Study of the Anatomical Variations of Vertebral Artery in C2 Vertebra With Magnetic Resonance Imaging and Its Application in the C1–C2 Transarticular Screw Fixation

Lau, Sun Wing; Sun, Lun Kit; Lai, Ronald; Luk, Man Sze Karen; Ng, Yuet Sun; Wong, N M; Lau, P Y

doi:10.1097/brs.0b013e3181bb4f21

Cited by 22 publications

(18 citation statements)

References 21 publications

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“…From the biomechanical viewpoint, techniques using screws are superior to the wiring technique but have the disadvantage of the risk of injury to the vertebral artery, spinal cord and roots. 1,4-7 …”

Section: Discussionmentioning

confidence: 99%

“…One of the main aspects in relation to the anatomy of C1-C2 is the location of the vertebral artery, 1 which runs through the transverse foramen of C1, looping on both sides in the posteromedial direction up to its point of entry in the occipital foramen. This structure, therefore, is at risk during the passage of screws in both vertebrae.…”

Section: Introductionmentioning

confidence: 99%

“…5 Both techniques, from the biomechanical viewpoint, are superior to the wiring technique and also involve the insertion of screws in the pedicles or through the pars interarticularis of C2, posing a significant risk for the vertebral artery, as hemorrhages, neurological sequelae and even death could occur. 1,4-7 …”

Section: Introductionmentioning

confidence: 99%

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Análise tomográfica dos parâmetros anatômicos do áxis de crianças

et al. 2012

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ObjectiveTo carry out an anatomical study of the axis with the use of computed tomography (CT) in children aged from two to ten years, measuring the lamina angle, lamina and pedicle length and thickness, and lateral mass length.MethodsSixty-four CTs were studied from patients aged 24 to 120 months old, of both sexes and without any cervical anomaly. The measurements obtained were correlated with the data on age and sex of the patients. Statistical analysis was performed using the Students "t" tests.ResultsWe found that within the age range 24-48 months, 5.5% of the lamina and 8.3% of the pedicles had thicknesses of less than 3.5mm, which is the minimum thickness needed for insertion of the screw. Between 49 and 120 months, there were no lamina thicknesses of less than 3.5mm, and 1.2% of the pedicle thicknesses were less than 3.5mm values. Neither of the age groups had any lamina and pedicle lengths of less than 12mm, or lateral mass lengths greater than 12mm.ConclusionThe analysis of the data obtained demonstrates that most of the time, is possible to use a 3.5mm pedicle screw in the laminas and pedicles of the axis in children. Level of Evidence: II, Development of diagnostic criteria in consecutive patients.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Análise tomográfica dos parâmetros anatômicos do áxis de crianças

et al. 2012

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“…The Harms technique [6] uses polyaxial screws applied to the lateral mass of the atlas and the pedicles of the axis connected via bilateral rods. Both techniques are technically demanding and carry a risk of vertebral artery injury, especially in aberrant courses, which occur in up to 23% of all cases [11]. The surgeon is manually limited by the small dimension of the C2 pedicle.…”

Section: Introductionmentioning

confidence: 99%

Translaminar screws of the axis—an alternative technique for rigid screw fixation in upper cervical spine instability

Meyer

Kretschmer

et al. 2011

Neurosurg Rev

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C2 pedicle screws or transarticular atlantoaxial screws are technically demanding and carry an increased risk of vertebral artery injury. In up to 20% of cases, pedicle and transarticular screw placement is not possible due to a high-riding vertebral artery or very small C2 pedicles in addition to other anatomical variations. Translaminar screws have been reported to rigidly capture posterior elements of C2 and therefore appear to be a suitable alternative. We present our first experiences and clinical results with this new method in two neurosurgical spine centers. Twenty-seven adult patients were treated between 2007 and 2010 in two neurosurgical spine departments with C2 translaminar screw fixation for upper cervical spine instability of various origins (e.g., trauma, tumor, dens pseudarthrosis). Eight patients were men and 19 were women. Mean age was 68.9 years. In most cases, translaminar screws were used because of contraindications for pedicle or transarticular screws as a salvage technique. All patients were clinically assessed and had CT scans postoperatively to verify correct screw placement. Follow-up was performed with reexamination on an ambulatory basis. Mean follow-up was 7.6 months for all patients. In 27 patients, 52 translaminar screws were placed. There were no intraoperative complications. Postoperatively, we identified four screw malpositions using a new accuracy grading scale. One screw had to be revised because of violation of the spinal canal >4 mm. None of the patients had additional neurological deficits postoperatively, and all showed stable cervical conditions at follow-up. Two patients died due to causes not associated with the stabilization technique. The fusion rate for patients with C1/C2 fixation is 92.9%. Translaminar screws can be used at least as an additional technique for cases of upper cervical spine instability when pedicle screw placement is contraindicated or not possible. The current data suggest comparable biomechanical stability and fusion rates of translaminar screws to other well-known posterior fixation procedures. In addition, translaminar screw placement is technically less demanding and reduces the risk of vertebral artery injury.

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“…Approximately 12% of patients were considered at risk with unilateral anatomic variation, and another 6% were not suitable for screw fixation because of bilateral variation. In 2010, a three-dimensional CISS magnetic resonance imaging study 5 demonstrated that 40% of patients had significant anatomic variations on at least one side, prohibiting the insertion of transarticular screws. In another recent report, comprehensive computed tomography evaluation showed that the AA joint demonstrated larger variability in general, particularly in the sagittal plane.…”

Section: Anatomic Perspectivesmentioning

confidence: 99%

It Is Time to Abandon Atlanto-Axial Joint Injections: Do No Harm!

Datta

Manchikanti²

2011

Anesthesiology

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The idea of partial MAC values has become part of the clinical jargon, and it is-more or less-an accurate reflection of partial potency because the slopes of the relationships for sevoflurane and isoflurane are quite similar. Moreover, it is common practice for patients as well as animals to use MAC multiples to compare the effects of various inhalational anesthetics on a wide variety of physiologic endpoints-for example, brain acetylcholine level, 5 cerebral blood flow, 6 vasoconstriction, 7 cardiac function, 8 and hemodynamics. 9 In fact, many reviewers insist on the use of MAC multiples.As Dr. Cross suggests, in terms of equal points on two separate dose-response curves for our study, a more precise comparison would have been 1 MAC isoflurane versus 1 MAC sevoflurane. Unfortunately, neonatal mice do not tolerate prolonged exposure to isoflurane at 1 MAC without developing confounding physiologic derangements.10 Thus, we used a lower concentration, that, by design, is commonly used clinically. This clinical applicability was an essential goal of our study, to compare the neurotoxicity of two agents at concentrations used clinically. We certainly agree with Dr. Cross that a more thorough method of comparing anesthetic neurotoxic potency would involve constructing full doseresponse curves for apoptosis (or other endpoints) for each agent. Nevertheless, our results speak to common clinical practice as the immediate goal. We recognize that further work is necessary to establish the comparative mechanistic basis for these findings.

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Study of the Anatomical Variations of Vertebral Artery in C2 Vertebra With Magnetic Resonance Imaging and Its Application in the C1–C2 Transarticular Screw Fixation

Cited by 22 publications

References 21 publications

Análise tomográfica dos parâmetros anatômicos do áxis de crianças

Análise tomográfica dos parâmetros anatômicos do áxis de crianças

Translaminar screws of the axis—an alternative technique for rigid screw fixation in upper cervical spine instability

It Is Time to Abandon Atlanto-Axial Joint Injections: Do No Harm!

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