World Neurosurg
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Review
Retro-odontoid Pseudotumor Without Radiological Atlanto-axial Instability: a Systematic Review.
Retro-odontoid pseudotumor (RP) can be caused by several diseases, especially rheumatoid arthritis, and is usually associated with the presence of atlantoaxial instability. On the other hand, a different group of patients have been identified in whom RP is observed without radiologic findings of atlantoaxial instability. The pathophysiology, clinical characteristics, and prognosis of this latter group of patients are not well described in the literature. ⋯ The results of this review show that RPWRI has different causes such as hypermobility, deposition of substances, and perhaps disc herniation. Depending on the cause of RPWRI, the pathophysiologic mechanism is different. Treatment should be tailored based on the primary cause of RP and the degree of compression of the cervicomedullary junction. Different degrees of improvement are usually observed after surgical treatment in these patients regardless of the treatment used, but a higher rate of mass regression was observed in those patients in whom the atlantoaxial joint was stabilized.
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As minimally invasive spine surgery evolves, spine surgeons increasingly rely on advanced intraoperative computed tomography (iCT). iCT provides rapid acquisition of high-resolution images, reduces radiation exposure, improves surgical accuracy, and decreases operative time. However, all iCT systems currently available pose a patient safety risk as their physical space requirements limit patient access in the event of an emergency, particularly when patients are in the prone position. After a near-cardiac arrest at our institution during posterior cervical spine surgery, it was apparent that the presence of the iCT complicated the ability to rapidly reposition the patient in order to provide appropriate resuscitation. ⋯ The development and rehearsal of an emergency plan of action greatly facilitated the timely responsiveness of the neurosurgical OR team during a simulated cardiac arrest and was an effective way to identify and address key logistical issues regarding the use of an iCT system.
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An anomalous vertebral artery is not a deterrent for posterior C1-C2 joint manipulation and reduction of atlantoaxial dislocation (AAD). However, presence of an incidental aneurysm in the aberrant segment of artery with concurrent AAD adds to the surgical challenge. ⋯ The association of an incidental aneurysm with an anomalous vertebral artery in congenital AAD is unusual. The etiology could be an underlying collagen defect or repeated shearing trauma to the vessel wall due to C1-C2 instability. It would be less risky to proceed with endovascular embolization followed by occipitocervical fusion without opening the joints in case the aneurysm is present on the dominant aberrant V3 segment. Ventral decompression can be supplemented for irreducible AAD. On the contrary, if the aneurysm is present on the nondominant aberrant V3 segment, the C1-2 joint can be opened and manipulated following an initial endovascular treatment of the aneurysm. If the circumstances demand, the nondominant artery can be ligated and sacrificed, although there is a small risk of formation of stump aneurysm.
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The aims of this retrospective cohort study were to 1) identify new alignment risk factors for proximal junctional kyphosis (PJK) in adult spinal deformity (ASD) patients with lower thoracic upper instrumented vertebra (UIV) and 2) determine the effect of junctional tethers on PJK and UIV alignment. ⋯ Junctional tethers significantly reduced PJK in ASD patients with lower thoracic UIV. In tethered patients, PJK was more common with greater postoperative lordosis of the upper lumbar spine and greater UIV angle. This finding suggests potential benefit of tethers to mitigate effects of segmental lumbar and focal UIV malalignment that may occur after deformity surgery.