Morphometric Anatomy of the Posterior Aspect of the Atlas and the Vertebral Artery Groove in Relation to Lateral Mass Screw Placement

2021 ◽  
Author(s):  
Selda Aksoy ◽  
Bulent Yalcin
Keyword(s):  
Vertebral Artery ◽  
Screw Placement ◽  
Atlantoaxial Instability ◽  
Posterior Arch ◽  
Lateral Mass ◽  
Lateral Mass Screw ◽  
Entry Zone ◽  
Mean Width ◽  
The Mean ◽  
The Right

Abstract Background Atlantoaxial instability is an important disorder that causes serious symptoms such as difficulties in walking, limited neck mobility, sensory deficits, etc. Atlantal lateral mass screw fixation is a surgical technique that has gained important recognition and popularity. Because accurate drilling area for screw placement is of utmost importance for a successful surgery, we aimed to investigate morphometry of especially the posterior part of C1. Methods One hundred and fifty-eight human adult C1 dried vertebrae were obtained. Measurements were performed directly on dry atlas vertebrae, and all parameters were measured by using a digital caliper accurate to 0.01 mm for linear measurements. Results The mean distance between the tip of the posterior arch and the medial inner edge of the groove was found to be 10.59 ± 2.26 and 10.49 ± 2.20 mm on the right and left, respectively. The mean distance between the tip of the posterior arch and the anterolateral outer edge of the groove was 21.27 ± 2.28 mm (right: 20.96 ± 2.22 mm; left: 21.32 ± 2.27 mm). The mean height of the screw entry zone on the right and left sides, respectively, were 3.86 ± 0.81 and 3.84 ± 0.77 mm. The mean width of the screw entry zone on both sides was 13.15 ± 1.17 and 13.25 ± 1.3 mm. Conclusion Our result provided the literature with a detailed database for the morphometry of C1, especially in relation to the vertebral artery groove. We believe that the data in the present study can help surgeons to adopt a more accurate approach in terms of accurate lateral mass screw placement in atlantoaxial instability.

scholarly journals Posterior arch C-1 screw technique: a cadaveric comparison study

2017 ◽  
Vol 26 (6) ◽  
pp. 679-683 ◽  
Author(s):  
Marc Moisi ◽  
Christian Fisahn ◽  
Lara Tkachenko ◽  
Shiveindra Jeyamohan ◽  
Stephen Reintjes ◽  
...  
Keyword(s):  
Vertebral Artery ◽  
Nerve Root ◽  
Access Point ◽  
Screw Placement ◽  
Posterior Arch ◽  
Lateral Mass ◽  
Entry Site ◽  
Starting Point ◽  
The Right

OBJECTIVEPosterior atlantoaxial stabilization and fusion using C-1 lateral mass screw fixation has become commonly used in the treatment of instability and for reconstructive indications since its introduction by Goel and Laheri in 1994 and modification by Harms in 2001. Placement of such lateral mass screws can be challenging because of the proximity to the spinal cord, vertebral artery, an extensive venous plexus, and the C-2 nerve root, which overlies the designated starting point on the posterior center of the lateral mass. An alternative posterior access point starting on the posterior arch of C-1 could provide a C-2 nerve root–sparing starting point for screw placement, with the potential benefit of greater directional control and simpler trajectory. The authors present a cadaveric study comparing an alternative strategy (i.e., a C-1 screw with a posterior arch starting point) to the conventional strategy (i.e., using the lower lateral mass entry site), specifically assessing the safety of screw placement to preserve the C-2 nerve root.METHODSFive US-trained spine fellows instrumented 17 fresh human cadaveric heads using the Goel/Harms C-1 lateral mass (GHLM) technique on the left and the posterior arch lateral mass (PALM) technique on the right, under fluoroscopic guidance. After screw placement, a CT scan was obtained on each specimen to assess for radiographic screw placement accuracy. Four faculty spine surgeons, blinded to the surgeon who instrumented the cadaver, independently graded the quality of screw placement using a modified Upendra classification.RESULTSOf the 17 specimens, the C-2 nerve root was anatomically impinged in 13 (76.5%) of the specimens. The GHLM technique was graded Type 1 or 2, which is considered “acceptable,” in 12 specimens (70.6%), and graded Type 3 or 4 (“unacceptable”) in 5 specimens (29.4%). In contrast, the PALM technique had 17 (100%) of 17 graded Type 1 or 2 (p = 0.015). There were no vertebral artery injuries found in either technique. All screw violations occurred in the medial direction.CONCLUSIONSThe PALM technique showed statistically fewer medial penetrations than the GHLM technique in this study. The reason for this is not clear, but may stem from a more angulated ”up-and-in” screw direction necessary with a lower starting point.

