The retro-articular vertebral artery ring of the atlas and its significance

Does ponticulus posticus affect vertebral artery diameter

PURPOSE

Ponticulus Posticus, atlantooccipital ligament ossification-induced anomaly, surrounds the vertebral artery and the first cervical nerve root. It is believed to wrap around the first cervical nerve root and the vertebral artery, causing compression. We hypothesized that it would also reduce the diameter of the vertebral artery.

METHODS

Between January 1, 2022, and December 31, 2022, cervical spine CT scans taken for any reason were retrospectively reviewed. The images of 1365 patients suitable for evaluation were evaluated by two expert radiologists in 3 dimensions. Among patients with PP, those who underwent cervical angiography were identified for vertebral artery diameter measurement.

RESULTS

The average age of the 1365 individuals included in the study (732 males, 633 females) was 55.78 (± 18.85) with an age range of 1-96. Among this group, PP was detected in 288 individuals, resulting in a total prevalence of 21.1%. Right and left vertebral artery diameters were significantly lower in patients with complete PP compared to the absent group (p < 0,001, p < 0,001, respectively). Additionally, it was observed that width and height diameters and artery diameters were positively correlated in patients with Complete PP.

CONCLUSIONS

Ponticulus posticus can cause vertebrobasilar insufficiency by reducing the diameter of the vertebral artery. Therefore, imaging and detailed evaluation of this region are important in symptomatic patients.

Ponticulus posticus and skeletal malocclusion: A pilot study in a Southern Italian pre-orthodontic court

Purpose

Ponticulus posticus (PP) is a bony protrusion located between the posterior portion of the superior articular process and the posterolateral portion of a posterior arch of the atlas vertebrae in the cervical spine. The aim of this study is to verify the presence of different types of PP in a Southern Italian pre-orthodontic cohort to understand its correlation with skeletal class and maturity.

Methods

A case-control retrospective study was conducted, utilizing 212 latero-lateral telecranium radiographs to analyze skeletal maturity according to the cervical vertebral maturation method, the Angle's classification of malocclusion (I, II, or III), and the presence or absence of the PP, whether complete (c-PP) or partial (p-PP). A total of 212 lateral cephalograms were analyzed.

Results

Of the 72 male patients, 67 (93%) exhibited PP, and 116 (88%) were PP. The chi-square value was 0.001, while Cramer's V was 0.270, indicating a significant correlation between age groups and PP presence, and a very strong association overall. Out of the 41 complete PP cases, class I was notably more prevalent than classes II and III.

Conclusion

Orthodontists should carefully consider PP when assessing and treating individuals with or without skeletal discrepancies and dental anomalies.

A comprehensive review of the vertebral artery anatomy

BACKGROUND

The vertebral arteries (VA) play a critical role by supplying nearly one-third of the brain's blood flow, predominantly contributing to the posterior circulation. These arteries may need to be exposed in a various cranial and cervical procedures and offers access to investigate or treat vascular lesions by endovascular means related to the posterior circulation. Given its complex anatomy, which is subject to numerous variations, and its role in supplying vital brain regions, a thorough understanding of the VA's anatomy is paramount for any related procedure.

OBJECTIVE

To provide a comprehensive overview of vertebral artery anatomy and its relevance in contemporary clinical practice.

METHODS

Dissection of the entire vertebral artery length using cadaveric specimen, combined with a comprehensive literature review.

RESULTS

The vertebral artery can be subdivided into four segments. Each of these segments has its own unique topographic anatomy with its variations, anastomoses, and significance in surgery.

CONCLUSION

As surgical and endovascular techniques continue to evolve with technological improvements, we are now more equipped than ever to manage complex lesions involving the VA. However, with its increasingly complexity comes the necessity for a deeper and more comprehensive understanding of the VA. Possessing the detailed knowledge of the VA is vital for the successful execution of any procedure involving it.

[Frequency of Ponticulus posticus and Ponticulus lateralis in patients admitted to hospital with traumatic brain injur]

OBJECTIVE

To determine the frequency of Ponticulus posticus and Ponticulus lateralis among patients admitted to a24-hour emergency hospital.

MATERIAL AND METHODS

The study included 2887 patients with a traumatic history who were admitted to the hospital for emergency reasons. This principle of sampling allowed us to exclude a high concentration of studies of patients with chronic neurological diseases, the cause of which could be symptomatic Kimmerle's anomaly (KA). During the period 01.01.20 to 31.12.20, primary CT was performed on an emergency basis in 7348 patients. Of these, CT scans of the brain and cervical spine were performed in 2965 patients. Some patients (78 people) were excluded from the study due to the presence of cervical vertebral fractures and metal artifacts in the craniovertebral region.

RESULTS

The Ponticulus posticus was detected in 1162 (40.2%) patients, among them class 3 and 4 was detected in 27.7%, and class 2 ossification in 12.5%. This Ponticulus posticus was significantly more common (χ2 test, p=0.0005) in men. The Ponticulus lateralis was identified in 231 patients (8%), among them 94 patients (3.3%) had complete ponticulus on both sides, 29 patients (1%) - on one side, and 108 patients (3.7%) - two-sided incomplete ponticulus. In patients with class 2-3-4, Ponticulus lateralis were detected significantly more often (χ2 test, p<0.0001).

