2020, Number 3
Prevalence of ponticulus posticus classification in patients from 9 to 25 years of age in a population in Cuenca-Ecuador
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Language: English/Spanish [Versión en español]
References: 27
Page: 178-185
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ABSTRACT
Objective: To determine the prevalence of ponticulus posticus in lateral digital skull radiographs. Materials and methods: We randomly select Digital lateral skull radiographs from the database of an oral and maxillofacial radiology center in the city of Cuenca-Ecuador, of patients between 9 and 25 in 2013-2015. We calculate general and sex prevalences of ponticulus posticus according to the Cederberg and Stubbs classification. We performed multivariate multinomial regression analysis to compare the association between age and sex with the ponticulus posticus class 2, 3, and 4 compared to class 1. The data obtained were analyzed in the STATA V13.0 program. Results: One thousand lateral digital radiographs of the skull were analyzed, the average age was 15 (± 4.23) years, and 57.60% (n = 424) were women. The prevalence of class 1 was 71.8% (95% CI 68.92-74.51), class 2 was 16.5% (95% CI 14.32-18.94), class 3 was 5.5% (95% CI 4.24-7.10) and class 4 was 6.20% (95% CI 4.86-7.88). According to the multivariate analysis, we observed that men had a greater possibility of having a class 2 or 3 than class 1, while older patients were class 4 compared to class 1. Conclusions: Ponticulus posticus is an anatomical variant with a high prevalence in the studied population. According to the Cederberg and Stubbs classification, and due to its clinical importance, we found a higher prevalence of class 1 of ponticulus posticus. We observed that the calcification extends less than halfway through the vertebral artery. Men presented a higher prevalence of in class 2, so sex influences this anatomical variation. We observed that increasing the frequency of class 4 was associated with increasing age increased. We considered type 1 of the same classification was not clinically important since no calcification of any kind was observed.INTRODUCTION
Ponticulus posticus has been considered as a simple anatomical variant at the level of the cervical vertebrae, which generates the compression of the nervous and vascular structures that pass through the foramen such as the vertebral artery, the periarterial plexus, and the suboccipital nerve;1-3 which generates an occlusion of the vertebral artery that generates a vertebrobasilar insufficiency which generates vertigo,4-9 in addition to other symptomatology such as tension-type migraine, neuralgia of various types and even migraines without aura, it has also been related to neck and shoulder pain.5-7,10-12 It has been suggested that the ponticulus posticus and the vertebral artery play an important role in the genesis of arterial dissection and stroke in children due to the immobilization of the vertebral artery within it.13
The ponticulus posticus, described by Allen,14 is a bony arch that connects the retroglenoid tubercle located posterior to the superior articular fossa of the atlas with its posterior arch that originates the calcification of the lateral segment of the posterior atlantooccipital ligament or the capsule of this joint2,5 and is responsible for 50% of head movements.9 Clinically it is associated with the posture known as "turtle neck", and audible sounds during head movements.13 The ponticulus posticus is also known as "Kimmerle's Variation" (Kimerle, 1930), "superior retroarticular foramen" (Brocher, 1955), "Canalis vertebralis" (Wolff-Heidegger, 1961), "retroarticular ring of the vertebral artery" (Lamberty & Zivanovic, 1973), superior retroarticular foramen, sagittal foramen, posterior glenoid process, among others.2,5,7,10,14-17
Its etiology is attributed to an activation of the osteogenic potential in the cranial junction zone5 or by a development of the dorsal arch of the proatlas.4,18-20 A higher frequency has been reported in black males.2,19,21 It is important to know the prevalence of ponticulus posticus in the Latin population, the prevalence reported in other populations varies from 2 to 10%,2,5,6 and usually only be performed in populations with migraine symptoms; since this can guide us towards the diagnosis of several syndromes, such as Barre-Lieou or Eagle's syndrome; also generate a false preoperative impression at the time of placement of the fixation screws and perforate this structure and cause damage to the vertebral artery.16,18,22 Additionally, to our knowledge, no study has performed a multivariate analysis to identify possible associations between age, sex, and the categories of the modified Cederberg and Stubbs classification described in the study of Geist et al.1
MATERIAL AND METHODS
A descriptive cross-sectional study was carried out, whose study population was obtained from a radiographic archive of a radiological center in Cuenca-Ecuador, which consists of a total of 10,000 digital lateral cephalic teleradiographies, using a J. MORITA radiographic equipment. Veraviewepocs®. Model: X550CP-DC-UL. Serial number: 4531.
