Journal of neurosurgery. Spine
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Stabilization of the craniovertebral junction (CVJ) by using lateral masses requires extensive dissection. The vertebral artery (VA) is commonly anomalous in patients with congenital CVJ anomaly. Such a vessel is likely to be injured during dissection or screw placement. In this study the authors discuss the importance of preoperative evaluation and certain intraoperative steps that reduce the chances of injury to such vessels. ⋯ Preoperative 3D CT angiography is a highly useful method of imaging the artery in patients with CVJ anomaly. It helps in identifying the anomalous VA or its branch and its relationship to the C1-2 facets. The normal side should be surgically treated and distracted first because this helps in opening the abnormal side, aiding in dissection. In the posterior approach the C-2 nerve root is always encountered before the anomalous vessel. The defined vascular anatomy helps in choosing the type of screw. The vessel should be mobilized so as to aid the drilling of facets and the placement of screws and spacers under vision, avoiding its injury (direct or indirect) or compression. With these steps, C1-2 (short segment) rigid fusion can be achieved despite the presence of anomalous VA.
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Although multimodal intraoperative spinal cord monitoring provides greater accuracy, transcranial electrical stimulation motor evoked potential (TcMEP) monitoring became the gold standard for intraoperative spinal cord monitoring. However, there is no definite alarm point for TcMEPs because a multicenter study is lacking. Thus, based on their experience with 48 true-positive cases (that is, a decrease in potentials followed by a new neurological motor deficit postoperatively) encountered between 2007 and 2009, the authors set a 70% decrease in amplitude as the alarm point for TcMEPs. ⋯ This study is the first prospective multicenter study to investigate the alarm point of TcMEPs. The authors recommend the designation of an alarm point of a 70% decrease in amplitude for routine spinal cord monitoring, particularly during surgery for spinal deformity, OPLL, and extramedullary spinal cord tumor.
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Observational Study
Prospective observational study of acute postlumbar laminectomy MRI.
Patients who develop a lower-extremity neurological deficit after lumbar laminectomy present a diagnostic dilemma. In the setting of a neurological deficit, some surgeons use MRI to evaluate for symptomatic compression of the thecal sac. The authors conducted a prospective observational cohort study in patients undergoing open lumbar laminectomy for neurogenic claudication to document the MRI appearance of the postlaminectomy spine and to determine changes in thecal sac diameter caused by the accumulation of epidural fluid. ⋯ Immediately after lumbar laminectomy, the appearance of the thecal sac on MRI can vary widely. In most patients the thecal sac diameter increases after laminectomy despite the presence of epidural blood. In this observational cohort, a reduction in thecal diameter caused by epidural fluid did not correlate with motor function. Results in the small subset of patients where the canal diameter decreased due to epidural fluid compression of the thecal sac raises the question of the utility of immediate postoperative MRI.
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The Estimation of Physiological Ability and Surgical Stress (E-PASS) and Physiological and Operative Severity Score for the enUmeration of Mortality and Morbidity (POSSUM) systems are surgical risk scoring systems that take into account both the patient's preoperative condition and intraoperative variables. While they predict postoperative morbidity and mortality rates for several types of surgery, spinal surgeries are currently not included. The authors assessed the usefulness of E-PASS and POSSUM algorithms and compared the predictive ability of both systems in patients with spinal disorders considered for surgery. ⋯ As E-PASS predicted morbidity more correctly than POSSUM, it is useful for estimating the postoperative risk of patients considered for spinal surgery.
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Renal cell carcinoma (RCC) frequently metastasizes to the spine, and the prognosis can be quite variable. Surgical removal of the tumor with spinal reconstruction has been a mainstay of palliative treatment. The ability to predict prognosis is valuable when determining the role and magnitude of surgical intervention in cancer patients. To better identify factors affecting survival in patients undergoing surgery for spinal metastasis from RCC, the authors undertook a retrospective analysis of a large patient cohort at a tertiary care cancer center. ⋯ The authors identified several factors influencing survival after spine surgery for metastatic spinal RCC, including grade of the original nephrectomy specimen, activity of the systemic disease, and neurological status at the time of surgery. These clinical features may help to identify patients who may benefit from aggressive surgical intervention.