CONCLUSION

The cumulative incidence of KA was 42%, 17% of patients are carriers of a complete KA bridge, which is significantly higher than in the European or Asian regions. The data suggest that KA is not the result of ossification of the posterior atlanto-occipital membrane, since different classes of KA occur equally often at different ages. Further studies of KA are needed, including its occurrence in patients of the neurological department and its correlation with individual neurological syndromes to determine the need for surgical treatment in the population.

Prevalence of Ponticulus Posticus and Migraine in 220 Orthodontic Patients: A Cross-Sectional Study

BACKGROUND

Ponticulus posticus (PP) is a medical term that describes an anomaly of the atlas (C1), which has a complete or partial bone bridge over the vertebral artery (VA) groove. The purpose of the study is to estimate the prevalence of PP in patients with a diagnosis of migraine.

METHODS

Cone beam CT (CBCT) scans (n = 220) were reviewed for the detection of PP in the University "G. D'Annunzio" of Chieti in the Department of Medical, Oral and Biotechnological Sciences. The sample included 220 Italian patients between 18 and 87 years. Pearson chi-square analysis (p < 0.05 and 95% CI) was used to establish an association between migraine and PP.

RESULTS

The present study found a prevalence of PP of 20.9% and a prevalence of migraine of 12.272%. The association between migraine and PP was confirmed by the chi-square statistic, since the p-value was 0.008065 (significant at p < 0.05). PP was more frequent in the migraine without aura group, without a statistical difference relative to the migraine with aura group.

CONCLUSIONS

The study concluded that PP is positively associated with migraine.

Prevalence of ponticulus posticus on the posterior arch of the atlas in symptomatic and asymptomatic patients

OBJECTIVE

To calculate the prevalence of ponticulus posticus and its association with headache.

METHODS

The presence and types of ponticulus posticus were investigated on 640 digital lateral cephalograms. Patients with complete or partial ponticulus posticus were further evaluated and questioned for a history of cervicogenic headache. Dissemination of attain values was analyzed using a Chi-Square test, and p values < 0.05 were considered statistically significant.

RESULTS

The prevalence of ponticulus posticus in our study was 9.8%, with complete form in 45 (7%) patients of which 29 (64.5%) were male and 16 (35.5%) were female. Partial ponticulus posticus was found in 18 (2.8%) of patients, of which 12 (66.6%) patients were male and six (33.33%) were female. In patients with the complete form of ponticulus posticus, 37 (82.22%) were symptomatic. Among these 37 patients, 22 (59.45%) were male and 15 (40.54%) were female. In complete ponticulus posticus patients, symptoms were slightly worse in males than females. Whereas in partial ponticulus posticus, 13 (72.22%) patients were found to be symptomatic. Of these 13 patients, seven (53.84%) were male and six (46.15%) were female. Of the 72 patients with a history of cervical pain, 50 (69.44%) showed ponticulus posticus on a lateral cephalogram. Of the 568 patients with no history of cervical pain, only 13 (2.2%) showed ponticulus posticus on the lateral cephalogram.

CONCLUSION

This study examination showed that ponticulus posticus is a common anatomic variation often associated with tension-type headaches.

Assessments of Prevalence of Ponticulus Posticus, Atlas Posterior Arch Deficiency, Sella Turcica Bridging, Maxillary Canine Impaction, and Associations Among Them in 500 CBCTs of Italian Orthodontic Patients

Background: The ponticulus posticus (PP) is an important anomaly of the atlas (C1 vertebra) with a complete or partial bone bridge that transforms the groove of the vertebral artery (VA) into a canal (arcuate foramen). The aim was to retrospectively determine prevalence of PP evaluating morphological features and the possible association with other dentoskeletal anomalies in the midface and neck area such as maxillary canine impaction (MCI), atlas posterior arch deficiency (APAD), and sella turcica bridging (SB).

Methods: This study was conducted in the Department of Medical, Oral and Biotechnological Sciences of the University “G. D'Annunzio” in Chieti. The detection of PP was performed on 500 patients with cone beam CT (CBCT) images (6 to 87 years).

Results: Analysis revealed the presence of uni- and bi-lateral PP in 110 patients (22%): 24 (4.8%) patients with bilateral complete PP, 12 (2.4%) patients with complete PP on the left, 6 (1.2%) patients with complete PP on the right, 8 (1.6%) patients with complete PP on the right and partial PP on the left, 6 (1.2%) patients with complete PP on the left and partial PP on the right, 26 (5.2%) patients with partial bilateral PP, 18 (3.6%) patients with partial left PP, and 10 (2%) patients with partial PP on the right. The Chi-squared statistic confirmed that there are significant associations between MCI and PP (p = 0.020) and between SB and MCI (p &lt;0.00001). No correlation between chronological age and presence of the PP (p = 0.982), between chronological age and morphotypes of the PP (p = 0.779), between APAD and the PP (p = 0.0757), between SB and the PP (p = 0.111), and between APAD and MCI (p = 0.222) were found.

Conclusion: This observational study showed how bilateral partial variant and bilateral complete variant are the most represented morphotypes in all the age groups. The prevalence of MCI is positively associated with PP and with SB.

Anatomical Variation and Morphometric Study on Foramen Transversarium of the Upper Cervical Vertebrae in the Thai Population

Study Design

Foramen transversarium (FT) and foramen arcuale (FA) of upper cervical vertebrae (C1 and C2) in the Thai population were investigated for variation and morphometry.

Purpose

This study aimed to reveal the morphometry of FT and FA in the Thai population.

