Bridging veins at the craniocervical junction: from anatomy to clinical significance in dural arteriovenous shunts.

PURPOSE: Bridging veins (BVs) serve as a route of pial venous reflux, and its anatomy is essential to understand the pathophysiology of dural arteriovenous shunts (dAVSs) around the craniocervical junction (CCJ) (from the jugular foramen level to the atlantal level). However, the anatomical variations of the BVs and their proximal connections remained poorly elucidated. This study aimed to radiologically investigate the anatomy of the bridging veins around CCJ and discuss the clinical significance of these BVs in the dAVS. METHODS: We investigated normal venous anatomy of the BVs from the jugular foramen level to the atlantal level using preoperative computed tomography digital subtraction venography in patients undergoing elective neurosurgery. BVs affected by the dAVSs in the same region were also evaluated. The three types of dAVS, craniocervical junction, anterior condylar, and proximal sigmoid sinus, were investigated. RESULTS: We identified six BV groups: superolateral, anterolateral, lateral, posterior, inferolateral, and inferoposterior. The superolateral and inferolateral groups, connected with the proximal sigmoid sinus and suboccipital cavernous sinus, respectively, were the largest groups. Each group has a specific downstream venous connection. The association with dVASs was observed only in the inferolateral group, which was typically the sole venous drainage in most dAVSs at the CCJ. CONCLUSION: We reported detailed anatomy of BVs from the jugular level to the atlantal level, which enhanced our understanding of the pathophysiology of dAVSs in the corresponding region.

Systematic review and meta-analysis of the prevalence of the retrotransverse foramen of the atlas.

The retrotransverse foramen (RTF) is a nonmetric variant of the atlas vertebra that can accommodate an anastomotic vertebral vein and occipital nerve. An understanding of this variation and its occurrence is crucial, as it could aid in explanation of the unidentified cause of the high prevalence of variability in this region. The aim of this meta-analysis was to obtain data on the prevalence of the RTF and its variations according to anatomy, sex, and ethnicity. A large-scale search was conducted through the major online databases to establish and determine the pool of studies reporting data relevant to the RTF. No date or language restrictions were applied. The data collection was categorized by prevalence, type (incomplete/complete), side, sex, ethnicity, laterality, and diameter. A total of 17 studies (n = 1979 subjects) were incorporated into our analysis. The overall pooled prevalence for a complete RTF was 11.4% and the overall pooled prevalence of an incomplete (partial) RTF was 9.6%. A complete RTF was most prevalent in Africa (Sub-Saharan population) (12.1%), followed by Europe (11.8%) and Asia (9.7%). As this variant occurs in a significant number of patients in all of the aforementioned populations, recognition, and awareness, especially with thorough investigation with computer tomography angiography (CTA) should be implemented, as it is the only possible way to visualize the possible contents of RTF.

Management of Unstable C1 Fractures Involving the Lateral Mass: Posterior C1-C2 Screw-Rod Fixation and Fusion.

BACKGROUND Although most unstable C1 fractures can be effectively treated either by conservative treatment with external immobilization or by surgical procedure of C1-ring osteosynthesis, those fractures involving the lateral mass are likely to lead to traumatic arthritis and persistent neck pain. Specific reports of treatment of unstable C1 fractures involving the lateral mass are still scarce. We therefore present this report to evaluate the effectiveness of posterior C1-C2 screw-rod fixation and fusion for unstable C1 fractures involving the lateral mass. MATERIAL AND METHODS From June 2009 to June 2016 in our hospital, 16 cases were diagnosed with C1 fractures involving the lateral mass and treated by posterior C1-C2 screw-rod fixation and fusion from June 2009 to June 2016. The patients' clinical data were retrospectively analyzed. Preoperative and postoperative images were taken to evaluate cervical sequence, location of screws, and bone fusion. Neurological status and neck pain levels were evaluated clinically on follow-up. RESULTS All patients underwent surgery successfully. The mean follow-up duration was 15.3±4.9 months (range 9-24 months). All patients obtained satisfying clinical outcomes with good neck pain alleviation, appropriate screw placement, and reliable bone fusion. None of the patients developed vascular or neurological complications during the operation or follow-up. CONCLUSIONS Posterior C1-C2 screw-rod fixation and fusion is an effective management for unstable C1 fractures involving the lateral mass. This operation can provide reliable stabilization and satisfactory bone fusion.