Posterior C1 Stabilization Using Superior Lateral Mass as an Entry Point in a Case With Vertebral Artery Anomaly: Technical Case Report

2011 ◽  
Vol 68 (suppl_1) ◽  
pp. onsE246-onsE249 ◽  
Author(s):  
Jae Taek Hong ◽  
Woo Young Jang ◽  
Il Sup Kim ◽  
Seung Ho Yang ◽  
Jae Hoon Sung ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Vertebral Artery ◽  
Computed Tomography Angiography ◽  
Anatomical Variations ◽  
Entry Point ◽  
Screw Placement ◽  
Lateral Mass ◽  
Starting Point ◽  
Bursting Fracture ◽  
The Right

Abstract BACKGROUND AND IMPORTANCE: This is the first report of using the superior lateral mass as an alternative starting point for C1 posterior screw placement, demonstrating the importance of recognizing vertebral artery (VA) anomaly in deciding the surgical strategy for C1 screw placement. CLINICAL PRESENTATION: A 56-year-old man presented with severe neck pain after a fall. Imaging demonstrated an unstable bursting fracture at C4, C1-2 instability, and a subluxation at C2-3. Computed tomography angiography indicated that the persistent first intersegmental artery was located on the left side. The patient underwent anterior-posterior cervical fixation and fusion. Posterior C1 fixation was done with polyaxial screw rod construct using C1 superior lateral mass on the left side and C1 inferior lateral mass on the right side. The patient had no immediate postoperative deficits. At the 8-month follow-up examination, the patient was neurologically intact with a solid cervical fusion. CONCLUSION: The third segment of the VA is heterogeneous; therefore, preoperative radiologic studies should be performed to identify any anatomical variations. Using preoperative 3-dimensional computed tomography angiography, we can precisely identify an anomalous VA, thereby significantly reducing the risk of VA injury. To avoid significant morbidities associated with VA injury, a more optimal entry point for C1 fixation can be selected if a persistent first intersegmental artery or fenestrated VA is detected.

Rotational vertebral artery occlusion from occipital bone anomaly: a rare cause of embolic stroke

2002 ◽  
Vol 97 (6) ◽  
pp. 1456-1459 ◽  
Author(s):  
Teiji Tominaga ◽  
Toshiyuki Takahashi ◽  
Hiroaki Shimizu ◽  
Takashi Yoshimoto
Keyword(s):  
Vertebral Artery ◽  
Three Dimensional ◽  
Craniovertebral Junction ◽  
Artery Occlusion ◽  
Occipital Bone ◽  
Atlantoaxial Instability ◽  
Posterior Arch ◽  
Content Type ◽  
The Right ◽  
Fine Print

✓ Vertebral artery (VA) occlusion by rotation of the head is uncommon, but can result from mechanical compression of the artery, trauma, or atlantoaxial instability. Occipital bone anomalies rarely cause rotational VA occlusion, and patients with nontraumatic intermittent occlusion of the VA usually present with compromised vertebrobasilar flow. A 34-year-old man suffered three embolic strokes in the vertebrobasilar system within 2 months. Magnetic resonance imaging demonstrated multiple infarcts in the vertebrobasilar territory. Angiography performed immediately after the third attack displayed an embolus in the right posterior cerebral artery. Radiographic and three-dimensional computerized tomography bone images exhibited an anomalous osseous process of the occipital bone projecting to the posterior arch of the atlas. Dynamic angiography indicated complete occlusion of the left VA between the osseous process and the posterior arch while the patient's head was turned to the right. Surgical decompression of the VA resulted in complete resolution of rotational occlusion of the artery. An occipital bone anomaly can cause rotational VA occlusion at the craniovertebral junction in patients who present with repeated embolic strokes resulting from injury to the arterial wall.

scholarly journals An Anatomical Study of the Morphometric Differences between Complete Arcuate Foramina and Ipsilateral Foramina Transversaria in Human Atlas Vertebrae: Could these Be Responsible for Vaso-occlusive Symptoms?

