05. Results Significantly more nerve root translation was observed if the FL was cut versus not-cut, p = 0.001; no difference was seen between levels, p = 0.33. Performing an extended cervical foraminotomy was technically feasible allowing complete FL release and root untethering, whereas a standard foraminotomy did not. Conclusion FL tether upper cervical nerve roots in their foramina; cutting these ligaments untethers the root and increases translation suggesting they could be harmful in the context of C5P. Further investigation is required examining the value of root untethering in the context of C5P

Management of Acute Traumatic Central Cord Syndrome: A Narrative Review.

Study Design Narrative review. Objectives To provide an updated overview of the management of acute traumatic central cord syndrome (ATCCS). Methods A comprehensive narrative review of the literature was done to identify evidence-based treatment strategies for patients diagnosed with ATCCS. Results ATCCS is the most commonly encountered subtype of incomplete spinal cord injury and is characterized by worse sensory and motor function in the upper extremities compared with the lower extremities. It is most commonly seen in the setting of trauma such as motor vehicles or falls in elderly patients. The operative management of this injury has been historically variable as it can be seen in the setting of mechanical instability or preexisting cervical stenosis alone. While each patient should be evaluated on an individual basis, based on the current literature, the authors' preferred treatment is to perform early decompression and stabilization in patients that have any instability or significant neurologic deficit. Surgical intervention, in the appropriate patient, is associated with an earlier improvement in neurologic status, shorter hospital stay, and shorter intensive care unit stay. Conclusions While there is limited evidence regarding management of ATCCS, in the presence of mechanical instability or ongoing cord compression, surgical management is the treatment of choice. Further research needs to be conducted regarding treatment strategies and patient outcomes

The lexicon of multirod constructs in adult spinal deformity: a concise description of when, why, and how.

The use of multirod constructs in the setting of adult spinal deformity (ASD) began to prevent rod fracture and pseudarthrosis near the site of pedicle subtraction osteotomies (PSOs) and 3-column osteotomies (3COs). However, there has been unclear and inconsistent nomenclature, both clinically and in the literature, for the various techniques of supplemental rod implantation. In this review the authors aim to provide the first succinct lexicon of multirod constructs available for the treatment of ASD, providing a universal nomenclature and definition for each type of supplementary rod. The primary rod of ASD constructs is the longest rod that typically spans from the bottom of the construct to the upper instrumented vertebrae. The secondary rod is shorter than the primary rod, but is connected directly to pedicle screws, albeit fewer of them, and connects to the primary rod via lateral connectors or cross-linkers. Satellite rods are a 4-rod technique in which 2 rods span only the site of a 3CO via pedicle screws at the levels above and below, and are not connected to the primary rod (hence the term satellite ). Accessory rods are connected to the primary rods via side connectors and buttress the primary rod in areas of high rod strain, such as at a 3CO or the lumbosacral junction. Delta rods span the site of a 3CO, typically a PSO, and are not contoured to the newly restored lordosis of the spine, thus buttressing the primary rod above and below a 3CO. The kickstand rod itself functions as an additional means of restoring coronal balance and is secured to a newly placed iliac screw on the side of truncal shift and connected to the primary rod; distracting against the kickstand then helps to correct the concavity of a coronal curve. The use of multirod constructs has dramatically increased over the last several years in parallel with the increasing prevalence of ASD correction surgery. However, ambiguity persists both clinically and in the literature regarding the nomenclature of each supplemental rod. This nomenclature of supplemental rods should help unify the lexicon of multirod constructs and generalize their usage in a variety of scientific and clinical scenarios

Use of a tubular retractor for transoral odontoidectomy of upper cervical epidural phlegmon extraction and abscess drainage

Anterior epidural abscess of the superior cervical cord with odontoid osteomyelitis is a rare but potentially devastating condition due to the potential for severe and irreversible neurological injury. Early and aggressive neurosurgical intervention and medical management is usually indicated in cases with symptomatic spinal cord compression and may be associated with superior clinical outcomes. Access to the craniovertebral junction for decompression of the upper cervical cord is complicated by the proximity of critical anatomical structures. The transoral approach is considered to be the standard for treating lesions of the odontoid and anterior epidural space of the superior cervical spine. The use of a tubular retractor for procedures of the craniovertebral junction has been described for several approaches to this region but its use has yet to be described for the transoral approach in a live patient. This report describes the novel use of a tubular retractor for cervicomedullary decompression via transoral odontoidectomy for abscess drainage and phlegmon resection in a patient with progressive cervical myelopathy. The tubular retractor serves to retract the pharyngeal wall flaps and expose the anterior arch of C1, odontoid, and inferior clivus. This variation of the transoral approach eliminates the need for stay sutures for these purposes and may be used for lesions of the odontoid and anterior epidural space of the superior cervical spine.Open Access Article. UA Open Access Publishing Fund.This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

