Cortical Thickness In Relation Research Articles

The estimation of sex, age, and stature from the distal femoral cortical thickness

The estimation of sex, age, and stature from bones play an important role in identifying parts of bodies or skeletal remains. We aimed to explore femoral cortical thickness in relation to formulating predictive models for age, sex, and stature in a cross-section of the Ankara population using Magnetic Resonance Imaging. The study included left and right knee MRI images taken from individuals without trauma-related fractures, mass lesions, or deformities. The study sample comprised 108 subjects. Using the measurements of the femoral right anterior and posterior cortex and left medial cortex, sex could be determined with a mean 77.8% accuracy. When the relationship between age and male sex only was investigated with the correlation test, a strong relationship was seen between the right medial cortical thickness and age (r: 0.35; p: 0.00). No correlation was found between cortical thickness and age in the female group. All the information obtained about the effects of sex, age, and similar factors on the cross-sectional geometry of the long bones can be obtained indirectly on radiographs referring to any population.

Three-year follow-up of changes of cortical bone thickness after implantation of Endo-Exo-Prosthesis (EEP) for transfemoral amputees

IntroductionTranscutaneous Osseointegrated Prosthetic Systems (TOPS) offer a good alternative for patients who cannot be satisfactorily rehabilitated by conventional suspension sockets. The Endo-Exo-Prothesis (EEP, ESKA Orthopaedic Handels GmbH®, Deutschland) is the most implanted TOPS in Germany. Previous studies have shown that cortical thickness increases after implantation of TOPS. The aim of this study is to determine changes of cortical thickness in relation to the time after implantation of the Endo-Fix-Stem.Patients and methodsAll transfemoral amputees treated by EEP from 2007 to 2013 were operated by the last author of this study. X-ray images of 4 follow-up intervals (postoperative, 3 months, 12 months, 3 years) were analyzed retrospectively. The femoral residuum was divided into 3 sections (proximal, middle, distal) with 2 measuring points in each section: medial and lateral. Cortical thickness was measured at these 6 points and compared at regular intervals using the Friedman test for non-parametric dependent variables.ResultsThirty-seven patients with 40 implants were included. The average age was 52.2 years (30–79 years). 83.7% of the patients were male. No statistical significance could be shown for any of the measuring points of the femoral residual (proximal medial, proximal lateral, middle medial, middle lateral, distal medial, distal lateral) among the mean values of the cortical thickness at the different follow-up times (p > 0.05 for all measuring points). Cortical remodeling processes (> 1 millimeter (mm)) occurred in all implants despite a missing statistical significance. Hypertrophy could be confirmed for 42.5% and atrophy for 37.5%. Twenty percent of the cases showed a parallel occurrence of both entities. Cortical changes greater than 5 mm were only observed at the distal end of the femur.ConclusionEven if our results did not show any significant difference, it can be deduced that the osseointegration process leads to a remodeling of the bone structure, both in terms of increased bone formation and bone resorption. However, it has not yet been conclusively clarified which processes lead to hyper- or atrophy. The force transmission between prosthesis and bone and the facultative bacterial colonization of the stoma are still the main factors which may be responsible for the bone remodeling processes.

Developmental Trajectories of Cortical Thickness in Relation to Schizotypy During Adolescence.

Investigating potential gray matter differences in adolescents presenting higher levels of schizotypy personality traits could bring further insights into the development of schizophrenia spectrum disorders. Research has yet to examine the morphological correlates of schizotypy features during adolescence prospectively, and no information is available on the developmental trajectories from adolescence to adulthood. We employed mixed model regression analysis to investigate developmental trajectories of cortical thickness (CT) in relation to schizotypy dimensions in a cohort of 109 adolescents from the general population for whom MRI-scans were acquired over a 5-year period, culminating in a total of 271 scans. Structural data were processed with FreeSurfer software, statistical analyses were conducted using mixed regression models following a ROI-based approach, and schizotypy was assessed with the Schizotypal Personality Questionnaire (SPQ). Accelerated thinning was observed in the posterior cingulate cortex in relation to high levels of positive schizotypy, whereas high levels of disorganized schizotypy were associated with a similar trajectory pattern in the anterior cingulate cortex. The developmental course of CT in the prefrontal, occipital, and cingulate cortices differed between adolescents expressing higher vs lower levels of negative schizotypy. Participants reporting high scores on all schizotypy dimensions were associated with differential trajectories of CT in posterior cingulate cortex and occipital cortex. Consistently with prospective developmental studies of clinical risk conversion, the negative schizotypy dimension appears to constitute the most informative dimension for psychosis-related psychopathology, as its cerebral correlates in adolescents most closely overlap with results found in clinical high risk for psychosis studies.

