Double Transverse Foramina-An Anatomical Basis for Possible Vertebrobasilar Insufficiency Risk and Vertebral Artery Injury.

Cervical vertebrae may exhibit the anomalous presence of a double transverse foramen (DTF) that may impact the anatomy of related structures that traverse the cervical region, such as the vertebral artery (VA). This retrospective anatomical study utilized CT angiography cervical scans to examine the prevalence of DTF, VA, and TF areas. The subjects were separated into two groups: normal TF (NTF group; 26 males and 21 females) and double TF (DTF group; 21 males and 24 females). The males presented significantly higher TF area values (30.31 ± 4.52 mm2) than the females (27.48 ± 1.69 mm2) in the NTF group (p = 0.006). The sex differences disappeared when a DTF was present (p = 0.662). There were no differences in the VA area values between the sexes in both the NTF and DTF groups (p = 0.184). No significant differences in the VA area values between males of the NTF and DTF groups (p = 0.485) were noted. The DTF subjects presented an increased VA/TF area ratio than the NTF subjects (p < 0.001). This study showed that DTF presence reduced the TF area. In contrast, the VA area did not change despite the decreasing TF area. This might be an anatomical risk for transient vertebrobasilar insufficiency in subjects with DTF, especially in females, because VA space in the TF is less in DTF subjects than in NTF subjects. This may lead to easy VA compression in DTF subjects following neck trauma.

Assessing thoraco-pelvic covariation in Homo sapiens and Pan troglodytes: A 3D geometric morphometric approach.

OBJECTIVES: Understanding thoraco-pelvic integration in Homo sapiens and their closest living relatives (genus Pan) is of great importance within the context of human body shape evolution. However, studies assessing thoraco-pelvic covariation across Hominoidea species are scarce, although recent research would suggest shared covariation patterns in humans and chimpanzees but also species-specific features, with sexual dimorphism and allometry influencing thoraco-pelvic covariation in these taxa differently. MATERIAL AND METHODS: N = 30 adult H. sapiens and N = 10 adult Pan troglodytes torso 3D models were analyzed using 3D geometric morphometrics and linear measurements. Effects of sexual dimorphism and allometry on thoraco-pelvic covariation were assessed via regression analyses, and patterns of thoraco-pelvic covariation in humans and chimpanzees were computed via Two-Block Partial Least Squares analyses. RESULTS: Results confirm the existence of common aspects of thoraco-pelvic covariation in humans and chimpanzees, and also species-specific covariation in H. sapiens that is strongly influenced by sexual dimorphism and allometry. Species-specific covariation patterns in chimpanzees could not be confirmed because of the small sample size, but metrics point to a correspondence between the most caudal ribs and iliac crest morphology that would be irrespective of sex. CONCLUSIONS: This study suggests that humans and chimpanzees share common aspects of thoraco-pelvic covariation but might differ in others. In humans, torso integration is strongly influenced by sexual dimorphism and allometry, whilst in chimpanzees it may not be. This study also highlights the importance not only of torso widths but also of torso depths when describing patterns of thoraco-pelvic covariation in primates. Larger samples are necessary to support these interpretations.

Krapina atlases suggest a high prevalence of anatomical variations in the first cervical vertebra of Neanderthals.

The first cervical vertebra, atlas, and its anatomical variants have been widely studied in Homo sapiens. However, in Neanderthals, the presence of anatomical variants of the atlas has been very little studied until very recently. Only the Neanderthal group from the El Sidrón site (Spain) has been analysed with regard to the anatomical variants of the atlas. A high prevalence of anatomical variants has been described in this sample, which points to low genetic diversity in this Neanderthal group. Even so, the high prevalence of anatomical variations detected in El Sidrón Neanderthal atlases needs to be confirmed by analysing more Neanderthal remains. In this context, we analysed the possible presence of anatomical variants in the three Neanderthal atlases recovered from the Krapina site (Croatia) within the Neanderthal lineage. Two of the three Krapina atlases presented anatomical variations. One atlas (Krapina 98) had an unclosed transverse foramen and the other (Krapina 99) presented a non-fused anterior atlas arch. Moreover, an extended review of the bibliography also showed these anatomical variations in other Middle and Upper Pleistocene hominins, leading us to hypothesise that anatomical variations of the atlas had a higher prevalence in extinct hominins than in modern humans.