Posterior osteosynthesis with a new self-designed lateral mass screw-plate system for unstable atlas burst fractures.

BACKGROUND: In the treatment of unstable atlas fractures using the combined anterior-posterior approach or the posterior monoaxial screw-rod system, factors such as severe trauma or complex surgical procedures still need to be improved despite the favourable reduction effect. This research described and evaluated a new technique for the treatment of unstable atlas fracture using a self-designed lateral mass screw-plate system. METHODS: A total of 10 patients with unstable atlas fractures using this new screw-plate system from January 2019 to December 2021 were retrospectively reviewed. All patients underwent posterior open reduction and internal fixation (ORIF) with a self-designed screw-plate system. The medical records and radiographs before and after surgery were noted. Preoperative and postoperative CT scans were used to determine the type of fracture and evaluate the reduction of fracture. RESULTS: All 10 patients were successfully operated with this new system, with an average follow-up of 16.7 ± 9.6 months. A total of 10 plates were placed, and all 20 screws were inserted into the atlas lateral masses. The mean operating time was 108.7 ± 20.1 min and the average estimated blood loss was 98.0 ± 41.3 ml. The lateral mass displacement (LMD) averaged 7.1 ± 1.9 mm before surgery and almost achieved satisfactory reduction after surgery. All the fractures achieved bony healing without reduction loss or implant failure. No complications (vertebral artery injury, neurologic deficit, or wound infection) occurred in these 10 patients. At the final follow-up, the anterior atlantodens interval (AADI) was 2.3 ± 0.8 mm and the visual analog scale (VAS) was 0.6 ± 0.7 on average. All patients preserved almost full range of motion of the upper cervical spine and achieved a good clinical outcome at the last follow-up. CONCLUSIONS: Posterior osteosynthesis with this new screw-plate system can provide a new therapeutic strategy for unstable atlas fractures with simple and almost satisfactory reduction.

Posterior arch reconstruction in cervical surgery to restore the global biomechanics of the Atlas: a technical note.

The posterior arch of the atlas is usually not considered one of the main stabilizers of the cranio-cervical junction, allowing surgeons to its removal when needed with a relative certainty to preserve the stability of the atlo-axial segment. However, these considerations do not reflect the importance to examine the integrity of the posterior arch in the whole biomechanics of the atlas. Authors like Gebauer and Panjabi revealed, respectively in experimental and clinical conditions, how the atlas responds to an axial loading force, proving that the whole atlas is involved into horizontal conversion of axial forces and providing evidence supporting the preservation of the posterior arch. Other authors evaluated the risk for anterior arch fracture following C1 laminectomy. In this technical note three different techniques of posterior atlas arch reconstruction after surgical iatrogenic disruption are presented, considering both neoplastic and degenerative disease.

Paracondylar process combined with persistent first intersegmental vertebral artery: an anatomic case report and literature review.

The paracondylar process (PCP) and the persistent first intersegmental vertebral artery (PFIA) are both rare variations at the craniovertebral junction. We report the above two variations coexisting in one cadaveric head during the training of far lateral approach in our skull base lab. The specimen simultaneously had a left occipitalized atlas associated with a PFIA and a right PCP. The previous reports, the embryogenesis, and the clinical implications of the two variations were also reviewed. Preoperative recognition of the rare variations is essential to a safe far lateral approach.

Evaluation of Dimension and Bridging of Sella Turcica and Presence of Ponticulus Posticus in Individuals With and Without Cleft: A Comparative Study.

