Posterior cervical spine arthrodesis with laminar screws: a report of two cases.
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We performed fixation using laminar screws in 2 patients in whom lateral mass screws, pedicle screws or transarticular screws could not be inserted. One was a 56-year-old woman who had anterior atlantoaxial subluxation (AAS). When a guide wire was inserted using an imaging guide, the hole bled massively. We thought the re-insertion of a guide wire or screw would thus increase the risk of vascular injury, so we used laminar screws. The other case was an 18-year-old man who had a hangman fracture. Preoperative magnetic resonance angiography showed occlusion of the left vertebral artery. A laminar screw was inserted into the patent side (i.e., the right side of C2). Cervical pedicle screws are the most biomechanically stable screws. However, their use carries a high risk of neurovascular complications during screw insertion, because the cervical pedicle is small and is adjacent laterally to the vertebral artery, medially to the spinal cord, and vertically to the nerve roots. Lateral mass screws are also reported to involve a risk of neurovascular injuries. The laminar screw method was thus thought to be useful, since arterial injuries could thus be avoided and it could also be used as a salvage modality for the previous misinsertion. (+info)
Pure endoscopic endonasal odontoidectomy: anatomical study.
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Different disorders may produce irreducible atlanto-axial dislocation with compression of the ventral spinal cord. Among the surgical approaches available for a such condition, the transoral resection of the odontoid process is the most often used. The aim of this anatomical study is to demonstrate the possibility of an anterior cervico-medullary decompression through an endoscopic endonasal approach. Three fresh cadaver heads were used. A modified endonasal endoscopic approach was made in all cases. Endoscopic dissections were performed using a rigid endoscope, 4 mm in diameter, 18 cm in length, with 0 degree lenses. Access to the cranio-vertebral junction was possible using a lower trajectory, when compared to that necessary for the sellar region. The choana is entered and the mucosa of the rhinopharynx is dissected and transposed in the oral cavity in order to expose the cranio-vertebral junction and to obtain a mucosal flap useful for the closure. The anterior arch of the atlas and the odontoid process of C2 are removed, thus exposing the dura mater. The endoscopic endonasal approach could be a valid alternative to the transoral approach for anterior odontoidectomy. (+info)
Acute outcomes of cervical spine injuries in the elderly: atlantaxial vs subaxial injuries.
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BACKGROUND/OBJECTIVE: Recent studies have reported on the outcomes of spinal cord injuries in the elderly. Our aim was to identify acute survival differences between elderly patients with atlantoaxial injuries relative to subaxial injuries at our institution and to determine whether operative treatment is associated with improved survival rates in either population. STUDY DESIGN: Retrospective database review of all traumatic cervical spine injuries in patients at least 65 years of age at a single tertiary care center. METHODS: A total of 193 consecutive patients at least 65 years of age treated at a single tertiary care center over a 12-year period were identified. Initial hospitalization records were reviewed. Patients were divided by anatomic level of injury: atlantoaxial (C1 or C2) and subaxial (C3 or below). Demographics, mechanism, and mortality rates were compared. Each group was further divided by treatment (operative or nonoperative), and inpatient survival rates were compared. RESULTS: Statistically similar survival rates were observed among patients with atlantoaxial and subaxial injuries (P = 0.10). Patients with nonoperatively treated subaxial injuries died at significantly higher rates than did their operatively treated peers (P < 0.05). CONCLUSIONS: In this large comprehensive series of elderly patients with cervical spine injuries, survival rates were comparable regardless of anatomic level of injury. The operative treatment of subaxial injuries was associated with an improved acute survival rate vs nonoperative management. Further prospective study is needed to better assess this relationship. (+info)
Reassessment of the craniocervical junction: normal values on CT.
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BACKGROUND AND PURPOSE: As the standard of care for the evaluation of the cervical spine shifts from plain radiographs to multidetector row CT (MDCT), a re-examination of the normal anatomic relationships of the occipitovertebral articulations is needed. We aimed to define the normal anatomic relationships of craniocervical articulations on MDCT and address any discrepancies with currently accepted ranges of normal on plain radiographs. MATERIALS AND METHODS: A total of 200 patients underwent an MDCT scan of the cervical spine with multiplanar reconstructions (MPR). We measured the basion-axial interval (BAI), basion-dens interval (BDI), Powers ratio, atlantodental interval (ADI), and atlanto-occipital interval (AOI) in each patient. After statistical analysis, we compared these values to previously accepted data on plain radiographs. RESULTS: Ninety-five percent of the population was found to have a BDI less than 8.5 mm compared with 12 mm on data from plain radiographs. The Powers ratio demonstrated no significant difference compared with data obtained by plain radiographs. Ninety-five percent of the population was found to have an ADI less than 2 mm, compared with 3 mm previously accepted. The AOI demonstrated 95% of the population ranged between 0.5 mm and 1.4 mm. The BAI was difficult to reproduce on CT images. CONCLUSION: Normal values for the craniocervical relationships on MDCT are significantly different from the accepted ranges of normal on plain radiographs. We propose these values as normal for the adult population. (+info)
Screw fixation via diploic bone paralleling to occiput table: anatomical analysis of a new technique and report of 11 cases.
