Silviya Nikolova

Multiple Wormian bones and their relation with definite pathological conditions in a case of an adult cranium.

Wormian bones, also known as intrasutural bones, are present as an anatomical variation in healthy individuals. However, a higher than the usual incidence can be an important feature of some congenital pathological conditions. In this study we describe a case of an adult cranium with multiple Wormian bones. The cranium was a single sample obtained from an archaeological excavation in Vinitsa, Northeastern Bulgaria, and probably dated in the Chalcolithic. The Chalcolithic is a period of human history connected with discovering and using of copper. Actually, it is a transitional phase between the Neolithic and the Bronze Age. In this case the Wormian bones are mostly large in size and arranged in a mosaic pattern in several cranial regions. The cranium also shows features such as dolichocrany, a moderate platybasia, a notch in the posterior margin of the foramen magnum, hypoplastic and asymmetrical frontal sinuses, underdeveloped mastoid air cells, hyperostosis cranii interna, moderate frontal bossing, a complete metopic suture, a delayed sutural closure, relatively small facial bones, an early loss of teeth, dental caries and hypoplastic enamel defects on two preserved molars. Differential diagnosis indicates that the combination of all these features shows a link with pathological conditions involving dysplasias with prominent membranous bone involvement and an increased bone density such as cleidocranial dysplasia and pyknodysostosis.

Absence of foramen spinosum and abnormal middle meningeal artery in cranial series.

In comparative and evolutionary aspects in humans, the middle meningeal artery enters the cranium through the foramen spinosum, whereas in great apes the middle meningeal artery can enter the cranium through foramen spinosum, through foramen ovale or through petrosphenoid fissure. Generally, in nonhuman primates the anterior meningeal system is associated with the ophthalmic branch of the internal carotid artery. The vessels joining the two systems pass through the additional channels: the superior orbital fissure or through the cranio-orbital foramen. In anatomically modern humans, the absence of foramen spinosum involves abnormal development and course of the middle meningeal artery and it is usually accompanied with replacement of the conventional middle meningeal artery with such, arising from the ophthalmic artery system. In these cases the middle meningeal artery most often enters the middle cranial fossa through the superior orbital fissure and rarely through the meningo-orbital foramen. All skulls, investigated in the present study, belonged to adult individuals of both sexes, conditionally grouped into three cranial series--contemporary male, medieval male, and medieval female series. The absence of foramen spinosum was established only among the medieval male and female series--in 1 (0.70%) male and in 1 (0.72%) female skull on the right side and in 3 (2.13%) female skulls on the left side. In 1 (0.72%) female skull, a small atypically located foramen spinosum was established on the right side. In all of the described cases, the intracranial meningeal grooves started from the lateral edge of the superior orbital fissure and probably reflect the ophthalmic origin of the middle meningeal artery.

Digital radiomorphometric analysis of the frontal sinus and assessment of the relation between persistent metopic suture and frontal sinus development

OBJECTIVES This study aimed to establish the frequency of the frontal sinus (FS) aplasia, to compare metopic and nonmetopic series and thus to assess the relationship between the preservation of metopic suture and FS development. MATERIALS AND METHODS FSs were investigated in 230 dry skulls of adult males distributed into control (137) and metopic (93) series. They were visualized through industrial digital radiography. RESULTS In the control series, the FS aplasia was observed in 12.41% of the skulls, and it was mostly unilateral (8.76%) than bilateral (3.65%). The left-sided aplasia (5.11%) slightly prevailed over the right-sided one (3.65%). In the metopic series, the aplasia was observed with a frequency of 19.35%, and the bilateral aplasia (7.53%) was rarer that the unilateral one (11.83%), while the right-sided aplasia was clearly predominant (9.68%) compared to the left-sided one (2.15%). DISCUSSION The significant differences between both series showed a tendency for the persistence of metopic suture to be frequently related with FS underdevelopment in the vertical plate of the frontal bone, but in cases of pneumatization, it was preferentially on the left side. Taking into account that the cranial hypertension leads to suture diastasis and hinders development of the FS, it could be suggested that persistence of the metopic suture along with underdevelopment of the FS in nonsyndromic adults could be an expression of an elevated intracranial pressure during early development as an after-effect of certain condition.