The sample size was estimated considering a prevalence of 50%, with a precision of 3%, a confidence level of 95%, and considering the total sample of 10,000 teleradiographies. The total sample was 1,000 lateral cephalic teleradiographies that were selected by a random selection method; the sample selection was performed using the "sample" command of the STATA V.13.0 program with which the 1,000 teleradiographies were selected. The inclusion criteria were: digital lateral skull teleradiographies from the radiology center taken in the years from 2013 to 2015, of both sexes and ages between 9 and 25 years, in which up to the sixth cervical vertebra was observed. To maintain the confidentiality management of the information, the names of the patients were omitted.
The degree of calcification of the atlanto-occipital ligament through the vertebral artery was observed to proceed to classify the teleradiographies into class 1, 2, 3, or 4 according to the classification of Cederberg and Stubbs.
In the first instance, the examples of the classes observed in the radiographs are shown in Figure 1. The participants were calibrated by a specialist in orthodontics, an expert in the subject, who acted as the gold standard. The measurements were taken on two occasions with an interval of one week, using 50 lateral cephalic teleradiographies with the double randomized method, comparing the data of the researchers against the specialist. Sensitivity and specificity values are reported for each Cederberg and Stubbs classification category and each of the evaluators; class one was the reference category (Table 1).
Once the standardization had been carried out, a digital record was kept and the data were subsequently entered into the STATA V13.0 statistical program, and the prevalences and their confidence intervals were calculated, and a test of proportions was used to compare whether there were statistically significant differences between the classes and sex. A multivariate multinomial regression analysis was performed to compare the association between age and sex to ponticulus posticus class 2, 3, and 4 in comparison with class 1. Table 2 shows the description of the ponticulus posticus classification according to the classification of Cederberg, Stubbs, et al.
RESULTS
According to the Cederberg and Stubbs classification in the whole sample, the prevalence of ponticulus posticus was 71.8% (95% CI 68.9-74.5), 16.5% (95% CI 14.3-18.9), 5.5% (95% CI 4.24-7.1) and 6.2% (95% CI 4.86-7.88) for class 1, 2, 3 and 4, respectively, as shown in Table 3. Regarding sex, in the bivariate analysis, it was observed that class 1 was significantly (p < 0.05) more frequent in women (76.91%; 95% CI 73.28-80.18) than in men (64.86%; 95% CI 60.18-69.27). In the other classes, no significant differences were observed between sex and prevalences in the remaining classes.
In the results shown in Table 4 of the multivariate multinomial analysis, in which class 1 was used as the comparison or reference category; it was observed that men had a 1. 55 (relative risk ratio (RRR) = 1.55; 95%CI 1.10-2.18; p = 0.012) and 4.73 (RRR = 4.73; 95% CI 2.53-8.84; p < 0.001) more likely to have class 2 and class 3, respectively than women compared to what was observed with class 1. In contrast to what was observed with class 4, where no association with sex was identified; but a directly proportional relationship with age was identified, the more the age increased, the more the probability increased (RRR = 1.07; 95% CI 1.01-1.13; p = 0.032) of presenting a class 4 in comparison with what was observed in class 1.
DISCUSSION
According to the classification of Cederberg and Stubbs,1,5,23 class 1 was the most frequent which agrees with that reported by Saleh,24 however, the prevalence of class 4 reported in the present study is less than 16.24 The data obtained from the Indian population report a low prevalence of ponticulus posticus of 2.2%,2 while that of 9.8% in agreement with that reported by Mitchell et al. 1998, which was carried out in African cadavers. The study conducted by Gibelli in the Italian population shows a result of 7.7% in the complete form of classification and 9% in the incomplete form.25 Kendrick and Biggs report a prevalence of 15.8% of the presence of ponticulus posticos without specifying the type of it. Geist, in the study conducted in Detroit, showed a higher prevalence of class 3 with 15.8%, followed by class 4 with 10.4%.1
No statistically significant difference by sex was determined, except for class 1, however, in the multivariate analysis it was possible to observe a greater possibility of being class 2 and 3 in the case of men compared to what was observed in class 1, this relationship was not observed in class 4. These results contrast with those reported by Kendrick and Biggs21 and Gibelli25 in patients aged 6 to 17 years where they reported that sex was associated with prevalence. However, recent studies1,2,21,26 have reported that the prevalence is higher in males, which is in the same direction as the results of the present study; since an increase in prevalence was observed in males of 55% (RRR = 1.55; 95% CI 1.10-2.18; p = 0.012) and 373% (RRR = 4.73; 95% CI 2.53-8.84; p < 0.001) compared to that observed in class 1.
