Browsing by Subject "Spinal Canal"

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    ItemOpen Access
    Evaluation of monoenergetic imaging to reduce metallic instrumentation artifacts in computed tomography of the cervical spine.
    (Journal of neurosurgery. Spine, 2015-01) Komlosi, Peter; Grady, Deborah; Smith, Justin S; Shaffrey, Christopher I; Goode, Allen R; Judy, Patricia G; Shaffrey, Mark; Wintermark, Max

    Object

    Monoenergetic imaging with dual-energy CT has been proposed to reduce metallic artifacts in comparison with conventional polychromatic CT. The purpose of this study is to systematically evaluate and define the optimal dual-energy CT imaging parameters for specific cervical spinal implant alloy compositions.

    Methods

    Spinal fixation rods of cobalt-chromium or titanium alloy inserted into the cervical spine section of an Alderson Rando anthropomorphic phantom were imaged ex vivo with fast-kilovoltage switching CT at 80 and 140 peak kV. The collimation width and field of view were varied between 20 and 40 mm and medium to large, respectively. Extrapolated monoenergetic images were generated at 70, 90, 110, and 130 kiloelectron volts (keV). The standard deviation of voxel intensities along a circular line profile around the spine was used as an index of the magnitude of metallic artifact.

    Results

    The metallic artifact was more conspicuous around the fixation rods made of cobalt-chromium than those of titanium alloy. The magnitude of metallic artifact seen with titanium fixation rods was minimized at monoenergies of 90 keV and higher, using a collimation width of 20 mm and large field of view. The magnitude of metallic artifact with cobalt-chromium fixation rods was minimized at monoenergies of 110 keV and higher; collimation width or field of view had no effect.

    Conclusions

    Optimization of acquisition settings used with monoenergetic CT studies might yield reduced metallic artifacts.
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    ItemOpen Access
    Frequency, timing, and predictors of neurological dysfunction in the nonmyelopathic patient with cervical spinal cord compression, canal stenosis, and/or ossification of the posterior longitudinal ligament.
    (Spine, 2013-10) Wilson, Jefferson R; Barry, Sean; Fischer, Dena J; Skelly, Andrea C; Arnold, Paul M; Riew, K Daniel; Shaffrey, Christopher I; Traynelis, Vincent C; Fehlings, Michael G

    Study design

    Systematic review and survey.

    Objective

    To perform an evidence synthesis of the literature and obtain information from the global spine care community assessing the frequency, timing, and predictors of symptom development in patients with radiographical evidence of cervical spinal cord compression, spinal canal narrowing, and/or ossification of posterior longitudinal ligament (OPLL) but no symptoms of myelopathy.

    Summary of background data

    Evidence for a marker to predict symptom development remains sparse, and there is controversy surrounding the management of asymptomatic patients.

    Methods

    We conducted a systematic review of the English language literature and an international survey of spine surgeons to answer the following key questions in patients with radiographical evidence of cervical spinal cord compression, spinal canal narrowing, and/or OPLL but no symptoms of myelopathy: (1) What are the frequency and timing of symptom development? (2) What are the clinical, radiographical, and electrophysiological predictors of symptom development? (3) What clinical and/or radiographical features influence treatment decisions based on an international survey of spine care professionals?

    Results

    The initial literature search yielded 388 citations. Applying the inclusion/exclusion criteria narrowed this to 5 articles. Two of these dealt with the same population. For patients with spinal cord compression secondary to spondylosis, one study reported the frequency of myelopathy development to be 22.6%. The presence of symptomatic radiculopathy, cervical cord hyperintensity on magnetic resonance imaging, and prolonged somatosensory- and motor-evoked potentials were reported in one study as significant independent predictors of myelopathy development. In contrast, the lack of magnetic resonance imaging hyperintensity was found to be a positive predictor of early myelopathy development (≤ 12-mo follow-up). For subjects with OPLL, frequency of myelopathy development was reported in 3 articles and ranged from 0.0% to 61.5% of subjects. One of these studies reported canal stenosis of 60% or more, lateral deviated OPLL, and increased cervical range of motion as significant predictors of myelopathy development. In a survey of 774 spine surgeons, the majority deemed the presence of clinically symptomatic radiculopathy to predict progression to myelopathy in nonmyelopathic patients with cervical stenosis. Survey responses pertaining to 3 patient case vignettes are also presented and discussed in the context of the current literature.

    Conclusion

    On the basis of these results, we provide a series of evidence-based recommendations related to the frequency, timing, and predictors of myelopathy development in asymptomatic patients with cervical stenosis secondary to spondylosis or OPLL. Future prospective studies are required to refine our understanding of this topic. EVIDENCE-BASED CLINICAL RECOMMENDATIONS:

    Recommendation

    Patients with cervical canal stenosis and cord compression secondary to spondylosis, without clinical evidence of myelopathy, and who present with clinical or electrophysiological evidence of cervical radicular dysfunction or central conduction deficits seem to be at higher risk for developing myelopathy and should be counseled to consider surgical treatment.

    Overall strength of evidence

    Moderate.

    Strength of recommendation

    Strong. SUMMARY STATEMENTS: STATEMENT 1: On the basis of the current literature, for patients with cervical canal stenosis and cord compression secondary to spondylosis, without clinical evidence of myelopathy, approximately 8% at 1-year follow-up and 23% at a median of 44-months follow-up develop clinical evidence of myelopathy. STATEMENT 2: For patients with cervical canal stenosis and cord compression secondary to spondylosis, without clinical evidence of myelopathy, the absence of magnetic resonance imaging intramedullary T2 hyperintensity has been shown to predict early myelopathy development (<12-mo follow-up) and the presence of such signal has been shown to predict late myelopathy development (mean 44-mo follow-up). In light of this discrepancy, no definite recommendation can be made surrounding the utility of this finding in predicting myelopathy development. STATEMENT 3: For patients with OPLL but without myelopathy, no recommendation can be made regarding the incidence or predictors of progression to myelopathy.