Morphometric study of the mylohyoid bridging in dry mandibles

ABSTRACT The mylohyoid bridging is a hyperostotic variation representing formation of bony bridges over the mylohyoid groove. The goals of this study were to establish the frequency of mylohyoid bridging in contemporary and medieval series from Bulgaria and to examine the changes in the prevalence through time, to assess and compare the different types of mylohyoid bridging, to establish the patterns of distribution with respect to laterality, sex and age and to accomplish a morphometric analysis. Materials and methods: The study was performed on a total of 448 intact dry mandibles of adult individuals from both sexes, grouped into contemporary male, medieval male and medieval female series from Bulgaria. The individuals in the series were distributed into two age cohorts: between 20-40 years old and above 40 years. Мacroscopic, metric and statistical analyses were performed. Results and Conclusions: The frequency of the mylohyoid bridging was 10.99% (21 out of 191 mandibles) for the contemporary male series, 9.45% (12 out of 127) for the male series and 7.69% (10 out of 130) for the medieval female series. The comparison between both male series indicated slightly increasing of the mylohyoid bridging with time. No significant bilateral and sex differences in the frequency and pattern of distribution of the mylohyoid bridging were established. The most common type of bridging was the distal one. The dependence of the mylohyoid bridging on the aging is controversial since in the female series its frequency was significantly higher in the individuals over 40 years, while in both male series it did not differ considerably between the age groups. The metric analysis did not show significant differences between the male series. However, the sexual differences were noteworthy with respect to the whole length of the mylohyoid groove and the distance between the bridge and the distal point of the mylohyoid groove. Furthermore, the considerable differences between the metric characteristics of lingular and distal type showed that this approach is useful and could be applied for precise differentiation of the mylohyoid bridging types. During the investigation, we also observed several cases of an accessory groove in the region of the mylohyoid groove. This additional groove most probably reflects variations in the branching patterns of the inferior alveolar nerve and/or mylohyoid nerve and could be of importance in oral surgery and dental practice.

Morphology of suprascapular notch in medieval skeletons from Bulgaria.

The suprascapular notch is situated in the lateral part of the superior border of the scapula, just medial to the base of the coracoid process, giving passage for the suprascapular nerve. The aim of this study is to determine the frequency of different types of suprascapular notch in male and female medieval skeletal series and to assess the sexual differences. The shape of the notch was classified into 5 types, based on the scheme given by Alekseev. A total of 102 scapulae and scapular fragments were investigated. The results show that the deep notch was the most common. In the left female scapulae the shallow notch was frequently observed as well. Three cases of suprascapular foramen, which is considered as a risk factor for suprascapular nerve neuropathy, were observed and there was a double foramen in one of them, which is a very rare case. According to the results of c2 test, there were no significant sexual differences in the distribution of notch types. Our results illustrate that there were some individuals among the investigated medieval population potentially affected by suprascapular nerve entrapment syndrome and their way of livingmay have been impacted by the symptoms accompanying this condition.

Variations in the squamous part of the occipital bone in medieval and contemporary cranial series from Bulgaria.

The squamous part of the occipital bone is a place of many different variations. They are a result of faulty ossification in the occipital squama or due to the presence of sutural bones in the lambda region. As their differentiation is intricate because of the various criteria used, the issue of their recognition in the adult skull still remains difficult even though they can be clearly distinguished at a younger age. The aim of the present study was to compare the frequency of interparietal, preinterparietal and sutural bones in the lambda region in medieval male and female cranial series as well as between medieval and contemporary male series from Bulgaria. We also discuss the development of the occipital squama in order to set clearer criteria for further differentiation of such variations in the adult skull. In the reviewed 3 cranial series, the variations in the squamous portion of the occipital bone were observed with a low frequency. The incidence of preinterparietal bones was more common than the interparietal ones. The sutural bones in the lambda region were numerous in the series. No statistically significant sex or intergroup differences were established. So even if these anatomical variations are relatively rare, the understanding of them is of significance for many disciplines like anthropology, comparative and developmental anatomy, clinical and forensic medicine.