OBJECTIVE: Sella turcica abnormalities such as sella turcica bridging (STB) have been observed frequently among patients with craniofacial anomalies. Ponticulus posticus (PP) is an important structure and its presence causes complications during surgeries. Due to the importance of these structures, this study aimed to evaluate the prevalence of STB, PP, and dimensions of the sella turcica in individuals with and without cleft. DESIGN: A cross-sectional study. SETTING: Orthodontic and Radiology Departments in a public dental school, Tehran, Iran. PATIENTS: Eighty-three lateral cephalograms of individuals with cleft and ninety-two cephalograms of class I individuals without cleft. MAIN OUTCOME MEASURES: Length, depth, and maximum anterior-posterior diameter (APD) of sella turcica, presence of STB (classified as types 1, 2, and 3), and PP. RESULTS: In the group with cleft, 19.3% of individuals had type I, 65.1%, type II, and 15.7%, type III STB. In the group without cleft, 15.2% had type I, 73.9%, type II, and 10.9%, type III STB. In the group with cleft, 65.1% of individuals had no PP, 24.1%, incomplete, and 10.8%, complete PP while in the group without cleft, 56.5% had no PP, 29 31.5%, incomplete, and 12%, complete PP. CONCLUSION: The sella turcica dimensions, STB, and PP prevalence were not significantly different between individuals with and without cleft. The sella turcica length and prevalence of STB and PP were not affected by age, sex, and cleft type. However, the depth and the APD were affected by age.

Morphometric analysis of dry atlas vertebrae in a northeastern Thai population and possible correlation with sex.

PURPOSE: The uppermost segment of the cervical vertebra or atlas (C1) is a critically important anatomical structure, housing the medulla oblongata and containing the grooves for the C1 spinal nerve and the vertebral vessels. Variations of the C1 vertebra can affect upper spine stability, and morphometric parameters have been reported to differ by population. However, there are few data regarding these parameters in Thais. The use of this bone to predict sex and age has never been reported. METHODS: This study aimed to examine C1 morphometry and determine its ability to predict sex. Twelve diameter parameters were taken from the C1 vertebrae of identified skeletons (n = 104, males [n, 54], females [n, 50]). Correlation analysis was also performed for sex and age, which were predicted using machine learning algorithms. RESULTS: The results showed that 8 of the 12 measured parameters were significantly longer in the male atlas (p < 0.05), while the remaining 4 (distance between both medial-most edges of the transverse foramen, transverse dimension of the superior articular surface, frontal plane passing through the canal's midpoint, and anteroposterior dimension of the inferior articular surface) did not differ significantly by sex. There was no statistically significant difference in these parameters on the lateral side. The decision stump classifier was trained on C1 parameters, and the resulting model could predict sex with 82.6% accuracy (root mean square error = 0.38). CONCLUSION: Assertation of the morphometric parameters of the atlas is important for preoperative assessment, especially for the treatment of atlas dislocation. Our findings also highlighted the potential use of atlas measurements for sex prediction.

The Prevalence and Morphology-Wise Demographic Distribution of Ponticulus Posticus on CT Scans-A Retrospective Observational Study.

Background and Objectives: The ponticulus posticus (PP) is a bony bridge that emerges from the posterior aspect of the superior articular process, to connect the posterior arch of the atlas. It is often associated with neurological symptoms. The aim of this study was to obtain an insight into this malformation, and prevalence in the North East region of the Romanian population. Materials and methods: This anatomical variant was analyzed through an observational and retrospective study which was carried out in St. Spiridon Hospital Iasi. The duration of the study was 10 months and, a number of 487 patients who presented neurological symptoms without cranio-cerebral traumatisms were enrolled and a computed tomography (CT) scan was performed. We proposed a new classification of PP in five types. The prevalence of PP was calculated and Skewness test, ANOVA test with Bonferroni correction, and Student's t-test were used for statistical analysis. Results: Among the sample of 487 patients, PP was found in 170 cases (34.90%) in an age group of 8-90 years (mean age = 59.52 years, SD ± 19.94 years). Type I was found in 11.29%, followed by Type II-8.21%, Type III-5.13%, Type IV-5.54%, and Type V-4.72% (p = 0.347). It was 19.5%, mirroring the incomplete type, whereas the complete type was reported in 15.40% of cases (p = 0.347), the highest prevalence, namely 41.17% was found in the "41 to 60 years" age group, followed by 36.95% in the "21 to 40 years" group (p = 0.00148). The mean age was higher in patients with PP Type III (61.16 years, SD ± 19.98), while patients with PP Type V recorded the lowest mean age (56.48 years, SD ± 22.13). The differences between the comparative average ages on types were not statistically significant (p = 0.411). The gender and age were not good predictors of PP Type V (AUC < 0.600). Conclusion: according to our study, incomplete types of PP were found to be more prevalent as compared to complete types. No difference between males and females was detected. PP is more frequent in adults and young adults than in the elderly population. It is confirmed that gender and age were not good predictors of the bilateral complete type of PP.