A hierarchical model for the development of cerebral arteriovenous malformations

OBJECTIVE: Cerebral arteriovenous malformations (AVMs) are vascular lesions whose pathogenesis, although not fully elucidated, is likely multifactorial. Recent research investigating vessel development suggests a potential hierarchical model in which capillary sprouts from higher-flow arteries give rise to lower-flow veins. It is possible that an embryologic structural vascular dysgenesis in this hierarchical development heavily contributes to the formation of AVMs. Subsequent genetic second hits may then allow development of a clinically significant cerebral AVM. We review this vascular developmental process and describe a novel proposal for the embryogenesis of AVMs and its implications in relation to recent research on polymorphisms and AVMs. METHODS: A comprehensive literature search was performed using PubMed for recent research relative to cerebral AVMs, embryologic vascular development, and polymorphisms involved in AVM pathology. RESULTS: It has recently been shown that both centrally, in the axial embryo, and peripherally, in the embryonic yolk sac, veins form via capillary sprouting from parent arteries. In developing intracranial vessels, a derangement in this embryonic process may lead to a primitive arteriovenous shunt. After this structural first hit, we suggest that single nucleotide polymorphisms (SNPs) are a major component in allowing AVM growth into symptomatic clinical lesions. CONCLUSIONS: This is a novel theory for the embryologic formation of cerebral AVMs. Hierarchical vessel development, where higher-flow parent arteries give rise to lower-flow veins, provides a potential mechanism for the formation of primitive arteriovenous shunts that, with the influence of polymorphisms, allows AVMs to develop

Use of a tubular retractor for transoral odontoidectomy of upper cervical epidural phlegmon extraction and abscess drainage

Anterior epidural abscess of the superior cervical cord with odontoid osteomyelitis is a rare but potentially devastating condition due to the potential for severe and irreversible neurological injury. Early and aggressive neurosurgical intervention and medical management is usually indicated in cases with symptomatic spinal cord compression and may be associated with superior clinical outcomes. Access to the craniovertebral junction for decompression of the upper cervical cord is complicated by the proximity of critical anatomical structures. The transoral approach is considered to be the standard for treating lesions of the odontoid and anterior epidural space of the superior cervical spine. The use of a tubular retractor for procedures of the craniovertebral junction has been described for several approaches to this region but its use has yet to be described for the transoral approach in a live patient. This report describes the novel use of a tubular retractor for cervicomedullary decompression via transoral odontoidectomy for abscess drainage and phlegmon resection in a patient with progressive cervical myelopathy. The tubular retractor serves to retract the pharyngeal wall flaps and expose the anterior arch of C1, odontoid, and inferior clivus. This variation of the transoral approach eliminates the need for stay sutures for these purposes and may be used for lesions of the odontoid and anterior epidural space of the superior cervical spine. Keywords: Odontoidectomy, Odontoid osteomyelitis, Tubular retractor, Transoral, Epidural abscess, Spin

Mathematically modeling the biological properties of gliomas: A review

Although mathematical modeling is a mainstay for industrial and many scientific studies, such approaches have found little application in neurosurgery. However, the fusion of biological studies and applied mathematics is rapidly changing this environment, especially for cancer research. This review focuses on the exciting potential for mathematical models to provide new avenues for studying the growth of gliomas to practical use. In vitro studies are often used to simulate the effects of specific model parameters that would be difficult in a larger-scale model. With regard to glioma invasive properties, metabolic and vascular attributes can be modeled to gain insight into the infiltrative mechanisms that are attributable to the tumor\u27s aggressive behavior. Morphologically, gliomas show different characteristics that may allow their growth stage and invasive properties to be predicted, and models continue to offer insight about how these attributes are manifested visually. Recent studies have attempted to predict the efficacy of certain treatment modalities and exactly how they should be administered relative to each other. Imaging is also a crucial component in simulating clinically relevant tumors and their influence on the surrounding anatomical structures in the brain