Overview of Literature

The FT and FA are structures found in the upper spine that support the vertebral neurovascular system. Clinically, the surgical approaches to achieve upper cervical stability can be affected by spine variations. FT and FA morphometries have been documented to vary by nationality. However, such reports have been limited in the Thai population.

Methods

The FT and FA of dried C1 and C2 vertebrae (identified bones; n=107, males=53 and females=54) were observed and measured using a Digital Vernier Caliper (Mitutoyo, Kawasaki, Japan). Anteroposterior (AP) and transverse diameters of the left and right FTs (n=214) were measured and compared between sexes. Variations and types of FT and FA found on the upper vertebrae were recorded and classified.

Results

The FT shape of the Thai C1 was AP elliptical, while of that of C2 was transverse elliptical. Compared to females, both diameters of the upper spine were significantly greater in males except for the AP diameter of C2 on the right side. All diameters were significantly different in both sexes and sides except for the AP diameter of C1 and C2. A common type of FT classified in C1 was type 2 (male [69.81%], female [79.63%]) whereas for C2 it was type 1 (male [63.21%], female [59.26%]). Moreover, an incomplete osseous bridge was a major FA subtype observed in the Thai spine.

Conclusions

FT morphometry has an elliptical shape and diameters are greater in males. The FT and FA variations identified in this study will be useful for surgeons treating vertebral neurovascular injuries of the posterior upper cervical spine in the Thai population.

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, β ≤ 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.

Earliest axial fossils from the genus Australopithecus

Australopitheus anamensis fossils demonstrate that craniodentally and postcranially the taxon was more primitive than its evolutionary successor Australopithecus afarensis. Postcranial evidence suggests habitual bipedality combined with primitive upper limbs and an inferred significant arboreal adaptation. Here we report on A. anamensis fossils from the Assa Issie locality in Ethiopia's Middle Awash area dated to ∼4.2 Ma, constituting the oldest known Australopithecus axial remains. Because the spine is the interface between major body segments, these fossils can be informative on the adaptation, behavior and our evolutionary understanding of A. anamensis. The atlas, or first cervical vertebra (C1), is similar in size to Homo sapiens, with synapomorphies in the articular facets and transverse processes. Absence of a retroglenoid tubercle suggests that, like humans, A. anamensis lacked the atlantoclavicularis muscle, resulting in reduced capacity for climbing relative to the great apes. The retroflexed C2 odontoid process and long C6 spinous process are reciprocates of facial prognathism, a long clivus and retroflexed foramen magnum, rather than indications of locomotor or postural behaviors. The T1 is derived in shape and size as in Homo with an enlarged vertebral body epiphyseal surfaces for mitigating the high-magnitude compressive loads of full-time bipedality. The full costal facet is unlike the extant great ape demifacet pattern and represents the oldest evidence for the derived univertebral pattern in hominins. These fossils augment other lines of evidence in A. anamensis indicating habitual bipedality despite some plesiomorphic vertebral traits related to craniofacial morphology independent of locomotor or postural behaviors (i.e., a long clivus and a retroflexed foramen magnum). Yet in contrast to craniodental lines of evidence, some aspects of vertebral morphology in A. anamensis appear more derived than its descendant A. afarensis.

Frequency and type of ponticulus posticus in a longitudinal sample of nonorthodontically treated patients: relationship with gender, age, skeletal maturity, and skeletal malocclusion

OBJECTIVES

The aim of this study was to assess the frequency and type of ponticulus posticus and to evaluate its relationship to gender, chronologic age, skeletal maturity, and skeletal malocclusion.

STUDY DESIGN

The sample included the longitudinal lateral cephalograms of 734 patients (378 males and 356 females) retrieved from the American Association of Orthodontists Craniofacial Growth Legacy Collection. The presence of ponticulus posticus (complete and partial forms) was assessed by visual inspection, and the cervical vertebral maturation method was used to determine the skeletal maturation stage. The presence and type (complete or partial) of ponticulus posticus were assessed by gender, age at first appearance of ponticulus posticus, skeletal maturation stage as determined by the cervical vertebral maturation method, and skeletal malocclusion.

RESULTS

The overall prevalence of ponticulus posticus was 12.6% (93 of 734) with complete and partial forms observed respectively in 8.7% (64 of 734) and 3.9% (29 of 734) of the sample. Both forms of ponticulus posticus occurred mainly in the age range of 7 to 13 years (P = .04). No differences were found in groups based on gender, skeletal maturity stages, or skeletal malocclusion (P > .05). However, approximately 90% of ponticulus posticus occurred before and after the circumpubertal stage.

CONCLUSIONS

Ponticulus posticus should be expected mainly during childhood and the pubertal age. This may support the theory of a genetic cause of this vertebral anomaly.

Prevalence of foramen arcuale and its clinical significance: a meta-analysis of 55,985 subjects

OBJECTIVE

The foramen arcuale (FA) is a bony bridge located over the vertebral artery on the posterior arch of the atlas. The presence of an FA can pose a risk during neurosurgery by providing a false impression of a broader posterior arch. The aim of this study was to provide the most comprehensive investigation on the prevalence of the FA and its clinically important anatomical features.

METHODS

Major electronic databases were searched to identify all studies that reported relevant data on the FA and the data were pooled into a meta-analysis.