Ponticulus Posticus: An Important Diagnostic Finding Often Missed in Lateral Cephalograms.

AIM: The purpose of the current study was to investigate the presence of the ponticulus posticus (PP) frequently encountered in lateral cephalograms. MATERIALS AND METHODS: About 500 patients of age 12-40 years were selected whose digital lateral cephalogram was recorded and traced to confirm the presence of the PP and categorize as: (A) Absent, as evidenced by lateral cephalograms. (B) Complete PP evidenced by the presence of circumferential bone bridge that connected the upper articular process to the atlas's posterior arch. (C) Partial PP: presented as a bone spike that protruded from the top articular process or the posterior arch of the atlas and extended above the vertebral artery sulcus. Symptoms of migraine, shoulder discomfort, orofacial pain, and headache were also evaluated on interaction with the patients. Using the Chi-square test, the relationship between the patient's gender and the presence of the PP was assessed. A p-value of 0.05 or less was regarded as statistically significant. RESULTS: About 10% of the patients reported with the presence of complete variant, 70% with partial variant and rest 20% of patients with neither a partial nor a complete form of PP. There was no statistically significant association between the PP and gender, as indicated by the Chi-square values (3.146; p = 0.526). CONCLUSION: On conclusion, according to the findings of the current study, patients with a complete form of PP experience more symptoms than those with a partial form of PP. In both groups, the PP frequency was higher in females. CLINICAL SIGNIFICANCE: In lateral cephalograms, the cervical spine region is typically ignored and given little weight. A common variation of atlas vertebrae is the PP, which is located in the posterior arch of the atlas. The PP exacerbates symptoms, such as migraine, tension headaches, shoulder pain, double vision, vertigo, stroke, and pain in the neck and orofacial region. Therefore, orthodontic specialists serve as initial diagnosticians and direct the patients to qualified physicians so that they can experience symptom relief.

Atlas and Talus.

This article explores the history of the terms atlas and talus and discusses the unexpected implications of their use in human anatomy. Renaissance anatomists decided to call the first cervical vertebra the atlas. But the name atlas was first used by the ancient Romans for the seventh cervical vertebra. The most common explanation why the first cervical vertebra is called atlas is that the vertebra holds up the globe of the cranium the way Atlas holds up the globe of the heavens. However, an important part of the myth of Atlas is that the Titan was being punished. The seventh cervical vertebra was so named due to its suitability for supporting burdens. (Pollux, 1900) Switching the designation atlas from the seventh to the first cervical vertebra in human anatomy implies that the point of man's burden has shifted from his shoulders to his head. What an anatomist is saying by making, or accepting, this change is that man's true burden is not a physical load, but rather, it is his mind. We explore the implications of this switch, and how it is represented in Renaissance anatomy diagrams. Long before the first cervical vertebra was called atlas it was known as the astragalus, the same term used for the talus, or ankle bone. We examine the many different terms that were used for the ankle bone during the Middle Ages and Renaissance, as well as the connection of the term talus with Greek mythology.

Atlas (C1) lateral mass screw placement using the intersection between lateral mass and inferomedial edge of the posterior arch: a cadaveric study.