Physical exercise associated with vitamin D chronic supplementation reduces kidney injury induced by monosodium glutamate.

The aim was to evaluate the effects of chronic vitamin D (VD) supplementation associated with regular swimming over renal histomorphometric aspects in obese rats. Thirty Wistar male rats (5 days old) were used. Twenty four rats were given subcutaneous injections of monosodium glutamate (MSG; 4 g/kg), and six control rats were given an equimolar saline solution. At 21-days-old, the MSG-treated rats were randomly distributed among sedentary animals (S) and exercised (E, swimming; 3x/week). These groups were subdivided into groups orally supplemented with VD (12 μg/kg; 3x/week) or not supplemented (NS), totaling Five experimental groups (n = 6 rats/group): MSG, MSG-SVD, MSG-ENS, MSG-EVD and control groups. In MSG-obese rats, there was such as a decrease in the diameter of the, glomerular tuft, Bowman's capsule, Bowman's space areas, and renal cortical thickness, compared to the control group. In MSG-SVD, MSG-ENS, and MSG-EVD animals, there was an increase in the cortical thickness in relation to the MSG group. In MSG-ENS and MSG-EVD animals, there was a reduction of tubular degeneration in relation to the MSG group. We conclude that physical exercise associated with Vitamin D supplementation can prevent of renal injury, increasing the thickness of the renal cortex and decrease the tubular degeneration.

Sex-specific relationship of cardiometabolic syndrome with lower cortical thickness.

To investigate whether cardiometabolic factors were associated with age-related differences in cortical thickness in relation to sex. In this cross-sectional study, we enrolled 1,322 cognitively normal elderly (≥65 years old) individuals (774 [58.5%] men, 548 [41.5%] women). We measured cortical thickness using a surface-based analysis. We analyzed the associations of cardiometabolic risk factors with cortical thickness using multivariate linear regression models after adjusting for possible confounders and interactions with age. Among women, hypertension (β = -1.119 to -0.024, p < 0.05) and diabetes mellitus (β = -0.920, p = 0.03) were independently associated with lower mean cortical thickness. In addition, there was an interaction effect between obesity (body mass index [BMI] ≥27.5 kg/m2) and age on cortical thickness in women (β = -0.324 to -0.010, p < 0.05), suggesting that age-related differences in cortical thickness were more prominent in obese women compared to women with normal weight. Moreover, low education level (<6 years) was correlated with lower mean cortical thickness (β = -0.053 to -0.046, p < 0.05). Conversely, among men, only being underweight (BMI ≤18.5 kg/m2, β = -2.656 to -0.073, p < 0.05) was associated with lower cortical thickness. Our findings suggest that cortical thickness is more vulnerable to cardiometabolic risk factors in women than in men. Therefore, sex-specific prevention strategies may be needed to protect against accelerated brain aging.

Functional brain connectivity and cortical thickness in relation to chronic pain in post-911 veterans and service members with mTBI

ABSTRACTObjectives: Investigate the relation of chronic pain interference to functional connectivity (FC) of brain regions and to cortical thickness in post-911 Veterans and Service Members (SMs) who sustained a mild traumatic brain injury (mTBI).Methods: This is an observational study with cross-sectional analyses. A sample of 65 enrollees completing initial evaluation at a single site of the Chronic Effects of Neurotrauma Consortium (CENC) reported pain interference ratings on the TBI QOL. Functional connectivity and cortical thickness were measured.Results: Severity of pain interference was negatively related to FC of the default mode network (DMN), i.e., participants who reported more severe pain interference had less FC between mesial prefrontal cortex and posterior regions of the DMN including posterior cingulate cortex and precuneus. Cortical thickness of specific regions was positively related to severity of pain interference.Conclusion: The more that pain was perceived to interfere with daily life, the less the FC between regions in a network associated with self-referential thought and mind wandering. Although cortical thickness in specific brain regions was positively related to severity of pain interference, follow-up longitudinal data, control group data, and study of individual differences in this cohort will expand this initial report and replicate these findings.