Sex estimation by size and shape of foramen magnum based on CT imaging

Foramen magnum (FM) has a well-protected position, which makes it of particular interest in forensic research. The aim of the study is to assess the sex differences in size and shape of FM, develop discriminant functions and logistic regression models based on the FM measurements, compare the accuracy results of the measurements obtained through different measuring approaches, and establish the most reliable variables for sex estimation in Bulgarian adults. Head CT scans of 140 Bulgarian adults were used in the study. The segmentation of the skulls was performed in the software InVesalius. The length, breadth, circumference, and area were measured based on the 3D coordinates of definite landmarks and semi-landmarks. The circumference and area were calculated regarding the foramen as a 2D and 3D structure. Two additional variables (λ2 and λ3) corresponding to the least square errors along the length and breadth directions at the fitting of the 3D coordinates to a plane were examined for their sex discriminating ability. The FM shape was classified based on the values of the FM index. The significance of the sex differences was assessed. Discriminate function analysis and binary logistic regression were conducted. Significant sex differences were established in the FM size and shape. The eigenvalue λ3 is the best discriminating parameter applying discriminant function analysis. The acceptance of FM as a 2D or 3D structure does not provide substantial information for its sex discrimination. The measurements of FM do not offer sufficiently high predicting rates for sex estimation in the Bulgarian population.

Accuracy of Linear Craniometric Measurements Obtained from Laser Scanning Created 3D Models of Dry Skulls

The aim of this study was to establish the reliability of directly taken linear measurements on dry skulls and corresponding measurements taken on the 3D digital models created by laser scanning as well as to assess the agreement between both measuring methods. Four skulls were measured in two competitive methods—a direct measuring, based on the conventional craniometric method, and a digital measuring, accomplished on 3D models created by laser scanning. Thirteen cranial measurements were taken on both dry skulls and 3D models. The intra- and inter-examiner reliability was estimated using intraclass correlation coefficient. The agreement between both measuring methods was assessed applying the Bland-Altman method for replicated measurements. A Bland-Altman plot was constructed for each of the 13 parameters. The 3D model and directly taken measurements were assessed as highly reliable and reproducible, excepting the orbital height. Our results showed that 96 % of all digital measurements differ from the directly taken ones with less than 2 mm and respectively 67.6 % differ with less than 1 mm. Based on the results of the Bland-Altman plots, most of the measurements obtained by both measuring methods could be accepted as comparable, since the majority of differences were within the constructed limits of agreement. However, there were digital measurements, particularly these with landmarks situated on bone margins, which systematically overestimated the directly taken ones.

Incidence of a Bifid Mandibular Condyle in Dry Mandibles

Background: A bifid mandibular condyle (BMC) is a rare anatomical variation with an etiology not fully understood. Although there are numerous case reports regarding it, purposeful epidemiological investigations on the BMC frequency among different groups are scarce. This study aims to investigate the incidence and laterality of BMC among series of adult males from Bulgaria and perform a morphometric analysis of it. Materials and methods: A series of 500 dry intact mandibles from adult males was investigated. The condyles were macroscopically observed and when skulls were available, the corresponding mandibular fossae were also inspected. In the cases when bifid condyles were found, 27 measurements were taken. Results: Bifid mandibular condyle was observed in 4 (0.8%) mandibles. All of the cases were unilateral, 2 on the right side (0.4%) and 2 on the left (0.4%). The condyles were divided into medial and lateral heads by a sagittal fissure or a notch. Conclusion: The established frequency of BMC was comparable with those reported in Turkish and Korean populations. The lack of injury marks and traces implies a developmental etiology of this condition.

Reliability and Accuracy of Angular Measurements on Laser Scanning Created 3D Models of Dry Skulls

The aim of the study was to assess the accuracy and reliability of skull angles measured on 3D models created by laser scanning. Five skulls were measured through both conventional and digital measuring methods. The 3D models were created using a hand-held laser scanner Creaform VIUscan™. Seven angular characteristics were measured three times by two observers. The intra- and interobserver reliability were assessed using intraclass correlation coefficient. The differences between the digital and direct measurements were assessed using the measurement and relative errors. The intraclass correlation coefficients for digitally taken angles indicated almost perfect intra- and interobserver reliability, except for the alveolar profile angle showing moderate interobserver agreement. The overall measurement error based on the differences between digitally and directly measured angles was 0.61° and the relative error was 0.68%.