RESULTS

A total of 127 studies (involving 55,985 subjects) were included. The overall pooled prevalence of a complete FA was 9.1% (95% CI 8.2%–10.1%) versus an incomplete FA, which was 13.6% (95% CI 11.2%–16.2%). The complete FA was found to be most prevalent in North Americans (11.3%) and Europeans (11.2%), and least prevalent among Asians (7.5%). In males (10.4%) the complete FA was more common than in females (7.3%) but an incomplete FA was more commonly seen in females (18.5%) than in males (16.7%). In the presence of a complete FA, a contralateral FA (complete or incomplete) was found in 53.1% of cases.

CONCLUSIONS

Surgeons should consider the risk for the presence of an FA prior to procedures on the atlas in each patient according to sex and ethnic group. We suggest preoperative screening with computerized tomography as the gold standard for detecting the presence of an FA.

How common is ponticulus posticus on lateral cephalograms?

Background

Ponticulus posticus is an anomaly of first cervical vertebra visible on lateral cephalogram and has some serious medical and surgical implications. Unfortunately, it is often overlooked or undetected by orthodontists. The general objective of this study is to sensitize orthodontists about this anomaly by depicting its prevalence among a group of Nepalese orthodontic patients.

Methods

Four hundred and fourteen digital lateral cephalograms of orthodontic patients were retrieved from the archives of the department. The lateral cephalograms were carefully assessed for the presence of ponticulus posticus in the posterior spine of atlas vertebra by two investigators independently and the findings were recorded.

Results

Ponticulus posticus was observed in 35.7% of the cases, of which 30.9% had partial ponticulus posticus and 4.8% had complete ponticulus posticus. Even though there was some female predilection, no statistically significant association was found between gender of the patient and presence of ponticulus posticus.

Conclusion

Ponticulus posticus is a fairly common anomaly with more than one-third (35.7%) of a group of Nepalese orthodontic patients affected and is independent of gender. Since, this anomaly is associated with numerous medical conditions and has surgical implications, orthodontists should use lateral cephalogram as screening radiograph for this anomaly.

Electronic supplementary material

The online version of this article (doi:10.1186/s13104-017-2494-z) contains supplementary material, which is available to authorized users.

Ponticulus posticus: Morphometric analysis and Its anatomical Implications for occipito-cervical fusion

OBJECTIVE

The purpose of this study was to evaluate the morphometric characteristics of ponticulus posticus (PP) and determine the impact of two promising high cervical operations (posterior arch to lateral mass screw fixation (PALMSF) and occipital condyle fixation (OCF)).

PATIENTS AND METHODS

We evaluated retrospective data from a total of 2628 head and neck 3-dimensional CT-angiographies (3D-CTA) that did not have bony or vascular abnormalities. The PP anomaly cases were confirmed, then we measured vertebral artery groove height (VAGH), arch to vertebral artery distance (AVD) and posterior arch height (PAH) for PALMSF. We also measured the vertebral artery to occipital bone distance (VOD) for OCF.

RESULTS

In 186 patients (7.1%), 227 PP (complete or near complete) were identified and this anomaly was more common in males and on the left side. The mean VAGH and PAH values ranged from 5.0 to 6.0mm and from 7.0 to 8.8mm, respectively. The VAGH value was not statistically different, regardless of the presence of PP, and the feasibility (>4mm) of a safe PALMSF (range, 87.7-100%) was not influenced by PP anomalies. The mean value of VOD in the anomaly side (range, 6.0-8.0mm) was much higher than for normal side (range, 4.2-5.7mm) and the proportion of patients that had a safe OCF (>3.5mm) was also much higher (range, 90.8-96.9%) than for the normal side.

CONCLUSIONS

A PP anomaly might have some anatomical feasibility and advantage during PALMSF and OCF, due to the relatively sufficient bony (VAGH) and spatial regions (VOD). However, there are gender differences in anatomical dimensions (VAGH, VOD and AVD); therefore, surgery in female patients should be approached more cautiously in the future.

Anatomical Variant of Atlas : Arcuate Foramen, Occpitalization of Atlas, and Defect of Posterior Arch of Atlas

Objective

We sought to examine anatomic variations of the atlas and the clinical significance of these variations.

Methods

We retrospectively reviewed 1029 cervical 3-dimensional (3D) CT images. Cervical 3D CT was performed between November 2011 and August 2014. Arcuate foramina were classified as partial or complete and left and/or right. Occipitalization of the atlas was classified in accordance with criteria specified by Mudaliar et al. Posterior arch defects of the atlas were classified in accordance with criteria specified by Currarino et al.

Results

One hundred and eight vertebrae (108/1029, 10.5%) showed an arcuate foramen. Bilateral arcuate foramina were present in 41 of these vertebrae and the remaining 67 arcuate foramina were unilateral (right 31, left 36). Right-side arcuate foramina were partial on 18 sides and complete on 54 sides. Left-side arcuate foramina were partial on 24 sides and complete on 53 sides. One case of atlas assimilation was found. Twelve patients (12/1029, 1.17%) had a defect of the atlantal posterior arch. Nine of these patients (9/1029, 0.87%) had a type A posterior arch defect. We also identified one type B, one type D, and one type E defect.

Conclusion

Preoperative diagnosis of occipitalization of the atlas and arcuate foramina using 3D CT is of paramount importance in avoiding neurovascular injury during surgery. It is important to be aware of posterior arch defects of the atlas because they may be misdiagnosed as a fracture.

Prevalence and Morphologic Characteristics of Ponticulus Posticus: Analysis Using Cone-Beam Computed Tomography

OBJECTIVE

This study evaluated the prevalence and morphologic characteristics of ponticulus posticus (PP) by using cervical 3-dimensional (3-D) cone-beam computed tomography (CBCT) scan images.