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Several types of posterior approaches have been adopted for occipitocervical fusion. Prior to this study, Foerater et al. in 1927 used a fibular strut graft in the site between the occiput and the lower cervical spine to achieve fusion. Since then, various techniques including wrings, Hartshill loop, AO reconstructive plate, and AXIS occipital plate were described and used widely. As far as we know, all these techniques involve the screw placement vertical to the diploic bone; however none has ever addressed the feasibility of screw placement in occiput parallelling to the diploic bone. In our study, 30 dry specimens of human occiputs were measured manually using vernier calipers and protractors. The intradiploic screw was first supposed to be inserted inferiorly to the superior nuchal line (SNL) prominence. The entry point located at the superior edge of the SNL prominence. Afterward, the measurements of extracranial occiput in SNL area on midline and bilateral 15 mm to the midline saggital-cutting planes of the occiput were conducted. The thickness of the occipital bone at the location of SNL prominence, the entry point, the exit point and the screw orientation were measured, respectively. Afterward, 11 patients with craniocervical malformation were treated surgically using this alternative and their X-ray radiographs and CT scans were evaluated postoperatively. The data showed that the occipital at the site of SNL prominence was the thickest. The thickest point was external occipital protuberance (EOP), which was up to 14 mm. The thickness decreased gradually from the site of SNL to the superior border of surgical decompressed area. The actual length of screw channel was about 26 mm. The mean thickness for safe screw insertion ranged from 5.73 to 14.14 mm. A total of 22 intraocciput screws parallel to diploic bone were placed precisely, without injury to the cerebral and inner occipital venous sinus. The results confirm that occiput is available for holding intraocciput screw paralleling to diploic bone. (+info)
Intraoperative monitoring of a patient with craniovertebral junction meningioma.
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Intraoperative monitoring is considered as a useful tool to prevent neurological damage during different neurosurgical procedures. Somatosensory evoked potentials (SEP) allow simultaneous assessment of several cortical and sub cortical centers. In this case presentation, we report intraoperative monitoring of an elderly patient with craniovertebral junction meningioma. Tibial SEP responses were elicited by stimulation of the tibial nerve; the recordings were visually analyzed for the presence of the main peaks P40-N50, peak to peak amplitudes, peak latencies and compared to baseline recordings throughout the procedure. During decompression from the medial aspect of the medulla SEP responses were lost for a brief period of time. Surgeons achieved total tumor removal and the patient left the operating room without any neurological deficit. (+info)
Placement of C2 laminar screws using three-dimensional fluoroscopy-based image guidance.
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The use of C2 laminar screws in posterior cervical fusion is a relatively new technique that provides rigid fixation of the axis with minimal risk to the vertebral artery. The techniques of C2 laminar screw placement described in the literature rely solely on anatomical landmarks to guide screw insertion. The authors report on their experience with placement of C2 laminar screws using three-dimensional (3D) fluoroscopy-based image-guidance in eight patients undergoing posterior cervical fusion. Overall, fifteen C2 laminar screws were placed. There were no complications in any of the patients. Average follow-up was 10 months (range 3-14 months). Postoperative computed tomographic (CT) scanning was available for seven patients allowing evaluation of placement of thirteen C2 laminar screws, all of which were in good position with no spinal canal violation. The intraoperative planning function of the image-guided system allowed for 4-mm diameter screws to be placed in all cases. Using modified Odom's criteria, excellent or good relief of preoperative symptoms was noted in all patients at final follow-up. (+info)
Occipitocervical contoured rod stabilization: does it still have a role amidst the modern stabilization techniques?
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BACKGROUND: The occipitocervical contoured rod (CR) stabilization for use in craniovertebral junction (CVJ) pathologies is an effective and economical technique of posterior fusion (PF). AIMS: The various indications for CR in CVJ pathologies are discussed. SETTINGS AND DESIGN: Retrospective analysis. MATERIALS AND METHODS: Fifty-four patients (mean age: 31.02+/-13.44 years; male: female ratio=5.75:1) who underwent CR stabilization are included. The majority had congenital atlantoaxial dislocation (AAD; n=50); two had CVJ tuberculosis; one each had rheumatoid arthritis and C2-3 listhesis, respectively. The indications for CR fusion in congenital AAD were associated Chiari 1 malformation (C1M) (n=29); occipitalized C1 arch and/or malformed or deficient C1 or C2 posterior elements (n=9); hypermobile AAD (n=2); and, rotatory AAD (n=3). Contoured rod as a revision procedure was also performed in seven patients. Most patients were in poor grade (18 in Grade III [partial dependence for daily needs] and 15 in Grade IV [total dependence]); 15 patients were in Grade II [independent except for minor deficits] and six in Grade I [no weakness except hyperreflexia or neck pain]. RESULTS: Twenty-four patients improved, 18 stabilized and six deteriorated at a mean follow-up (FU) of 17.78+/-19.75 (2-84) months. Six patients were lost to FU. In 37 patients with a FU of at least three months, stability and bony union could be assessed. Thirty-one of them achieved a bony fusion/stable construct. CONCLUSIONS: Contoured rod is especially useful for PF in cases of congenital AAD with coexisting CIM, cervical scoliosis, sub-axial instability and/or asymmetrical facet joints. In acquired pathologies with three-column instability, inclusion of joints one level above the affected one by using CR, especially enhances stability. (+info)