Analysis of anatomical variations of bone and vascular structures around the posterior atlantal arch using three-dimensional computed tomography angiography

Hong, Jae Taek; Lee, Sang Won; Son, Byung Chul; Sung, Jae Hoon; Yang, Seung Ho; Kim, Il Sup; Park, Chun Kun

doi:10.3171/spi/2008/8/3/230

Cited by 156 publications

(108 citation statements)

References 20 publications

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“…10,13,15,17,20,23 On radiographic studies, the bridge was found in 11-15.6%. 4,11,20,24 The incidence of osseous bridges in our study was lower than those in past reports, and it is difficult to explain the cause of this wide disparity. This difference might result from the different modalities of investigation used, which have included cadaveric study, plain radiography study, and 3D CT study.…”

Section: Anatomical Variations and Anomaliescontrasting

confidence: 54%

“…The incidence of the osseous bridge may also vary among races across the world. 11,15 If the formation of the bridge relates to the aging process as osteophyte formation does, the incidence would vary depending on the patient population or the material used in each study. In the present investigation, when the extent of coverage was long enough to hide the VA or the VA itself was short, the VA showed little or no protrusion.…”

Section: Anatomical Variations and Anomaliesmentioning

confidence: 99%

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Posterolateral protrusion of the vertebral artery over the posterior arch of the atlas: quantitative anatomical study using three-dimensional computed tomography angiography

Yamaguchi¹,

Eguchi²,

Kiura³

et al. 2008

SPI

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Object The vertebral artery (VA) often takes a protrusive course posterolaterally over the posterior arch of the atlas. In this study, the authors attempted to quantify this posterolateral protrusion of the VA. Methods Three-dimensional CT angiography images obtained for various cranial or cervical diseases in 140 patients were reviewed and evaluated. Seven patients were excluded for various reasons. To quantify the protrusive course of the VA, the diameter of the VA and 4 parameters were measured in images of the C1–VA complex obtained in the remaining 133 patients. The authors also checked for anomalies and anatomical variations. Results When there was no dominant side, mean distances from the most protrusive part of the VA to the posterior arch of the atlas were 6.73 ± 2.35 mm (right) and 6.8 ± 2.15 mm (left). When the left side of the VA was dominant, the distance on the left side (8.46 ± 2.00 mm) was significantly larger than that of the right side (6.64 ± 2.0 mm). When compared by age group (≤ 30 years, 31–60 years, and ≥ 61 years), there were no significant differences in the extent of the protrusion. When there was no dominant side, the mean distances from the most protrusive part of the VA to the midline were 30.73 ± 2.51 mm (right side) and 30.79 ± 2.47 mm (left side). When the left side of the VA was dominant, the distance on the left side (32.68 ± 2.03 mm) was significantly larger than that on the right side (29.87 ± 2.53 mm). The distance from the midline to the intersection of the VA and inner cortex of the posterior arch of the atlas was ~ 12 mm, irrespective of the side of VA dominance. The distance from the midline to the intersection of the VA and outer cortex of the posterior arch was ~ 20 mm on both sides. Anatomical variations and anomalies were found as follows: bony bridge formation over the groove for the VA on the posterior arch of C-1 (9.3%), an extracranial origin of the posterior inferior cerebellar artery (8.2%), and a VA passing beneath the posterior arch of the atlas (1.8%). Conclusions There may be significant variation in the location and branches of the VA that may place the vessel at risk during surgical intervention. If concern is noted about the vulnerability of the VA or its branches during surgery, preoperative evaluation by CT angiography should be considered.

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Section: Anatomical Variations and Anomaliescontrasting

confidence: 54%

Section: Anatomical Variations and Anomaliesmentioning

confidence: 99%

Posterolateral protrusion of the vertebral artery over the posterior arch of the atlas: quantitative anatomical study using three-dimensional computed tomography angiography

Yamaguchi¹,

Eguchi²,

Kiura³

et al. 2008

SPI

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“…When making the decision as to which method is most appropriate, surgeons need to consider several individual patient factors, as follows. First, some types of vertebral artery anomalies such as a persistent first intersegmental artery and fenestrated vertebral artery may preclude the use of C1 lateral mass screws [27], which is usually used in conjunction with C2 pedicle screws. In Fig.…”