METHODS

This was a retrospective study conducted by selecting cervical 3-D CBCT images of 698 patients, which were examined for the presence and types of PP.

RESULTS

In 257 patients, 438 PPs, complete or partial, bilateral or unilateral, were identified on the 698 cervical 3-D CBCT scans; therefore, the prevalence was 36.8%. Bilateral complete PP and partial PP were observed in 6.3% and 16.2% of subjects, respectively. There was a significant difference in the prevalence between males and females (P = .001) and between the right and left sides between males and females, but not between age groups.

CONCLUSION

Ponticulus posticus is a relatively common anomaly in this Turkish sample, which may have implications for those who perform clinical procedures on the upper cervical spine.

Prevalence of ponticuli posticus among patients referred for dental examinations by cone-beam CT

BACKGROUND CONTEXT

Ponticulus posticus (PP) is the bony bridge that can completely or partially embrace the vertebral artery and the suboccipital nerve root at the atlas posterior arch. The PP can be a possible cause of vertigo, vertebrobasilar insufficiency, neck pain, shoulder pain, and cervicogenic headache. Moreover, the vertebral artery injury may happen during atlas lateral mass screw insertion in the presence of PP.

PURPOSE

The purpose of this study was to determine the prevalence of PP in a population of patients undergoing dental cone-beam computed tomography (CBCT) and the association between PP and atlas superior articular facet (SAF).

STUDY DESIGN

This is a retrospective study.

PATIENT SAMPLE

Five hundred consecutive patients who had undergone dental CBCT scans were included.

OUTCOME MEASURES

Outcome measures were age, sex, and radiologic measures.

METHODS

The maximum anteroposterior and transverse dimensions of atlas SAF were measured on the axial image, and then the area was calculated by using the formula for an elliptical area. The left-right differential ratios of the SAF in patients with unilateral PP were compared with those in age- and gender-matched patients without PP. The relationships among imaging findings, age, and sex were assessed with the two-tailed paired t test, χ(2) test, and logistic regression model, as appropriate.

RESULTS

The overall prevalence of PP was 7% (35 of 500 patients). There were no significant differences in the prevalence of PP with gender and age. The anteroposterior dimension, transverse dimension, and area of atlas SAF on the PP side were significantly larger than those on the non-PP side in the 18 unilateral complete PP patients (p<.001, p<.001, and p<.001, respectively) and in the 11 unilateral partial PP patients (p=.001, p=.007, and p<.001, respectively). The SAF area differential ratios in patients with unilateral PP were greater than those in the patients without PP (29.8% vs. 2.9%, p=.002 for 18 complete lesions, and 23.5% vs. 1.8%, p<.001 for 11 partial lesions).

CONCLUSIONS

The prevalence of PP and the measurement of SAF can be assessed by CBCT. The imaging findings show the larger SAF on the PP side and greater left-right difference of SAF area in the patients with unilateral PP.

Normal anatomy and anatomic variants of vascular foramens in the cervical vertebrae: a paleo-osteological study and review of the literature

We investigated 923 cervical vertebrae belonging to late-antiquity and medieval skeletal remains and assessed the qualitative and quantitative structural characteristics of transverse foramens (TF) and additional vascular canals. We also reviewed the pertinent literature. Double TF were chiefly observed in C6 (with a right/left side prevalence of 35.7 and 44.4%, respectively) and C5 vertebrae (23.6 and 23.9%, right/left side, respectively), while unclosed TF were mainly documented in C1 vertebrae (8.4%). Retrotransverse canal and retrotransverse groove were present in 8.5 and 17.8%, respectively, of C1 vertebrae examined, while arcuate foramens and supertransverse foramens were found in 7.3 and 3.7% of specimens, respectively. TF diameter decreased from C6 to C2 vertebrae, being smallest in C7 and greatest in C1 vertebrae, with no left/right significant difference. There was a significant correlation between TF diameter and stature, but only on the right side. The mean area of the arcuate foramen was lower than the mean area of the ipsilateral TF (24.5 ± 5.7 vs 28.5 ± 7.7 mm(2), respectively; p = 0.048), possibly causing compression of the vertebral artery within the arcuate foramen. The study of human vertebrae excavated from archaeological sites is a simple and effective way to analyze the morphology and quantitative anatomy of vascular foramens.

Retrospective analysis of ponticulus posticus in Indian orthodontic patients-a lateral cephalometric study

BACKGROUND

The lateral cephalogram is the most common diagnostic radiograph used in clinical orthodontics. Significant cervical spine pathology can be detected on the routine lateral cephalogram. The aim of this study is to sensitize clinicians for examining the cervical area of lateral cephalogram carefully and thus record anatomical variations.

MATERIALS AND METHODS

The presence and types of ponticuli posticus were investigated on 650 lateral cephalograms which were randomly selected from archived records at AECS Maaruti College of Dental Sciences & Research Centre, Bangalore.

RESULTS

The prevalence rate of Ponticulus Posticus in our study was found to be 11.1%. Though there was slight female predominance of 11.7% as compared to 10.4% in males, difference was not statistically significant.

CONCLUSION

Ponticulus posticus is a common anomaly in the Indian population. If any such anomaly is detected or suspected, it must be documented in the patient's health record and specialist consultation must be sought. The lateral cephalogram must thus be considered as one of the baseline screening tool for detecting anomalies and pathology in the cervical spine region.