Social Responsiveness Scale (SRS) in Relation to Longitudinal Cortical Thickness Changes in Autism Spectrum Disorder.

The relationship between brain development and clinical heterogeneity in autism (ASD) is unknown. This study examines the Social Responsiveness Scale (SRS) in relation to the longitudinal development of cortical thickness. Participants (N = 91 ASD, N = 56 TDC; 3-39years at first scan) were scanned up to three times over a 7-year period. Mixed-effects models examined cortical thickness in relation to SRS score. ASD participants with higher SRS scores showed regionally increased age-related cortical thinning. Regional thickness differences and reduced age-related cortical thinning were found in predominantly right lateralized regions in ASD with decreasing SRS scores over time. Our findings emphasize the importance of examining clinical phenotypes in brain-based studies of ASD.

SA79. Toxoplasma Gondii Affects Posterior Association Cortex and Related Functions in Healthy, but Not Schizophrenia, Individuals

Abstract Background: The apicomplexan protozoa Toxoplasma gondii (TG) is a successful parasite infecting ~30% of the human population, with some evidence to suggest it is more frequent in individuals with schizophrenia. TG has an affinity for the central nervous system and has been linked to cognitive and behavioral changes in rodents as well as humans. It is believed this mechanism contributes to the presentation of some schizophrenia cases. Given the relative absence of neurobiological studies, the aim of this project was to examine the influence of TG status on cortical thickness and cognitive function in a sample of schizophrenia and healthy individuals both seropositive and negative for the parasite. Methods: Schizophrenia (SCZ) = 77 (5 TG positive) and healthy control volunteers (CON) = 36 (11 TG positive) with clinical, cognitive, imaging, and available blood samples were used for the study. At least a 1-cc aliquot of serum from each subject was used for micro-enzyme-linked immunosorbent assay (ELISA) using a commercially available research kit for quantitative immunoenzymatic determination of anti-TG immunoglogulin G (IgG)-class antibodies. Cognitive and clinical functioning was assessed using a standardized battery. Structural T1-weighted images were processed using the FreeSurfer toolkit. Analyses included analysis of variance models examining differences in cortical thickness and cognition between TG seropositive (+) and negative (−) groups per condition (SCZ and CON); and Pearson correlation models of anti-TG IgG antibody titer values with thickness and behavioral variables within each condition group. Results: No significant differences in cortical thickness or cognition were observed in SCZ(+) vs SCZ(−), as well as CON(+) vs CON(−) groups, with the exception of visuospatial reasoning in CON. When correlating against anti-TG IgG titer values and cognition, significant negative relationships were noted with visuospatial reasoning (r = −.39, P = .02) and verbal memory (r = −.36, P = .03) in CON but none in SCZ. Titer values were significantly correlated with cortical thickness of the superior parietal region in SCZ (RH: r = −.24, P = .03) and at a trend level in CON (LH: r = −.31, P = .06; RH: r = −.30, P = .07). Conclusion: To our knowledge, this is the first study to examine cortical thickness in relation to cognitive function in a sample of SCZ and CON subjects with both seropositive and negative TG status. Results revealed the presence of TG appeared to primarily disrupt posterior association cortex and related functions (e.g., visuospatial reasoning) most prominently in healthy individuals but to a minor extent in schizophrenia patients. Overall, our findings suggest TG appears to exert greater influence over the neurobiology of nonpsychiatric individuals relative to psychosis, although addition research is warranted. Small seropositive sample sizes likely underpowered our ability to detect other effects.

Cortical Implications of Advancing Age and Disease Duration in Parkinson's Disease Patients with Postural Instability and Gait Dysfunction.

Parkinson's Disease patients with predominant gait dysfunction appear to have reduced cortical thickness compared to other motor phenotypes. The extent to which advancing age or disease duration impact the pattern of these distinctions is unclear. We examine if PD patients with predominant signs of postural instability and gait dysfunction are distinguished by distinct patterns of cerebral atrophy, and how these differences are influenced by age and disease duration. The Unified Parkinson's Disease Rating Score (UPDRS) was administered to 196 PD patients (age = 61.4±8.9yrs) in the Off and On dopamine state. All completed a structural T1-weighted brain MRI. We defined 3 motor phenotypes: tremor dominant, akinetic-rigid, and postural instability with gait disorder. General linear modeling quantified cortical thickness in relation to disease duration, and motor improvement after dopaminergic therapy. Cortical thickness and subcortical volumes were compared between the three motor subtypes, after controlling for disease duration and age. We identified 177/196 patients who met criteria for a motor subtype. When corrected for disease duration, postural-instability patients had marked cortical thinning of the bilateral frontal-temporal and posterior cortical regions (cuneus/precuneus). After regressing for age, reduced frontal thickness was evident in patients with gait dysfunction. Widespread cortical thinning was associated with increasing disease duration and reduced motor improvement to dopaminergic therapy. Results emphasize that the profile of motor signs, especially prominent gait manifestations, relate to cortical thinning in distinct regions. Unique patterns of atrophy appear to be driven by advancing pathology related to age and disease duration.