PURPOSE: To compare the Atlas (C1) lateral mass screw placement between screw trajectories of 0° and 15° medial angulation while using the intersection between lateral mass and inferomedial edge of the posterior arch. METHODS: Forty-eight Atlas lateral masses were prepared and divided into 2 groups: Group 1; screws inserted at 3 mm lateral to the reference point with screw trajectory of 0° angulation(N = 24) and Group 2; those inserted with screw trajectory of 15° medial angulation(N = 24). We evaluated the atlas anatomy, screw purchase and the presence of any breaches using CT scan. RESULTS: The radiographic parameters for Groups 1 and 2 were found statistically different (p-value < 0.05): bilateral intraosseous screw lengths (17.92 ± 1.47 mm. vs. 20.71 ± 2.4 mm.), bilateral screw length (29.92 ± 1.72 mm. vs. 33.13 ± 1.78 mm.), left screw medial angulation (x°) (0.67° ± 0.78° vs.14.17° ± 3.51°), right screw medial angulation (y°) (0.83° ± 1.03° vs.14.25° ± 2.53°) and bilateral screw medial angulation (0.75° ± 0.9° vs. 14.21° ± 2.99°). Twenty-two screws (91.67%) using the 0° medial angulation and nineteen screws (79.17%) using the 15° medial angulation had no cortical violations (Grade 0). However, two screws (8.33%) with 0° medial angulation and five screws (20.83%) with 15° medial angulation had breach less than 2 mm (Grade 1). There were no screws with breach between 2 and 4 mm (Grade 2) or greater than 4 mm. (Grade 3). CONCLUSION: A starting point of 3-mm lateral to the intersection between lateral mass and inferomedial edge of the Atlas posterior arch can be safely and effectively used to insert C1 lateral mass using both 0° and 15° medial angulation.

Suitability of 3.5-mm screw for the atlas in children: a retrospective computed tomography analysis.

BACKGROUND: The growth and development of the atlas in children has not been studied to date using a large sample size. OBJECTIVE: To study whether a 3.5-mm screw is suitable for the atlas in children, to explore the anatomical size and development of the atlas in 0-14-year-old children, and to provide morphological basis for lateral mass screw internal fixation. METHODS: A Computed Tomography (CT) morphometric analysis was performed on 420 pediatric atlases. In the atlas, D1, D2, D3, D4, and α of the atlas lateral mass were measured. Statistical analysis was performed using one-way ANOVA and Students' t test. The least square method was used for the regression analysis of the change trend in anatomical structure. The curve with the greatest goodness of fit was used as the anatomic trend regression curve. RESULTS: D1, D2, D3, and D4 generally showed an increasing trend with age. The ranges of averages of D1, D2, D3, D4, and α in 0-14 year-old children were as follows: 4.576-9.202 mm, 9.560-25.100 mm, 3.414-10.554 mm, 11.150-27.895, and 12.41°-20.97°, respectively. The trends of the fitting curves of L1 and L3 were power functions, and those of L2 and L4 were logarithmic curves. CONCLUSIONS: CT examination could help in preoperative decision-making, and 3.5-mm screw was found to be suitable for lateral mass screw internal fixation in children aging 2 years and older. D1-D4 increased with age. This provided a certain reference to perform posterior atlantoaxial fusion in children and is of great significance to design posterior atlantoaxial screw in children.

The computed tomographic evaluation of bony bridge of C1 as bleeding risk factor at the screw placement.

PURPOSE: To investigate the prevalence and morphological characteristics of ponticulus posticus (PP) and ponticulus lateralis (PL) using computed tomography (CT) images on a large study sample of the Anatolian population. The presence of the PP and PL bridges can limit gap available for placement procedure through the bony elements of C1. Routine screw techniques are contraindicated because of high risk of fatal bleeding of vertebral artery (VA). METHODS: The CT images of 1000 subjects (500 males, 500 females) were examined for the morphological characteristics and presence of PP and PL. The anteroposterior diameter, superoposterior (transverse) diameter, surface area, and central thickness of the bony bridge of the PP, PL, and transverse foramina (TF). RESULTS: The prevalence of PP was 14.8%, and bilateral complete PP was the most common PP type at 6.8%. The prevalence of PL was 4.1% and left-side complete PL was the most common PL type at 1.2%. The prevalence of both PP and PL was more common in males and bilateral complete PP were more predominant in males (p = 0.004, p = 0.038, and p = 0.010, respectively). The surface area of PP and PL were determined to be smaller than the surface area of the ipsilateral TF (p < 0.001 and p = 0.042, respectively). CONCLUSION: PP is not an uncommon anatomic anomaly and PL is even less frequently encountered. The prevalence of PP and PL was more common in males and bilateral complete PP was more predominant in males. Detailed information about the prevalence and morphometry of the PP and PL obtained in the present study could guide the clinicians dealing with neurosurgery, physical medicine and rehabilitation, and radiology in their practice.