2019 ◽  
Vol 08 (03) ◽  
pp. 106-111
Author(s):  
Monika Lalit ◽  
Anupama Mahajan ◽  
Sanjay Piplani ◽  
Jagdev S. Kullar
Keyword(s):  
Vertebral Artery ◽  
Anatomical Study ◽  
Cross Sectional Area ◽  
Posterior Arch ◽  
Sectional Area ◽  
Cross Sectional ◽  
Significant Difference ◽  
The Mean ◽  
The Difference ◽  
The Right

Abstract Background and Aims Arcuate foramina (AF), the atlas bridges formed by a delicate bony spicule over the posterior arch of atlas, have been implicated in the compression of the vertebral artery during extreme rotation of head and neck movements. Reduction in the size of arcuate foramina as compared with foramen transversarium (FT) is also an important cause for the compression of vertebral artery. Aim of the present study was to determine the morphometric differences between complete AF and ipsilateral foramina transversaria. Materials and Methods Eighty dry adult human atlas vertebrae were obtained in the Department of Anatomy, Government Medical College and Sri Guru Ram Das Institute of Medical Sciences and Research, Amritsar, Punjab, India. Measurements were taken of the maximum dimensions of AF and ipsilateral FT and cross-sectional area was also calculated. Results The following results were obtained.The AF were seen in total 11 (13.75%) vertebrae, 3 (3.75%) on the right side, 6 (7.5%) on left side, and 2 (2.5%) bilateral.• The mean ventrodorsal (AFL) and superoinferior (AFH) diameter of AF was 8.79 mm and 5.98 mm, and 8.11 mm and 5.54 mm on the right and left sides, respectively, and the difference was found to be highly significant.• The mean ventrodorsal (FTL) and mediolateral (FTW) diameter of the FT 8.19 mm and 6.56 mm, and 7.31 mm and 6.86 mm on the right and left sides, respectively, with significant difference on the right side.• The mean cross-sectional area of AF was 41.32 mm2 and 35.38 mm2, and FT was 42.53 mm2 and 39.71 mm2 on the right and left sides, respectively, and AF has smaller area than ipsilateral FT. Conclusions Knowledge about the dimensions and cross-sectional area of the AF and ipsilateral foramina transversaria of the atlas vertebra can improve the success rate of surgeries, thus preventing damage to the adjoining vital structures.

Computed tomography morphometric analysis for C-1 lateral mass screw placement in children

2009 ◽  
Vol 3 (1) ◽  
pp. 20-23 ◽  
Author(s):  
Roukoz B. Chamoun ◽  
William E. Whitehead ◽  
Daniel J. Curry ◽  
Thomas G. Luerssen ◽  
Andrew Jea
Keyword(s):  
Morphometric Analysis ◽  
Entry Point ◽  
Posterior Arch ◽  
Lateral Mass ◽  
Confined Space ◽  
Lateral Mass Screw ◽  
Screw Length ◽  
Entry Points ◽  
Left And Right ◽  
The Mean

Object The use of C-1 lateral mass screws provides an alternative to C1–2 transarticular screws in the pediatric population. However, the confined space of the local anatomy and unfamiliarity with the technique may make the placement of a C-1 lateral mass screw more challenging, especially in the juvenile or growing spine. Methods A CT morphometric analysis was performed in 76 pediatric atlases imaged at Texas Children's Hospital from October 1, 2007 until April 30, 2008. Critical measurements were determined for potential screw entry points, trajectories, and lengths, with the goal of replicating the operative technique described by Harms and Melcher for adult patients. Results The mean height and width for screw entry on the posterior surface of the lateral mass were 2.6 and 8.5 mm, respectively. The mean medially angled screw trajectory from an idealized entry point on the lateral mass was 16° (range 4 to 27°). The mean maximal screw depth from this same ideal entry point was 20.3 mm. The overhang of the posterior arch averaged 6.3 mm (range 2.1–12.4 mm). The measurement between the left- and right-side lateral masses was significantly different for the maximum medially angled screw trajectory (p = 0.003) and the maximum inferiorly directed angle (p = 0.045). Those measurements in children < 8 years of age were statistically significant for the entry point height (p = 0.038) and maximum laterally angled screw trajectory (p = 0.025) compared with older children. The differences between boys and girls were statistically significant for the minimum screw length (p = 0.04) and the anterior lateral mass height (p < 0.001). Conclusions A significant variation in the morphological features of C-1 exists, especially between the left and right sides and in younger children. The differences between boys and girls are clinically insignificant. The critical measurement of whether the C-1 lateral mass in a child could accommodate a 3.5-mm-diameter screw is the width of the lateral mass and its proximity to the vertebral artery. Only 1 of 152 lateral masses studied would not have been able to accommodate a lateral mass screw. This study reemphasizes the importance of a preoperative CT scan of the upper cervical spine to assure safe and effective placement of the instrumentation at this level.