Section: Interpretation Of Study Resultsmentioning

confidence: 99%

Risk of vertebral artery injury: comparison between C1–C2 transarticular and C2 pedicle screws

et al. 2013

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BACKGROUND CONTEXT: To our knowledge, no large series comparing the risk of vertebral artery injury by C1-C2 transarticular screw versus C2 pedicle screw have been published. In addition, no comparative studies have been performed on those with a high-riding vertebral artery and/ or a narrow pedicle who are thought to be at higher risk than those with normal anatomy. PURPOSE: To compare the risk of vertebral artery injury by C1-C2 transarticular screw versus C2 pedicle screw in an overall patient population and subsets of patients with a high-riding vertebral artery and a narrow pedicle using computed tomography (CT) scan images and threedimensional (3D) screw trajectory software. STUDY DESIGN: Radiographic analysis using CT scans. PATIENT SAMPLE: Computed tomography scans of 269 consecutive patients, for a total of 538 potential screw insertion sites for each type of screw. OUTCOME MEASURES: Cortical perforation into the vertebral artery groove of C2 by a screw. METHODS:We simulated the placement of 4.0 mm transarticular and pedicle screws using 1-mm-sliced CT scans and 3D screw trajectory software. We then compared the frequency of C2 vertebral artery groove violation by the two different fixation methods. This was done in the overall patient population, in the subset of those with a high-riding vertebral artery (defined as an isthmus height #5 mm or internal height #2 mm on sagittal images) and with a narrow pedicle (defined as a pedicle width #4 mm on axial images). RESULTS: There were 78 high-riding vertebral arteries (14.5%) and 51 narrow pedicles (9.5%). Most (82%) of the narrow pedicles had a concurrent high-riding vertebral artery, whereas only 54% of the high-riding vertebral arteries had a concurrent narrow pedicle. Overall, 9.5% of transarticular and 8.0% of pedicle screws violated the C2 vertebral artery groove without a significant difference between the two types of screws (p5.17). Among those with a high-riding vertebral artery, vertebral artery groove violation was significantly lower (p5.02) with pedicle (49%) than with transarticular (63%) screws. Among those with a narrow pedicle, vertebral artery groove violation was high in both groups (71% with transarticular and 76% with pedicle screws) but without a significant difference between the two groups (p5.55). CONCLUSIONS: Overall, neither technique has more inherent anatomic risk of vertebral artery injury. However, in the presence of a high-riding vertebral artery, placement of a pedicle screw is significantly safer than the placement of a transarticular screw. Narrow pedicles, which might be anticipated to lead to higher risk for a pedicle screw than a transarticular screw, did not result in a significant difference because most patients (82%) with narrow pedicles had a concurrent highriding vertebral artery that also increased the risk with a transarticular screw. Except in case of a high-riding vertebral artery, our results suggest that the surgeon can opt for either technique and expect similar anatomic risks of vertebral artery i...

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“…9,10) The sagittal angle of the C0-C1 transarticular screw at the junctional entry point is significantly steeper than that at the caudal C1 arch point. Therefore, the caudal C1 arch point may be more convenient for screw insertion and screw head alignment with the other screws.…”

Section: Discussionmentioning

confidence: 99%

Biomechanical and Morphometric Evaluation of Occipital Condyle for Occipitocervical Segmental Fixation

Hong

Takigawa

Sugisaki

et al. 2011

Neurol. Med. Chir.(Tokyo)

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Two recent novel techniques of occipital fixation are the occipitoatlantal (C0-C1) transarticular screw technique and the direct occipital condyle screw technique. The present study evaluated and compared the biomechanical stability of the direct occipital condyle screw and C0-C1 transarticular screw with the established method for craniocervical spine fixation using the midline occipital keel screw and C1 lateral mass screw. Morphometric evaluation of the occipital condyle and the hypoglossal canal was performed to avoid hypoglossal nerve injury during the screw placement. Thirteen recently frozen cadaveric specimens were used. The occipital condyle anatomy and the hypoglossal canal dimension were measured using reconstructed computed tomography images. Insertion torque and pullout strength were evaluated to compare the midline occipital keel screw, C0-C1 transarticular screw, C1 lateral mass screw, and direct occipital condyle screw. The dimensions of the occipital condyle allow use of a 3.5 or 4.0-mm diameter screw. Mean pullout strength was 1619.6 N for the midline occipital keel screw, 870.7 N for the C0-C1 transarticular screw, 707.0 N for the C1 lateral mass screw, and 431.7 N for the direct occipital condyle screw. Mean insertion torque was 0.55 Nm for the midline occipital keel screw, 0.32 Nm for the C0-C1 transarticular screw, 0.14 Nm for the C1 lateral mass screw, and 0.11 Nm for the direct occipital condyle screw. The condylar anatomy allows direct insertion of the occipital condyle screw and C0-C1 transarticular screw. These techniques are suitable options for the treatment of craniovertebral junction instabilities in selected patients.

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Analysis of anatomical variations of bone and vascular structures around the posterior atlantal arch using three-dimensional computed tomography angiography

Cited by 156 publications

References 20 publications

Posterolateral protrusion of the vertebral artery over the posterior arch of the atlas: quantitative anatomical study using three-dimensional computed tomography angiography

Posterolateral protrusion of the vertebral artery over the posterior arch of the atlas: quantitative anatomical study using three-dimensional computed tomography angiography

Risk of vertebral artery injury: comparison between C1–C2 transarticular and C2 pedicle screws

Biomechanical and Morphometric Evaluation of Occipital Condyle for Occipitocervical Segmental Fixation

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