Craniofacial aysmmetries and dysmorphosis.

"Craniofacial asymmetries and dysmorphosis. Craniofacial architectural analysis of La Queue-en-Brie (Val-de-Marne, Ile-de- France) medieval populations." In Val-de-Marne, hundreds of anthropological remains from many necropolis have been uncovered. Our topic is about the ones of La Queue-en-Brie’s Saint Nicolas church. The age of this area is set between 890 and 1638 (respectively – 1114 and – 366 B.P.) by Carbon 14 analysis. A large number of the 251 skeletons exhumed in La Queue-en- Brie show cranio-facial disharmonies with various types of asymmetries. The several causes of these asymmetries are : craniostenosis, pseudo-plagiocephaly, torsion, lateral bending rotation … The effects of craniostenosis develop also some asymmetries that may lead to malocclusions. Why are we observing such phenomena ? From the fetal stage and for the whole growth, children crania will evolve according to the strains they are submitted to, what may result in cranio-facial architectural changes and also in dental malocclusions. With the presence of a malocclusion one can infer that possibly craniofacial morphogenesis went abnormally. Medical studies tend to link observed abnormalities and its origins. Mechanics laws may be applied to bone parts that make up cranium. A strain applied on one of those parts will drive determined effect on the others. All these lacks of balance and strains set hallmarks on the cranium that biodynamics may study. These phenomena of craniofacial disharmonies are well known in other fields of medicine such as Orthodontics, Dentofacial Orthopedics and Osteopathy. Their approach consists in understanding how cranium and face of children and adults affected have evolved. Traditional ways of analysis are not enough to understand observed abnormalities. One has to use new tools, such as teleXrays, following Orthodontists. Main axis of our study is structured around craniofacial set architectural biodynamics thinking and its connections with occlusion. It brings together comprehensive anthropological study and sex and age related parameters determination. Craniofacial biodynamics analysis consists in analysing crania parts according to pre-established forms procedures. All crania followed clinical analysis concepts continuously tested in Dentofacial Orthopedics. First this one deals with eventual dental or dentoskeletal perturbation knock-on effect on cranium base. Secondly it makes it possible to analyse opposite phenomena, to say craniofacial perturbations that have an impact on occlusion during the growth. Architectural analysis is based exclusively on teleXrays snapshots taking. This method consists in drawing a number of lines and angles on the snapshot that give values about cranium and face structure and about its modifications during the growth, under the influence of some abnormalities. Anthropological study : We first notice that this population is mainly made up of females. When we consider the graph of the mortality, we see that children mortality is not very high but higher anyway than the one of adolescents. Female mortality among young adults is considerable and could be possibly related to environmental conditions. Maximum male mortality is reached among adults, female one is reached among elderly adults. The crania of this population have a very large width with regard to its length giving a short antero-posterior shape. Following, the horizontal cranium index shows that the people of this population are mainly brachycephals. Index study indicates that brachycephals are logically associated to on the one hand orthocephal and hypsicephal on the other hand tapinocephal. Often cranium height with regard to its length is high but low with regard to its width. Mainly foreheads are domed, large occipital curvature prevails among males while among females large and light curvature is equally present. Foreheads are divergents and wides, often foramen magnum is wide. Architectural analysis : The use of teleradiography allowed us to detect maxillo- mandibular imbalances. Architectural analysis shows that class III (flexion) prevails, for almost half of individuals, over class II (extension). Disharmonies are present at all ages. Class III (flexion) prevails among adults whatever the age, as well as it prevails among males and among females. Class II (extension) rate is about the same among males and among females. Those primitive disharmonies may be ordered in 4 categories, according to spheno-occipital kinetics : Category 1 : sphenoid in anterior rotation, occipital with forward basion Category 2 : sphenoid in anterior rotation, occipital with backward basion Category 3 : sphenoid in posterior rotation, occipital with forward basion Category 4 : sphenoid in posterior rotation, occipital with backward basion Usual kinetics of class II and class III put it respectively in category 4 and 1. Spheno-occipital kinetics