Factors affecting lateral mass screw placement at C-7

2011 ◽  
Vol 14 (3) ◽  
pp. 405-411 ◽  
Author(s):  
Kalil G. Abdullah ◽  
Amy S. Nowacki ◽  
Michael P. Steinmetz ◽  
Jeffrey C. Wang ◽  
Thomas E. Mroz
Keyword(s):  
Sagittal Plane ◽  
Anatomical Variation ◽  
Axial Plane ◽  
Screw Placement ◽  
Lateral Mass ◽  
Lateral Mass Screw ◽  
Modified Technique ◽  
Modified Method ◽  
Starting Point ◽  
Lateral Mass Screws

Object The C-7 lateral mass has been considered difficult to fit with instrumentation because of its unique anatomy. Of the methods that exist for placing lateral mass screws, none particularly accommodates this anatomical variation. The authors have related 12 distinct morphological measures of the C-7 lateral mass to the ability to place a lateral mass screw using the Magerl, Roy-Camille, and a modified Roy-Camille method. Methods Using CT scans, the authors performed virtual screw placement of lateral mass screws at the C-7 level in 25 male and 25 female patients. Complications recorded included foraminal and articular process violations, inability to achieve bony purchase, and inability to place a screw longer than 6 mm. Violations were monitored in the coronal, axial, and sagittal planes. The Roy-Camille technique was applied starting directly in the middle of the lateral mass, as defined by Pait's quadrants, with an axial angle of 15° lateral and a sagittal angle of 90°. The Magerl technique was performed by starting in the inferior portion of the top right square of Pait's quadrants and angling 25° laterally in the axial plane with a 45° cephalad angle in the sagittal plane. In a modified method, the starting point is similar to the Magerl technique in the top right square of Pait's quadrant and then angling 15° laterally in the axial plane. In the sagittal plane, a 90° angle is taken perpendicular to the dorsal portion of the lateral mass, as in the traditional Roy-Camille technique. Results Of all the morphological methods analyzed, only a combined measure of intrusion of the T-1 facet and the overall length of the C-7 lateral mass was statistically associated with screw placement, and only in the Roy-Camille technique. Use of the Magerl technique allowed screw placement in 28 patients; use of the Roy-Camille technique allowed placement in 24 patients; and use of the modified technique allowed placement in 46 patients. No screw placement by any method was possible in 4 patients. Conclusions There is only one distinct anatomical ratio that was shown to affect lateral mass screw placement at C-7. This ratio incorporates the overall length of the lateral mass and the amount of space occupied by the T-1 facet at C-7. Based on this virtual study, a modified Roy-Camille technique that utilizes a higher starting point may decrease the complication rate at C-7 by avoiding placement of the lateral mass screw into the T1 facet.

scholarly journals Radiographic Measurement of Cochlear in Sudanese Population using High Resolution Computed Tomography (HRCT)

2021 ◽  
Vol 29 (2) ◽  
Author(s):  
Lubna Bushara ◽  
Mohamed Yousef ◽  
Ikhlas Abdelaziz ◽  
Mogahid Zidan ◽  
Dalia Bilal ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Hearing Loss ◽  
High Resolution ◽  
Temporal Bone ◽  
Healthy Subjects ◽  
Cochlear Nerve ◽  
High Resolution Computed Tomography ◽  
Mean Width ◽  
The Mean ◽  
The Right

This study aimed to determine the measurements of the cochlea among healthy subjects and hearing deafness subjects using a High Resolution Computed Tomography (HRCT). A total of 230 temporal bone HRCT cases were retrospectively investigated in the period spanning from 2011 to 2015. Three 64-slice units were used to examine patients with clinical complaints of hearing loss conditions at three Radiology departments in Khartoum, Sudan. For the control group (A) healthy subjects, the mean width of the right and left cochlear were 5.61±0.40 mm and 5.56±0.58 mm, the height were 3.56±0.36 mm and 3.54±0.36 mm, the basal turn width were 1.87±0.19 mm and 1.88 ±0.18 mm, the width of the cochlear nerve canal were 2.02±1.23 and 1.93±0.20, cochlear nerve density was 279.41±159.02 and 306.84±336.9 HU respectively. However, for the experimental group (B), the mean width of the right and left cochlear width were 5.38±0.46 mm and 5.34±0.30 mm, the height were 3.53±0.25 mm and 3.49±0.28mm, the basal turn width were 1.76±0.13 mm, and 1.79±0.13 mm, the width of the cochlear nerve canal were 1.75±0.18mm and 1.73±0.18mm, and cochlear nerve density were 232.84±316.82 and 196.58±230.05 HU, respectively. The study found there was a significant difference in cochlea’s measurement between the two groups with a p-value < 0.05. This study had established baseline measurements for the cochlear for the healthy Sudanese population. Furthermore, it found that HRCT of the temporal bone was the best for investigation of the cochlear and could provide a guide for the clinicians to manage congenital hearing loss.

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