Association between ribs shape and pulmonary function in patients with Osteogenesis Imperfecta.

The aim of the present study was to test the hypothesis that ribs shape changes in patients with OI are more relevant for respiratory function than thoracic spine shape. We used 3D geometric morphometrics to quantify rib cage morphology in OI patients and controls, and to investigate its relationship with forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1), expressed as absolute value and as percentage of predicted value (% pred). Regression analyses on the full sample showed a significant relation between rib shape and FEV1, FVC and FVC % pred whereas thoracic spine shape was not related to any parameter. Subsequent regression analyses on OI patients confirmed significant relations between dynamic lung volumes and rib shape changes. Lower FVC and FEV1 values are identified in OI patients that present more horizontally aligned ribs, a greater antero-posterior depth due to extreme transverse curve at rib angles and a strong spine invagination, greater asymmetry, and a vertically short, thoraco-lumbar spine, which is relatively straight in at levels 1-8 and shows a marked kyphosis in the thoraco-lumbar transition. Our research seems to support that ribs shape is more relevant for ventilator mechanics in OI patients than the spine shape.

3D geometric morphometric analysis of variation in the human lumbar spine.

OBJECTIVES: The shape of the human lumbar spine is considered to be a consequence of erect posture. In addition, several other factors such as sexual dimorphism and variation in genetic backgrounds also influence lumbar vertebral morphology. Here we use 3D geometric morphometrics (GM) to analyze the 3D morphology of the lumbar spine in different human populations, exploring those potential causes of variation. MATERIAL AND METHODS: We collected 390 (semi) landmarks from 3D models of the CT scans of lumbar spines of seven males and nine females from a Mediterranean population (Spain, Israel) and seven males and either females from a South African population for geometric morphometric (GM) analysis. We carried out Generalized Procrustes Analysis, Principal Components, and Regression analyses to evaluate shape variation; and complemented these analyses with the Cobb Method. RESULTS: The Mediterranean sample was considerably more lordotic than the South African sample. In both populations, female lumbar spines showed proportionally narrower and more craniocaudally elongated lumbar segments than in males. In addition, the point of maximum curvature in females tended to be located more inferiorly than in males. DISCUSSION: Our results show that sexual dimorphism is an important factor of lumbar spine variation that mainly affects features of lumbar spine robustness (height proportions) and the structure-but not the degree-of its curvature. Differences in lordosis, however, are clearer at the inter-population level. This reflects previous conflicting studies casting doubts on pregnancy as an adaptive factor influencing lordosis. Other factors, for example, shape of the individual lumbar vertebrae and intervertebral discs and their relative proportions within the lumbar spine should be considered when exploring variation in vertebral column morphology.

The torso integration hypothesis revisited in Homo sapiens: Contributions to the understanding of hominin body shape evolution.

OBJECTIVES: Lower thoracic widths and curvatures track upper pelvic widths and iliac blades curvatures in hominins and other primates (torso integration hypothesis). However, recent studies suggest that sexual dimorphism could challenge this assumption in Homo sapiens. We test the torso integration hypothesis in two modern human populations, both considering and excluding the effect of sexual dimorphism. We further assess covariation patterns between different thoracic and pelvic levels, and we explore the allometric effects on torso shape variation. MATERIAL AND METHODS: A sex-balanced sample of 50 anatomically connected torsos (25 Mediterraneans, 25 Sub-Saharan Africans) was segmented from computed tomography scans. We compared the maximum medio-lateral width at seventh-ninth rib levels with pelvic bi-iliac breadth in males and females within both populations. We measured 1,030 (semi)landmarks on 3D torso models, and torso shape variation, mean size and shape comparisons, thoraco-pelvic covariation and allometric effects were quantified through 3D geometric morphometrics. RESULTS: Females show narrow thoraces and wide pelves and males show wide thoraces and narrow pelves, although this trend is more evident in Mediterraneans than in Sub-Saharans. Equal thoracic and pelvic widths, depths and curvatures were found in absence of sexual dimorphism. The highest strength of covariation was found between the lowest rib levels and the ilia, and allometric analyses showed that smaller torsos were wider than larger torsos. CONCLUSIONS: This is the first study testing statistically the torso integration hypothesis in anatomically connected torsos. We propose a new and more complex torso integration model in H. sapiens with sexual dimorphism leading to different thoracic and pelvic widths and curvatures. These findings have important implications in hominin body shape reconstructions.

