Neurosurgery
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An understanding of the regional anatomy and specific biomechanics of the craniovertebral junction is relevant to the specific diseases that affect the region as well as instrumentation of the occiput, atlas, and axis. This article reviews the bony, ligamentous, and vascular anatomy of the region, in relation to the posterior surgical approach to this anatomically unique segment of the cervical spine. ⋯ Basic principles of instrumentation of the region are also reviewed. The kinematics of the region as they pertain to the anatomic discussion are reviewed and discussed.
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Os odontoideum is an independent ossicle of variable size with smooth circumferential cortical margins separated from the foreshortened odontoid peg. The etiology of os odontoideum remains controversial, but there is now emerging consensus on the traumatic etiology of os odontoideum rather than a congenital source. ⋯ There is a role for conservative treatment of an asymptomatic incidentally found, radiologically stable, and noncompressive os odontoideum. Conversely, surgery has a definite role in symptomatic cases. The main method of surgical treatment today is posterior decompression after reduction and fusion via independent C1 and C2 instrumentation. Irreducible, persistent anterior compression from os odontoideum can be approached by a transoral route with good results in experienced hands.
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Multicenter Study Clinical Trial
Pericranial flap for endoscopic anterior skull-base reconstruction: clinical outcomes and radioanatomic analysis of preoperative planning.
One of the major challenges of cranial base surgery is reconstruction of the dural defect and prevention of postoperative cerebrospinal fluid (CSF) fistula. The introduction of endoscopic techniques and an endonasal approach to the ventral skull base has created new challenges for reconstruction. ⋯ The PCF provides an option for endonasal reconstruction of cranial base defects and can be harvested endoscopically. Pre-operative radiographic evaluation may guide surgical planning. There is minimal donor site morbidity, and the flap provides enough surface area to cover the entire ventral skull base.
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The transoral approach provides the most direct exposure to extradural lesions of the ventral craniovertebral junction. Lesions that extend beyond the exposure provided by the standard transoral approach require an extended transoral modification. The exposure can be expanded in the sagittal and axial planes by adding mandibulotomy, mandibuloglossotomy, palatotomy, and transmaxillary approaches to the standard transoral approach. Extended transoral approaches increase the surgical complexity and the risk of cosmetic and functional complications. Until recently, selection of an extended approach has been arbitrary and dependent on the surgeon's familiarity with the surgical approach. ⋯ Surgical decisions can be based on comprehensive preoperative evaluation of anatomy, pathology, and radiographic studies to maximize exposure while minimizing complications.
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Transarticular screw (TAS) fixation is our preferred method for stable internal fixation of the atlantoaxial joint because of its excellent outcomes, versatility, and cost-effectiveness. ⋯ The placement of TASs is safe and effective for stabilizing the atlantoaxial articulation. Refinements in technique, such as 3-dimensional stereotactic workstation for trajectory planning, have reduced the rate of serious complications. Clinical outcomes are excellent, with nearly 100% of patients achieving stable bony union.