Isolated atlas-duplication as a manifestation of persistent proatlas: a case report.

PURPOSE: Atlas-duplication is an exceedingly rare dysplasia of the craniocervical junction. To the best of our knowledge, only two cases of atlas-duplication have been reported and these were associated with complete anterior rachischisis and os odontoideum. We aimed to report a case of isolated atlas-duplication of incidental finding and without attributable symptoms which makes it unique. METHODS: Following a normal coronarography for a suspected myocardial infarction, a 60-year-old-man with no significant medical history developed a transient ischemic attack that justified brain computed-tomography angiography. RESULTS: There was no evidence for cerebral ischemic lesion, intracranial occlusion or significant artery disease. Bone analysis revealed eight cervical vertebral segments with an additional vertebral level located between the occiput and the atlas. This vertebra presented all the morphological characteristics of an atlas vertebra except for hypoplasia of the left transverse process. An incomplete anterior rachischisis was associated, and there was no other abnormality of craniocervical junction. The clinical examination revealed no neck pain, no limitation of joint amplitude and no neurological deficit. Apart from preventive treatment of ischemic stroke, no orthopedic or surgical treatment was undertaken. After 1.5 years of radiological monitoring, the patient remains symptom-free. CONCLUSIONS: Atlas-duplication is an exceedingly rare dysplasia of the craniocervical junction that may be found isolated and incidentally. If this variation does not necessarily warrant specific treatment, brain CT angiography is recommended to detect anatomical variations of the vertebral arteries.

Osteoid Osteoma of the Atlas in a Boy: Clinical and Imaging Features-A Case Report and Review of the Literature.

Osteoid osteoma is a benign osteoblastic tumor, quite uncommon in the spine. We report a case of an osteoid osteoma involving the atlas in a 6-year-old boy, who presented with suboccipital pain and torticollis. Initial radiological findings were ambiguous as magnetic resonance imaging showed mainly edema of upper cervical soft tissues. The subsequent computed tomography depicted a lesion of left lamina of C1. As conservative treatment failed, the lesion was surgically resected and the patient became pain free. To our knowledge, this is the first case of osteoid osteoma involving the atlas associated with abnormal soft tissue reaction reported in literature.

Anterior reduction and C1-ring osteosynthesis with Jefferson-fracture reduction plate (JeRP) via transoral approach for unstable atlas fractures.

BACKGROUND: To introduce a novel transoral instrumentation in the treatment of unstable fractures of the atlas. METHODS: From January 2008 to May 2018, 22 patients with unstable C1 fractures who received Jefferson-fracture reduction plate (JeRP) via transoral approach were retrospectively analyzed. The case history and the radiographs before and after surgery were noted. The type of fracture, the reduction of the fracture, and position of the internal fixation were assessed through preoperative and postoperative CT scans. RESULTS: All 22 patients successfully underwent anterior C1-ring osteosynthesis using the JeRP system, with a follow-up of 26.84 ± 9.23 months. Among them, 9 patients had transverse atlantal ligament (TAL) injury, including 3 in Dickman type I and 6 in type II. The preoperative lateral mass displacement (LMD) decreased from 7.13 ± 1.46 mm to 1.02 ± 0.65 mm after the operation. Bone union was achieved in all patients without implant failure or loss of reduction. There were no surgery-related complications, such as wound infection, neurological deficit, or vertebral artery injury. However, atlantoaxial dislocation occurred in 3 patients with Dickman type I TAL injury 3 months postoperatively without any neurological symptoms or neck pain. CONCLUSIONS: Transoral C1-ring osteosynthesis with JeRP is an effective surgical strategy to treat unstable atlas fractures with a safe, direct, and satisfactory reduction. The primary indication for the JeRP system is an unstable fracture (Gehweiler type I/III) or/ and TAL injury (Dickman type II).

Traumatic injury to the unfused anterior arch of C1 in the setting of bipartite atlas.