Paraskevas points out that the prevalence of ponticulus posticus is related to age reporting progressive mineralization of the posterior arch of the atlas generating a partial or complete ossification27 which is consistent with the results of the multivariate model where it is observed that the older the age increases the prevalence of class 4 increases by 7% (RRR = 1.07; 95% CI 1.01-1.13; p = 0.032) compared to what was observed in class 1. However, cases of complete ponticulus posticus have been reported in children under 10 years of age, even in our study cases of complete ponticulus posticus were found in 9-year-old children suggesting that this variation is independent of age, nor can it be related to degenerative changes since there is a high prevalence of complete ponticulus posticus in young populations, therefore it is suggested that this anatomical variant is not synonymous with aging or a hypertrophic process.23,25,26
LIMITATIONS AND STRENGTHS OF THE STUDY
One of the limitations of the study is that in the present study there was no information related to ethnicity or additional sociodemographic information. Although the vast majority of studies do not report an assessment of concordance (Kappa coefficient), the main limitation of the study is the inter-operator concordance; since one of the evaluators had low reliability in comparison with a specialist. However, this can be considered acceptable due to the great overlapping of radiographic structures, which represents a weakness of the radiographic method used, observed in the area to perform this measurement.
Regarding the strengths of the study, it should be emphasized that the sample size was sufficient to determine the prevalence with an accuracy of less than 3%. Another strength is the random selection of the sample, which supports the validity of the sample and its representativeness to the study population. An additional element, which has not been observed in previous studies, is the inclusion of multivariate multinomial regression analysis, where it was possible to explore the effect of sex and age to the greater probability of presenting a class 2, 3, or 4 in comparison with that observed in class I patients.
CONCLUSIONS
Cederberg and Stubbs class 1 was the most prevalent in both men and women, known as the absence of ponticulus posticus, followed by class 2 and 4. It is important to note that both evaluators had sensitivity and specificity values higher than 95% for classes 3 and 4, despite having a low prevalence. The lowest values were observed for sensitivity; from 33.3 to 63.2%; these values suggest an underestimation in the prevalence of class 2; and in the same sense, the values for class 2 would be underestimated in comparison with class 1; without this representing any significant change for classes 3 and 4.
The results of the present study show that class 3 was the least prevalent in the whole study. Sex influences the presentation of this anatomical variation because males present a higher percentage of this anatomical variation in classes 2 (18.7%), 3 (9.7%), and 1 (6.4%) than females.
The knowledge of the ponticulus posticus contributes to an integral formation of the dental student because when diagnosing this anatomical variant in our patients, adequate management is recommended, avoiding hyperextension movements of the neck during dental care, since this would generate compression of the vertebral artery.
Oral radiologists and oral health professionals should observe in imaging studies both the head and neck in detail to find any anatomical variant or pathology. That is why a proper observation has been considered of vital importance since it will allow the identification of the ponticulus posticus.
REFERENCES
AFFILIATIONS
1 Residente de la Especialidad de Rehabilitación Oral, Universidad de Cuenca, Ecuador.
2 Odontóloga de Practica Privada, Cuenca, Ecuador.
3 Residente de la Especialidad de Ortodoncia, Universidad de Cuenca, Ecuador.
4 Docente de la Facultad de Odontología, Universidad Católica de Cuenca, Ecuador.
5 Profesor, División de Estudios de Posgrado e Investigación, Facultad de Odontología, UNAM, México.
6 Docente de la Facultad de Odontología, Universidad de Cuenca, Ecuador.
CORRESPONDENCE
Vinicio Barzallo-Sardi. E-mail: vinicio.barzallo@ucuenca.edu.ecReceived: Agosto 2021. Accepted: Marzo 2022.