Can the transverse foramen/vertebral artery ratio of double transverse foramen subjects be a risk for vertebrobasilar transient ischemic attacks?

The C6 is the cervical vertebra into which the vertebral artery enters the passage of the transverse foramen and it is the vertebra most affected by double transverse foramina. There is currently little information about the relation between the vertebral artery and the double transverse foramen in C6. We aimed to test whether subjects with a double transverse foramen in C6 have a reduced transverse foramen/vertebral artery ratio when compared with normal anatomy subjects who possess a single transverse foramen which may be a risk for transient vertebral artery stenosis. We measured the area of the transverse foramen and the vertebral artery in 27 double transverse and 56 normal anatomy subjects using computed tomography angiography. We found significant differences in the area of the transverse foramen between double transverse and normal subjects (P < 0.001) but not between the vertebral artery area of double transverse and normal subjects (P = 0.829). The subjects with double transverse foramina have a reduced transverse foramen/vertebral artery ratio, which may be a possible risk for transient vertebral artery stenosis.

Unexpected Persistent Dentocentral Synchondrosis of C2.

BACKGROUND: The persistence of synchondrosis in adulthood can confound diagnostic decisions made during patient management. CASE DESCRIPTION: A 59-year-old woman who presented neck pain, acute headache, and acute cervical myelopathy symptoms after suffering whiplash grade 3 in a car rear-end impact underwent a conventional radiologic study that revealed no fracture and no anatomic spine variations. The magnetic resonance imaging study revealed no spinal cord intensity signal changes, but it showed a persistent (remnant) dentocentral synchondrosis that was undetected in a previous conventional radiographic evaluation. CONCLUSIONS: The localization and level of the remnant of the dentocentral synchondrosis are extremely important from the clinical viewpoint because of odontoid and C2 fractures. Neurosurgeons should thus be aware of the possible presence of a persistent (remnant) C2 dentocentral synchondrosis in adult subjects in order to avoid misdiagnosis with C2 fracture.

Analysis of the relationship between the double transverse foramen and the possibility of developing clinical symptoms after whiplash.

Currently, there is no information about the possibility of developing clinical symptoms after whiplash in double transverse foramen subjects. Our aim was to test whether subjects with double transverse foramen have an increased risk of presenting with an acute headache, dizziness, vertebral artery dissection, and vomiting after whiplash.We recorded the absence/presence of double transverse foramen, and the absence/presence of neck pain, acute headache, dizziness, vertebral artery dissection, and vomiting in 85 patients who had suffered whiplash injuries in car rear-end impacts in road traffic accidents. We used the odds ratio test to determine whether double transverse foramen subjects are at a higher risk of developing an acute headache, dizziness, and vomiting than non-double transverse foramen subjects.Although double transverse foramen subjects presented with more clinical symptoms after whiplash, the odds ratio test revealed that their risks of developing acute headache (P = 0.30), dizziness (P = 0.09), or vomiting (P = 0.18) were not significantly greater than in the control group.Double transverse foramen subjects are not at a higher risk of presenting acute headache, dizziness, vertebral artery dissection, and vomiting after whiplash. Clin. Anat. 30:761-766, 2017. © 2017Wiley Periodicals, Inc.

Acute headache attributed to whiplash in arcuate foramen and non-arcuate foramen subjects.

PURPOSE: To test the association between arcuate foramen (AF) in the first cervical vertebra with acute headache attributed to whiplash. METHODS: Retrospective study of 128 patients that suffered a whiplash. The presence or absence of AF was recorded after a radiographic study, as well as the presence or absence of acute headache after the whiplash. RESULTS: The frequency of AF was 17.2%. Patients with bilateral AF presented a significant (p = 0.000, Fisher's test) increase in the frequency of acute headache (90.9%) in comparison with the non-AF group (5.7%). The ratio between the presence and absence of acute headache was 166.6 times higher (IC 95% 18.2-1526.22) in subjects with bilateral AF in comparison with non-AF subjects. CONCLUSIONS: The presence of bilateral AF is associated to an increased frequency of acute headache after suffering a whiplash, information of interest for the attention to these patients.