Cortical thickness in relation to clinical symptom onset in preclinical AD.

Mild cognitive impairment (MCI) and Alzheimer's disease (AD) dementia are preceded by a phase of disease, referred to as ‘preclinical AD’, during which cognitively normal individuals have evidence of AD pathology in the absence of clinical impairment. This study examined whether a magnetic resonance imaging (MRI) measure of cortical thickness in brain regions, collectively known as ‘AD vulnerable’ regions, predicted the time to onset of clinical symptoms associated with MCI and whether cortical thickness was similarly predictive of clinical symptom onset within 7 years post baseline versus progression at a later point in time. These analyses included 240 participants from the BIOCARD study, a cohort of longitudinally followed individuals who were cognitively normal at the time of their MRI (mean age = 56 years). Participants have been followed for up to 18 years (M follow-up = 11.8 years) and 50 participants with MRIs at baseline have developed MCI or dementia over time (mean time to clinical symptom onset = 7 years). Cortical thickness in AD vulnerable regions was based on the mean thickness of eight cortical regions. Using Cox regression models, we found that lower mean cortical thickness was associated with an increased risk of progression from normal cognition to clinical symptom onset within 7 years of baseline (p = 0.03), but not with progression > 7 years from baseline (p = 0.30). Lower cortical thickness was also associated with higher levels of phosphorylated tau, measured in cerebrospinal fluid at baseline. These results suggest that cortical thinning in AD vulnerable regions is detectable in cognitively normal individuals several years prior to the onset of clinical symptoms that are a harbinger of a diagnosis of MCI, and that the changes are more likely to be evident in the years proximal to clinical symptom onset, consistent with hypothetical AD biomarker models.

Alterações radiográficas do aparato podotroclear de equinos da Polícia Militar de Minas Gerais sem sinais clínicos de doença do osso navicular

Os objetivos deste experimento foram identificar e associar alterações radiográficas do aparato podotoclear de equinos do Regimento de Cavalaria Alferes Tiradentes da Policia Militar do estado de Minas Gerais sem histórico e sinais clínicos de doença do osso navicular. Foi avaliado um total de 33 equinos, de ambos os sexos, com idade entre 10 e 20 anos. Os dígitos torácicos foram radiografados de forma padronizada nas projeções lateromedial (LM), dorsoproximal palmarodistal 65º (DPPD) e palmaroproximal palmarodistal (SK). A radiopacidade medular aumentada em projeção SK foi a principal alteração radiográfica detectada. Essa alteração foi associada a maior número de invaginações sinovais, a maior espessura de cortical em relação à medular em exposição SK e a maior relação corticomedular em exposição LM (P&lt;0,05). Esses achados indicam uma predisposição da população equina para desenvolver a síndrome do osso navicular, possivelmente associada ao trauma repetitivo promovido pelo constante trabalho em piso duro.

Effects of age and symptomatology on cortical thickness in autism spectrum disorders

Several brain regions show structural and functional abnormalities in individuals with autism spectrum disorders (ASD), but the developmental trajectory of abnormalities in these structures and how they may relate to social and communicative impairments are still unclear. We assessed the effects of age on cortical thickness in individuals with ASD, between the ages of 7 and 39 years in comparison to typically developing controls. Additionally, we examined differences in cortical thickness in relation to symptomatology in the ASD group, and their association with age. Analyses were conducted using a general linear model, controlling for sex. Social and communication scores from the Autism Diagnostic Interview-Revised (ADI-R) were correlated with the thickness of regions implicated in those functions. Controls showed widespread cortical thinning relative to the ASD group. Within regions-of-interest, increased thickness in the rostral anterior cingulate cortex was associated with poorer social scores. Additionally, a significant interaction between age and social impairment was found in the orbitofrontal cortex, with more impaired younger children having decreased thickness in this region. These results suggest that differential neurodevelopmental trajectories are present in individuals with ASD and some differences are associated with diagnostic behaviours.