A cone beam CT investigation of ponticulus posticus and lateralis in children and adolescents

OBJECTIVES

To determine the prevalence and pathogenesis of ponticulus posticus (PP) and ponticulus lateralis (PL) in children and adolescents.

METHODS

Cone beam CT scans of 576 patients were examined for PP and PL. The patients were divided into three age groups: 10 years and younger, 11-13 years and 14 years and older. Ponticulus formation was categorized as absent, partial or complete. Gender, race and location (right, left or bilateral) were recorded. Data were analysed with the χ(2) test, with significance at p < 0.050. Institutional review board approval was granted.

RESULTS

Overall prevalence of PP was 26.2%, with complete lesions in 10.4%. The frequency of PP was greater in patients aged 14 years and older (p ≤ 0.038). The occurrence of complete PP was greater in patients aged 11 years and older (p = 0.028). Lesions were more common in males (p = 0.014) and in blacks compared with other non-white races (p = 0.035). Bilateral PP was more common than right-sided lesions (p = 0.008) and more frequent in the oldest cohort (p = 0.006). Overall prevalence of PL was 6.1% (3.0% complete), with no differences between age groups, genders, races or by location.

CONCLUSIONS

PP is not uncommon even in the first decade and increases in frequency, completeness of calcification and numbers in mid-adolescence. It appears to be more common in males and in blacks. PP may be a congenital osseous anomaly of the atlas that mineralizes at various times. PL is less frequent with no demographic predilections.

Anatomic Consideration of the C1 Laminar Arch for Lateral Mass Screw Fixation via C1 Lateral Lamina : A Landmark between the Lateral and Posterior Lamina of the C1

OBJECTIVE

To clarify the landmark for deciding the entry point for C1 lateral mass screws via the posterior arch by using 3-dimensional (3D) computed images.

METHODS

Resnick insisted that the C1 posterior arch could be divided into pure posterior and lateral lamina (C1 pedicle). Authors studied where this transition point (TP) is located between the posterior lamina and the C1 pedicle and how it can be recognized. The 3D computed images of 86 cadaver C1s (M : F=45 : 41) were used in this study.

RESULTS

The superior ridge of the C1 posterior arch had 2 types of orientation. One was in the vertical direction in the C1 posterior lamina and the other was in the horizontal direction in the C1 pedicle. The TP was located at the border between the 2 areas, the same site as the posterior end of the groove of the vertebral artery. On posterior-anterior projection, the posterior arch was sharpened abruptly at TP. We were unable to identify the TP in 6.4% of specimens due to complete or partial osseous bridges. A total of 93.8% of the TP were located between the most enlarged point of the spinal canal and the medial wall of the vertebral artery.

CONCLUSION

The anatomic entry zone of C1 lateral laminar screws was clarified and identified based on the TP by using preoperative 3D computed images.

Prevalence of ponticulus posticus in Indian orthodontic patients

OBJECTIVES

The purpose of this study was to investigate the prevalence of complete ponticulus posticus in Indian orthodontic patients.

METHODS

The presence and types of ponticuli posticus were investigated on 858 lateral cephalograms.

RESULTS

Complete ponticulus posticus was found in 4.3% of the subjects studied with a male (5.33%) predominance over female in the population (3.76%).

CONCLUSIONS

Ponticulus posticus is not a rare anomaly and the patient must be told of the implications and importance of detecting ponticulus posticus on a lateral cephalogram. This information can prove beneficial for the diagnosis of head and neck symptoms later.

Anatomia do sulco da artéria vertebral

INTRODUÇÃO: Diversas técnicas cirúrgicas têm sido realizadas na região craniocervical devido a diversas patologias. Durante o acesso cirúrgico a essa região existe um risco potencial de lesão iatrogênica da artéria vertebral, relacionado ao acesso lateral amplo e à avaliação inadequada da anatomia local. Variações no trajeto da artéria vertebral ocasionam maior risco de lesão vascular. O estudo pré-operatório por imagem da anatomia da artéria vertebral e do seu sulco tem sido realizado para aumentar a segurança cirúrgica. OBJETIVO: Estudar a morfometria da artéria vertebral no atlas através da tomografia computadorizada do sulco da artéria vertebral (SAV) em 30 atlas isolados de cadáveres. MATERIAIS E MÉTODOS: O SAV e suas relações com a linha média foram avaliados através de oito medidas lineares e duas angulares, bilateralmente. A média, valor máximo e mínimo, e desvio padrão foram calculados para cada parâmetro. RESULTADOS: O SAV apresentou uma maior largura e maior espessura do lado esquerdo (p<0,05) CONCLUSÃO: os nossos dados sugerem que a dissecção posterior e superior do arco posterior devem permanecer a uma distância lateral de 11,2mm e 7,4mm da linha média para que haja segurança no procedimento.

Is mechanical deformation of the suboccipital vertebral artery during cervical spine rotation responsible for vertebrobasilar insufficiency?

PURPOSE

The atlanto-axial region of the vertebral artery (VA) has traditionally been considered at risk for injury during cervical spine rotation, leading to compromised blood flow to the hindbrain and vertebrobasilar insufficiency or ischaemia (VBI). The anatomical relationships of the suboccipital VA (VA3) and related haemodynamic changes associated with cervical spine movements have been neglected, however. The present review aims to provide a new perspective on possible causes of reduced blood flow to the hindbrain, with particular reference to the functional anatomy of VA3 and related biomechanics of cervical spine rotation, to inform evidence-based practice.

