In the CT scan group, the results showed a wider left thoracic cage and pelvic bone in 33 of 48 cases (68.75 %) compared with only 7 (14.5%) on the right side. In 7 cases (14.5%), the wider distance of the thoracic cage and pelvic bone was not on the same side. In only one case, the right and left sides were equal. This means that in 85% of cases, patients had same-side asymmetry (P = 0.0015) (Table 4).
Chirality and asymmetry between the face and body are common in many populations. Early Greek scientists were pioneers in exploring internal anatomic organ arrangement, and they believed in symmetry of all body structures. It took years of cadaver dissections to show asymmetric arrangement of internal organs.6
How does asymmetry develop? Laterality is controlled by many factors, though genetics have proven to play a significant role. During the gastrulation phase of development, left to right and rotating movements of nodal cilia results in chiral movement of motor proteins of the cytoskeleton and bulk transport of extracellular morphogens. Genetic data may be translated through pH and voltage gradients across the midline, which will activate left/right asymmetry in the vertebrate embryo.7
In recent years, molecular geneticists have made significant contributions to the science of asymmetric vertebrate anatomy and have found that asymmetric animals are evolutionary more progressed than their symmetric ancestors.8 In bilaterian animals not only are the viscera positioned in an asymmetric manner, but functional left/right asymmetry in brain activity has been proven by psychological testing, magnetic resonance imaging, and lesion analysis.9
Human beings and more developed vertebrates normally show left/right asymmetry of the internal organs in addition to the body and skeleton. Lack of this asymmetric development may produce a variety of malformations and disorders.7,10 Normal asymmetric arrangement of internal organs is called situs solitus. Variation from this normal arrangement is called heterotaxy. Arrangement of organs at random is called situs amigos, and complete reversal or mirror imaged arrangement of organs is called situs inversus.11 These last 2 patterns are associated with complex cardiovascular malformations, the etiology of which could be due to genetic factors of monogenic, polygenic, or multifactorial origination.12
In a long-term study, Swedish researchers found that 50% of immotile ciliary syndrome cases have situs inversus, whereas only 14% of the normal population is left-handed.13 It appears that there is no relation between these 2 anatomic and physiologic variations.
Contrary to popular beliefs, symmetry does not always translate to beauty. Zaidel et al.14 found that asymmetric faces often look beautiful in the eyes of others. Indeed, in their study, they created symmetric left/left and right/right composites of “beautiful” faces and chose the most attractive pair members. They found that very attractive faces can often be functionally asymmetric.14
In our study, we attempted to find out whether there is a relationship between asymmetry of the face and body or same-sided laterality of the face and body. Another objective was to see whether one side was dominant over the other. Our results showed not only a widening of the nasal wall predominantly on the left side but surprisingly a wider left side of face and body structure in the majority of cases. These findings were confirmed by picture transposition and CT measurements of thoracic and pelvic cavities.
Other researchers have also demonstrated left-sided predominance in the human anatomy. In a study of 80 European males, the authors found that measurements of eye socket position in relation to the midline were significantly larger on the left-hand side, meaning a more lateral position of the orbits on that side.1 In another study, maxillofacial CT scans were obtained from 48 orthognathic surgery cases (24 mandibular retrusion and 24 mandibular prognathism) with facial asymmetry.15 In an assessment of chin deviation, subjects in this study showed predominantly left-sided deviation regardless of the group studied.
There are other articles on facial laterality showing varying results. Smith et al.16 measured 2 hemifaces of 45 female and 45 male college students with 2D photographs. They found that females on average had a larger right-sided face in comparison to male subjects, who had a larger left side. The most recent article on this subject was published by Ercan et al.17 in 2008. They performed precise measurements of 42 facial landmarks (10 midline, 16 right side, 16 left side) on 2D photographs of 321 young college students (150 males and 171 females). They compared multiple distances on both halves of the face and found that the left side of the face was more dominant in both males and females. They also found that the middle third of the face (maxillary bone, zygomatic corner, and lower orbital border) was the most asymmetric part of the face in both sexes.
Similarly, Haraguchi et al. measured facial dimensions at different ages (651 males and 1149 females; mean age of 15 y; range of 4 to 59 y).18 Asymmetric subjects had 80% wider right-sided hemiface, and 79.3% of those with chin deviation had left-sided laterality. In this regard, during pubertal growth, the proportion of subjects with wider right hemiface decreased (P < 0.0001), whereas the proportion of those with a wider left hemiface increased (P < 0.01). Confirming the above findings, Farkas et al.19 also found larger right-sided faces at childhood ages.
Another set of researchers performed cephalometric analysis on 92 volunteers with right/left asymmetry consisting of 8 linear distance, 9 angular, and 3 mid-facial measurements.20 The result indicated that asymmetry was characterized by a wider left side of the face and a shorter vertical dimension on the right side.
In our study, we believe that asymmetry of the face and the body is a rule, not an exception. Correlation of this asymmetry between the body and face along with left-sided predominance has become noticeable to our authors gradually over the past several decades. Every surgeon, particularly those who are interested in rhinoplasty, should be aware that the right side wall of the nose is narrower than the left, so he/she should be prepared for augmentation or less reduction on the right side versus the left. The significance of these findings serves to enhance existing insight both to patients and surgeons. The patient who is aware of the differential anatomy of his/her body and face will hopefully have a more realistic view about the capabilities of his/her surgeon to produce symmetry and will be less surprised by the outcome of the operation. Our insights can also help surgeons develop a clearer surgical plan to reach a more pleasing and predictable result.
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Copyright © 2017 The Authors. Published by Wolters Kluwer Health, Inc. on behalf of The American Society of Plastic Surgeons.
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