following those usual kinetics are said concordant while otherwise they are said discordant. Category 2 prevails strongly among this population. Few category 3 and 4 are observed. Then mainly the people of this population show anterior sphenoid’s kinetics with weak craniofacial contraction. These results emphasize that for most of the people studied here, sphenoid and occipital are no more following the usual dynamics. People with spheno-occipital discordance prevails very strongly. It is important to notice that class II is almost exclusively present in discordance. Other kinds of discordance are observed, not only spheno-occipital but also temporal and occipito-temporal. We noticed multiple discordances too. There is also another noticeable fact, which is the frequent conflict between the occipital bone and the basion part of the basi- occipital. As the basi-occipital goes up, the occipital bone goes down forward insufficiently. This takes place more frequently for class II. The distribution of cranium’s shapes (from horizontal cranium index) as well in class III than in class II, does not show any relation between class and cranium’s shape in this population. Proportions of cranium’s shapes in both classes are similar. Then brachycephal individuals of the population from La Queue-en-Brie end up as well in class II than in class III. Biodynamics analysis : From biodynamics analysis, we must emphasize the important frequency of craniofacial disharmonies in the population of La Queue-en-Brie. Observed craniofacial disharmonies are remarkable not only on quantitative side but also on qualitative side. We found craniostenosis cases, side bending rotation, torsion, craniofacial scoliosis, asymmetries, and dismorphosis. Its etiologies appear heterogeneous. We encountered almost all types of craniostenosis : scaphocephaly, brachycephaly, plagiocephaly and trigonocephaly. Some craniostenosis are responsible for architectural asymmetry of the base of the cranium and also of the face. We noted numerous cases of pseudo-plagiocephaly, which corresponds to a disharmony with the appearance of a plagiocephaly but without coronal sutures perturbation. The origin of it can be varied. The observed asymmetries are present either at one level only either at all levels. Most frequents are at the same time at the level of the vault and at the level of the base. We notice that among individuals affected by an asymmetry, most of the time, right side moves forward more than the left side. As for the mandible, craniofacial asymmetry when present has caused a height’s difference between its ramus. We most often found left side ramus shorter than the right one, in relation with the movement of the temporal. We observed in some individuals that in occlusal position the mandible is shifted, often to the left, and that the mandibular condyle on the opposite side does not fit in its temporo-mandibular joint. Such a mandibular asymmetry could cause in some cases a temporo-mandibular joint dysfunction. Dental joint disorders may also be induced by anomalies of the mandible’s implantation on the cranial base. At the vault level, a sutural deviation, sign of a perturbed growth, is frequently noticed, most of the time on the left side sagittal suture and in second on the right side coronal suture. We found tooth decays the prevalence of which at the premolars and molars appears as well on the maxillary than on the mandible. This localization is standard as well for ancient populations than for modern ones. Similarly the ante-mortem teeth loss concerns males and females in comparable proportions and affects mainly molars, on the mandible more than on the maxillary. Third molar agenesia is relatively frequent and is often affecting both maxillary and mandible. Comparison with other Val-de-Marne necropolis : The comparison with other studies about Val-de-Marne necropolis shows that if, similarly to La Queue-en-Brie, brachycephalization is observed for Chevilly-Larue and Créteil sites, it is not the same for Ivry-Parmentier site that exhibits mainly dolichocephals. Although the populations of La Queue-en-Brie and Chevilly-Larue both show brachycephalization, their craniofacial morphogenetic process appears to have taken place differently as the rates obtained for class II and class III come out reversed on both sites. Craniofacial asymmetries are present on all the sites of the comparison. However this is in the population of Chevilly-Larue that we find the higher rate, with predominance of the asymmetries at the vault’s level over the ones at the face’s or base’s level with a ratio about 2/3 of the last compared to the first, while the rates between those asymmetries are close for the other sites, in particular La Queue-en-Brie. As for the rates level of observed asymmetries, La Queue-en-Brie comes into second position after Chevilly-Larue, showing by this one of the important features of our site.