METHOD

To support the hypothesis that it is VA3, not the VA in the atlanto-axial region, that is compressed or stretched during cervical spine rotation, current studies of blood flow changes in the VA distal to the region of rotation and possible arterial deformation were retrieved, using AMED, CINAHL, Embase, Pedro and PubMed, and reviewed.

RESULTS

Possible sites for VA3 deformation, based on a re-examination of its anatomy and biomechanics, are described. However, no research reports of VA3 blood flow measurements associated with cervical spine rotation have been published to date. Five studies on blood flow changes in the intracranial VA after cervical spine rotation were reviewed. The subjects for four of these reports were young, healthy individuals, and the fifth included older patients and young non-patients. The analysis of these studies demonstrated that more rigorous control of variables is necessary before meaningful conclusions can be made.

CONCLUSION

The paucity of studies of VA3 emphasises the need for research based on informed understanding of the anatomy and biomechanics of this area. This view on mechanical deformation of VA3 associated with cervical spine rotation as a possible cause of compromised blood flow to the hindbrain and VBI provides further argument for avoiding full-range or sustained cervical spine rotation in clinical practice.

Foramen arcuale: anatomical study and review of the literature

Object

The neurosurgical literature is lacking information on the so-called foramen arcuale. When this foramen is present, the vertebral artery (VA) travels through it after exiting the transverse foramen of the atlas and prior to entering the cranium.

Methods

The authors performed a study in 60 cadavers to determine the incidence of the foramen arcuale and ascertain morphometric information on its anatomy. In specimens in which the foramen arcuale was observed, the authors studied the relationship between it and the VA.

The authors identified a foramen arcuale in 5% of specimens. The mean length and thickness of the osseous struts that converted the groove for the VA into the foramen arcuale were 7.0 and 2.0 mm, respectively. The mean area of the identified foramina was 14.2 mm2. The mean area of the ipsilateral C-1 transverse foramina was 18 mm2 in specimens with a foramen arcuale. The mean measurements of the proximal, intraforaminal (foramen arcuale), and distal diameter of the V3 segment of the VA at the level of the foramen arcuale were 6, 4, and 5 mm, respectively. In all specimens the authors noted that the intraforaminal part of the V3 segment was grossly compressed.

Conclusions

The authors found that the foramen arcuale may compress the V3 segment of the VA. Based on their postmortem study, however, they cannot conclude that compression at this location results in symptomatic VA insufficiency. Based on their review of the literature, it seems that symptomatic compression of the VA at this location may be alleviated in some patients with decompressive procedures.

Posterior ponticles and rotational stenosis of vertebral arteries. A pilot study using Doppler ultrasound velocimetry and magnetic resonance angiography

OBJECTIVE

To determine whether the presence of posterior ponticles markedly increases by 30% or more, the incidence of major rotational stenosis of vertebral arteries.

METHODS

Doppler ultrasound studies were performed in 3 private chiropractic clinics and in the radiology department of a public hospital, and magnetic resonance angiography (MRA) studies were made in the latter location. Thirty-two chiropractic patients had Doppler velocimetery, and 16 of these patients had MRA scanning. The outcome measures included changes in Doppler velocimetry signals and MRA images indicative of marked rotational stenosis of vertebral arteries.

RESULTS

All vertebral arteries from the 32 patients displayed no signs indicative of marked rotational stenosis.

CONCLUSION

The findings of this study show that the incidence of major rotational stenosis of vertebral arteries is not markedly increased by the presence of posterior ponticles.

Radiographic anomalies that may alter chiropractic intervention strategies found in a New Zealand population

OBJECTIVE

To provide occurrence rates for anomalies discovered on radiographs in patients seeking chiropractic care.

METHODS

One thousand four random patient files dated between 1997 and 2001 were obtained from the records of the outpatient clinic at the New Zealand College of Chiropractic. In cases in which radiographs were taken, the radiographic reports were analyzed by the authors for the presence of a number of anomalies.

RESULTS

Eight hundred forty-seven full-spine radiographs were included in the study. Anomalies were found in 68% of patients who had radiographs taken. The 5 most frequently occurring anomalies in descending order were degenerative joint disease (23.8%), posterior ponticle (13.6%), soft tissue abnormalities (13.5%), transitional segments (9.8%), and spondylolisthesis (7.8%). Other noteworthy occurrences because of their generalized status as absolute contraindications to adjustment are fracture (6.6%), malignant tumor (0.8%-3.1%), abdominal aortic aneurysm (0.8%) and atlantoaxial instability (0.6%).

CONCLUSION

A large percentage of patients presenting for chiropractic care have anomalies present on spinal radiographs. Further research and analysis is necessary to investigate the risk-verses-benefit ratio of spinal radiographs for chiropractic patients.

The vertebral artery: a review of anatomical, histopathological and functional factors influencing blood flow to the hindbrain

An uncompromised blood flow to the brain is essential for normal neurological function. If the blood supply to the hindbrain, via the paired vertebral arteries, is reduced sufficiently, signs and symptoms of tertebrobasilar ischaemia may result. There are several factors that may cause a reduction in vertebral artery blood flow. These include exostoses, such as the retroarticular canal and lateral bridge of the atlas vertebra that may cause compression of the related part of the vertebral artery; or atherosclerosis of the artery wall occluding the vessel lumen. Functional factors, such as sustained end-of-range rotation of the cervical spine, may cause distortion of the vertebral artery in the suboccipital region, which may be reflected as decreased blood flow in the suboccipital and intracranial parts of the artery. A combination of such factors is likely to cause reduced blood flow to the hindbrain. It is the purpose of this review to highlight some of the factors that may compromise vertebral artery blood flow and, therefore, to provide some evidence on which to base our professional practice.