Poster #46 GREY MATTER DENSITY AND CORTICAL THICKNESS VARY WITH DIFFERENT ORBITOFRONTAL SULCOGYRAL PATTERNS

Both impaired white matter connectivity and alterations in gray matter morphometry have repeatedly been reported in schizophrenia. Neurodevelopmental models propose a close linkage between gray matter alterations and white matter deficits. However, there are no studies investigating alterations in cortical thickness in relation to white matter connectivity changes.This combined diffusion tensor imaging (DTI) – surface based morphometry study examined a potential linkage between disruption in white matter connectivity and alterations in cortical thickness. Cortical thickness was analyzed using the FreeSurfer software package (version 4.0.5, http://surfer.nmr.harvard.edu) in a sample of 19 patients with schizophrenia and 20 healthy controls.Whole brain node-by-node correlational analysis revealed a highly significant association (r = −.8, p < .0001) between disturbed white matter connectivity in the superior temporal cortex and diminished cortical thickness in the posterior part of the cingulate cortex (Brodmann area 23/31).This result indicates a significant linkage between disturbed white matter connectivity and reduced cortical thickness in a relevant node of the default mode network that is held to be of high pathophysiological relevance in schizophrenia. The result moreover provides support for the assumption of a neurodevelopmental pathogenesis of the disorder.

Disrupted white matter connectivity is associated with reduced cortical thickness in the cingulate cortex in schizophrenia

IntroductionBoth impaired white matter connectivity and alterations in gray matter morphometry have repeatedly been reported in schizophrenia. Neurodevelopmental models propose a close linkage between gray matter alterations and white matter deficits. However, there are no studies investigating alterations in cortical thickness in relation to white matter connectivity changes. MethodsThis combined diffusion tensor imaging (DTI) – surface based morphometry study examined a potential linkage between disruption in white matter connectivity and alterations in cortical thickness. Cortical thickness was analyzed using the FreeSurfer software package (version 4.0.5, http://surfer.nmr.harvard.edu) in a sample of 19 patients with schizophrenia and 20 healthy controls. ResultsWhole brain node-by-node correlational analysis revealed a highly significant association (r=−.8, p<.0001) between disturbed white matter connectivity in the superior temporal cortex and diminished cortical thickness in the posterior part of the cingulate cortex (Brodmann area 23/31). ConclusionsThis result indicates a significant linkage between disturbed white matter connectivity and reduced cortical thickness in a relevant node of the default mode network that is held to be of high pathophysiological relevance in schizophrenia. The result moreover provides support for the assumption of a neurodevelopmental pathogenesis of the disorder.

Radiographic study of mandibular angular cortical thickness in relation to the presence and eruption status of mandibular third molar

Background: Mandible is one of the largest and strongest facial bones but there are some areas which are physically weak and fractured easily, i.e., angle and condyle. Recent studies demonstrated the correlation of the risk of mandibular angle fractures to the presence of the mandibular third molars. The aim of the present study was to evaluate the mandibular angular cortical thickness in relation to the presence and eruption status of mandibular third molar to verify if the mandibular third molar represent a risk factor for angle fracture or not. Materials and methods: The angular cortical thickness was measured using tracing elements and panoramic radiograph of 160 Iraqi subjects aged from (20-28) years, they were divided equally into four groups according to the status of mandibular third molar which were: Subjects with agenesis of mandibular third molar, subjects with completely erupted mandibular third molar, subjects with complete bony impacted mandibular third molar and subjects with extracted mandibular third molar. Results: Subjects with agenesis registered the greatest value in the mean angular cortical thickness followed by subjects with extracted, completely erupted and complete bony impacted mandibular third molar respectively. Extraction of mandibular third molar improved the angular cortical thickness and this effect had a strong positive linear correlation with the extraction duration. Conclusion: The measurement of the angular cortical thickness was greatly affected by the presence and eruption status of mandibular third molar, such measurements registered its highest values in subjects with third molar agenesis and its lowest values in subjects with complete bony impacted third molar.