We present a case of a pediatric patient with congenital unfused anterior and posterior arches of the atlas (C1), also known as bipartite atlas, who sustained a traumatic injury during gymnastics. A computed tomography (CT) scan of the cervical spine raised concern for abnormal separation of the midline cleft of the anterior arch of C1. Subsequent magnetic resonance imaging (MRI) showed focal, edema-like signal in the midline cleft of C1. She was advised by neurosurgery to remain in a hard cervical collar for 6 weeks. She recovered after conservative treatment and returned to gymnastics. This case shows that a congenital unfused anterior arch of the atlas identified on CT after cervical trauma should not always be interpreted as an incidental finding. If a superimposed injury is suspected, MRI helps evaluate for traumatic injury, particularly if it is associated with upper cervical pain and tenderness or pain with neck movements. An additional case reiterates our findings.

Sella turcica bridging and ponticulus posticus calcification in subjects with different dental anomalies.

INTRODUCTION: This study aimed to evaluate and compare the bridging and dimensions of the sella turcica and calcification of the ponticulus posticus in subjects with different dental anomalies. METHODS: Pretreatment records of orthodontic patients with palatally impacted canines (n = 95), mandibular second premolar agenesis (n = 45), maxillary lateral incisor agenesis (n = 75), tooth transpositions (TT, n = 25), peg-shaped maxillary lateral incisors (n = 30), and third molar agenesis (TMA, n = 145) were analyzed and compared with the control group (CG) consisting of 145 subjects with skeletal Class I malocclusion and no dental anomalies. The length, diameter, and depth of the sella turcica were calculated for each patient. The degree of sella turcica bridging was scored as type I, II, and III, whereas the extent of ponticulus posticus was classified as Class I, II, and III. RESULTS: Only decreases in the length and diameter of the sella turcica in subjects with TT were found to be statistically significant. Although type II bridging frequency was found to be significantly lower in subjects with mandibular second premolar agenesis, maxillary lateral incisor agenesis, TT, and TMA, type III bridging frequency was found to be significantly higher only in subjects with TMA. The decrease in Class I calcification frequencies and the increase in Class II calcification frequencies were found to be significant in subjects with palatally impacted canines, TT, and TMA compared with the CG. In addition, the presence of Class III calcification was found to be significantly more frequent in subjects with TMA than in the CG. CONCLUSIONS: Although type II and type III bridging frequencies were found to be higher than in previous studies because of the higher type II bridging frequency in the CG, type II bridging frequency was found to be insignificant. Furthermore, an increased frequency of ponticulus posticus calcification was observed in subjects with palatally impacted canines, TT, and TMA.

Associations among palatal impaction of canine, sella turcica bridging, and ponticulus posticus (atlas arcuate foramen).

INTRODUCTION: The palatal impaction of canine (PIC) can be predicted by some head and neck skeletal anomalies or variants. Since studies on this regard (especially vertebral anomalies) are scarce, this study was conducted. METHODS: This case-control study was done on 46 PIC orthodontic patients (34 females, 12 males) and 46 control orthodontic patients (36 females, 10 males). The diagnosis of PIC was done on lateral cephalographs and panoramic radiographs. On cephalographs, sella turcica bridging (occurrence and severity) and ponticulus posticus (occurrence and severity) were assessed. Associations between PIC, sella bridging, and ponticulus posticus were examined statistically (α = 0.05, ß ≤ 0.2). RESULTS: Cases' and controls' mean ages were 17.7 ± 4.0 and 17.4 ± 3.5, respectively. Of the case subjects, 22, 22, and 2 had respectively types I (normal), II, and III of sella bridging, while these numbers were 34, 12, and 0 in controls (chi-square P = 0.023 for severity, 0.010 for occurrence). Ponticulus posticus was observed in 28 cases (7 completed) and 17 controls (6 completed, P = 0.022 for occurrence, 0.056 for severity). Sella bridging was not associated with ponticulus posticus (Spearman P = 0.150). According to binary logistic regression, sella bridging can increase the odds of palatal canine impaction for OR = 2.8 times, while ponticulus posticus for OR = 2.6. Age and sex did not affect sella bridging or ponticulus posticus. CONCLUSIONS: Both sella bridging and ponticulus posticus can predict an increased rate of PIC for more than 2.5 times.