Bony ponticles of the atlas (C1) over the groove for the vertebral artery in humans and primates: Polymorphism and evolutionary trends

The aim of this study was to ascertain the distribution in primates of the three possible bony ponticles over the groove for the vertebral artery (ventral, lateral, and dorsal ponticles), in order to attempt to understand the variants observed in humans and to ascertain possible evolutionary trends in primates. The material consisted of 393 atlases of extant nonhuman primates representative of 41 genera, and of 500 human atlases (dried bones of adults). For each atlas, we studied the existence and morphology of the ponticles, and the type of association of these three ponticles on a given side, which are theoretically of eight in number (types A-H). The occurrence of these ponticles varied from complete absence to constant presence, according to the genera and taxa of primates. The presence of each of these ponticles in primates can be interpreted as a primitive or plesiomorphic character, and their absence as a derived or apomorphic character. The strepsirhines-platyrrhines-cercopithecines group, presenting a predominant primitive pattern (type A), appeared to be separated from the colobines-hominoids group, presenting predominant derived patterns (type C in colobines, Pongo pygmaeus, and Pan troglodytes, and the more derived type D in Hylobates, Gorilla gorilla, and Homo sapiens). The last derived stage, corresponding to the disappearance of the three atlantal ponticles (type H), was only observed in some individuals in hominoids. A marked intraspecific polymorphism characterized the hominoids. The presence of lateral and dorsal ponticles in humans appeared to correspond to their persistence within the progressive disappearance of the atlantal ponticles, constituting an evolutionary tendency characteristic of primates and particularly of hominoid evolution.

On unknown bone bridge and foramen of the atlas

The atlas of a 52-year-old male Japanese cadaver, which had been removed and macerated, presented a bilateral unknown bone bridge forming a foramen (Case 1). The bone bridge connected the ponticulus lateralis (PL) and posterior (PP) to form an oval foramen between the superior roots of both ponticuli. The atlas of a 69-year-old male Japanese cadaver was found to have similar variations in situ (Case 2). In this case, the right bone bridge connected the superior root of the incomplete PL and the inferior root of the also incomplete PP to form a long ellipsoid foramen opening medially. The medial opening of the foramen was closed by a ligamentous connective tissue in situ. The condylar emissary vein passed this complete foramen to join the cervical epidural venous plexus. The similar bilateral foramen in case 1 was supposed to pass the same vein as in case 2. The bone bridge between the two ponticuli and the resulting foramen mentioned above have not been described previously, as far as we know. We propose that these structures be called the ponticulus interponticularis atlantis and the foramen atlantoideum interponticulare, respectively.

Incidence of ponticulus posterior of the atlas in migraine and cervicogenic headache

BACKGROUND

The clinical significance of the ponticulus posticus is far from clear. It has been associated with headaches, Barré-Lieou syndrome, photophobia, and migraine. However, little epidemiologic evidence for this exists.

OBJECTIVE

This study investigated the relationship of ponticulus posticus on x-ray studies and headache symptoms in a series of chiropractic patients.

METHODS

Eight hundred ninety-five patients who visited a chiropractic clinic for the first time and whose conditions required cervical spine x-ray examinations were studied. Complaints were categorized as migraine with aura, migraine without aura, cervicogenic headache, neck pain only, and other conditions. The presence or absence of the ponticulus posticus (whether partial or complete) was determined by means of a lateral cervical film and noted as a positive or negative finding. The data were analyzed by frequency analysis and Pearson's chi 2 test.

RESULTS

Forty-six percent of the sample were men and the predominant complaint was neck pain (33%). Most patients were in the fourth decade of life. The frequencies of the other complaints were migraine with aura (7%), migraine without aura (4%), cervicogenic headache (22%), other conditions (33%). An 18% prevalence of ponticulus posticus was found. This finding was significantly associated with migraine without aura (chi 2 = 4.97; P = .03) and not with any other conditions.

CONCLUSION

In a chiropractic patient population that required cervical x-ray examinations, a significant association was found between ponticulus posticus and migraine without aura, with an odds ratio of 2.19:1 in favor of this complaint being present with the osseous anomaly. The mechanism for this remains obscure but may be related to ischemic compression of the vertebral artery or by dural tension at the craniocervical junction.

Microsurgical anatomy of the atlantal part of the vertebral artery

BACKGROUND

Microanatomy of the vertebral artery has been the subject of multiple studies. However, none of them has covered every aspect of microvascular anatomy of the atlantal part of the vertebral artery.

MATERIALS AND METHODS

Microsurgical anatomy of the atlantal part of the vertebral artery was studied in 14 cadaveric specimens. The artery was dissected using the standard microsurgical technique under operative microscope magnification. The atlantal part of the vertebral artery was divided into five segments: the foraminal, sagittal, transverse, medial condylar, and dural. The length of each segment was measured, as was the diameter of the artery. The branches of this part of the artery were identified and the distance between the point of dural entry of the artery and the midline of the atlanto-occipital dura was measured. Distance between the mastoid tip and the artery and the distance between the mastoid tip and the tip of C1 transverse process were measured.

RESULTS

Results of all measurements are summarized in tables and text. We discuss various anomalies, branches, and lesions of the vertebral artery and surgical approaches with new methods of managing diseases in this area.