Colocalized Structural and Functional Changes in the Cortex of Patients with Trigeminal Neuropathic Pain

BackgroundRecent data suggests that in chronic pain there are changes in gray matter consistent with decreased brain volume, indicating that the disease process may produce morphological changes in the brains of those affected. However, no study has evaluated cortical thickness in relation to specific functional changes in evoked pain. In this study we sought to investigate structural (gray matter thickness) and functional (blood oxygenation dependent level – BOLD) changes in cortical regions of precisely matched patients with chronic trigeminal neuropathic pain (TNP) affecting the right maxillary (V2) division of the trigeminal nerve. The model has a number of advantages including the evaluation of specific changes that can be mapped to known somatotopic anatomy.Methodology/Principal FindingsCortical regions were chosen based on sensory (Somatosensory cortex (SI and SII), motor (MI) and posterior insula), or emotional (DLPFC, Frontal, Anterior Insula, Cingulate) processing of pain. Both structural and functional (to brush-induced allodynia) scans were obtained and averaged from two different imaging sessions separated by 2–6 months in all patients. Age and gender-matched healthy controls were also scanned twice for cortical thickness measurement. Changes in cortical thickness of TNP patients were frequently colocalized and correlated with functional allodynic activations, and included both cortical thickening and thinning in sensorimotor regions, and predominantly thinning in emotional regions.ConclusionsOverall, such patterns of cortical thickness suggest a dynamic functionally-driven plasticity of the brain. These structural changes, which correlated with the pain duration, age-at-onset, pain intensity and cortical activity, may be specific targets for evaluating therapeutic interventions.

Development of a three‐dimensional finite element model of a human mandible containing endosseous dental implants. II. Variables affecting the predictive behavior of a finite element model of a human mandible

The purpose of this study was to propose a systematic approach to validate a finite element model (FEM) of the human mandible and to investigate the effects of changing the geometry and orthotropic material properties on the FEM predictions. Thirty-eight variables affecting the material properties, boundary conditions, and the geometry of a FEM of a human mandible, including two dental implants, were systematically changed, creating a number of FEMs of the mandible. The effects of the variations were quantified as differences in the principal strain magnitudes modeled by the original FEM (gold standard), prior to the sensitivity analyses, and those generated by the changed FEMs. The material properties that had the biggest impact on the predicted cortical principal strain were the shear moduli (up to 31% in difference from the unchanged state), and the absence of cancellous bone (up to 34%). Alterations to the geometry of the mandibular cross section, such as an increase in corpus dimensions, had the greatest effect on principal strain magnitudes (up to 16%). Changes in the cortical thickness in relation to the width of the corpus section modified strain more than alterations to the corpus depth (14% and 5%, respectively). The relatively small difference (up to 13.5%) between the predicted and measured interimplant distances indicates the accuracy of the FEM. Changes in geometry and orthotropic material properties could induce significant changes in strain patterns. These values must therefore be chosen with care when using finite element techniques for predicting stresses, strains, and displacements.

Incidence and mechanical significance of pneumatization in the long bones of birds

The incidence of pneumatization in avian long bones was studied, by direct observation, in a large sample of species. Only proximal bones (humerus and femur) presented pneumatization in the sample studied. The incidence obtained was related to the variation of the maximum cortical thickness and mechanical properties, such as bending strength and flexural Young's modulus. Cortical thickness, bending strength and flexural Young's modulus were significantly lower in pneumatized bones than in marrow-filled bones. Furthermore, some congruence was found between pneumatization and systematic groups when compared. In this sense, Charadriformes was the only order studied with total absence of long bone pneumatization. Results on cortical thickness appear to be in agreement with modelling predictions previously made and with results obtained on other groups of flying vertebrates. The possible selective advantage of reduction in cortical thickness in relation to flying is suggested.

Incidence and mechanical significance of pneumatization in the long bones of birds

The incidence of pneumatization in avian long bones was studied, by direct observation, in a large sample of species. Only proximal bones (humerus and femur) presented pneumatization in the sample studied. The incidence obtained was related to the variation of the maximum cortical thickness and mechanical properties, such as bending strength and flexural Young's modulus. Cortical thickness, bending strength and flexural Young's modulus were significantly lower in pneumatized bones than in marrow-filled bones. Furthermore, some congruence was found between pneumatization and systematic groups when compared. In this sense, Charadriformes was the only order studied with total absence of long bone pneumatization. Results on cortical thickness appear to be in agreement with modelling predictions previously made and with results obtained on other groups of flying vertebrates. The possible selective advantage of reduction in cortical thickness in relation to flying is suggested.