Symmetry of the Human Head—Are Symmetrical Models More Applicable in Numerical Analysis?

Ratajczak, Monika; Ptak, Mariusz; Kwiatkowski, A.; Kubicki, Konrad; Fernandes, Fábio A. O.; Wilhelm, Johannes; Dymek, Mateusz; Sawicki, Marek; Żółkiewski, S.

doi:10.3390/sym13071252

Cited by 6 publications

(3 citation statements)

References 57 publications

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“…the one proximate to the cathode) with a symmetricity ratio of 0.933 and 0.854 (considering mean and max values respectively). It is known that the human head is not perfectly symmetric with reported asymmetries (minor) in the skull and brain anatomies [32]. Given, our model geometry is directly derived from medical images, the asymmetricity in current ow pattern due to a symmetric montage is therefore, not unexpected.…”

Section: Resultsmentioning

confidence: 96%

Unpacking Galvanic Vestibular Stimulation using simulations and relating current flow to reported motions: Comparison across common and specialized electrode placements

Truong,

Thomas,

Ira

et al. 2023

Preprint

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Galvanic Vestibular Stimulation is a non-invasive electrical stimulation technique that is typically used to probe the vestibular system. While commonly delivered using two electrodes, additional electrode placements have been employed. Our objective was to systematically evaluate all known placements, compare induced current flow, and how it relates to the archetypal virtual and sway motions. The ultimate goal is to help users in having a better understanding of the effects of different configurations. We simulated seven placements using an ultra-high-resolution model. Induced electric field (EF) patterns at the cortical and the location of vestibular organs were determined. As expected, current flow patterns are electrode placement specific. Placements with two electrodes generally result in higher EF magnitude. Placements with four electrodes result in lower percentage of current entering the cranial cavity. Symmetric placements do not result in similar EF values in the left and the right organs highlighting inherent anatomical asymmetry. Asymmetric placements may result in as much as ~ 3-fold higher EF in one organ over the other. The percentage of current entering the cranial cavity varies between ~ 15–40% depending on the placement. Detailed analysis such as this may be used to help understand mechanism of action, guide stimulation strategy, ultimately resulting in quantitatively informed rational / optimal choices.

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Section: Resultsmentioning

confidence: 96%

Unpacking Galvanic Vestibular Stimulation using simulations and relating current flow to reported motions: Comparison across common and specialized electrode placements

Truong,

Thomas,

Ira

et al. 2023

Preprint

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“…The energy transfer from the electronic object to the human head follows the one-sided symmetry in the skull. The facial, brain, and skull symmetries are well explained by Ratajczak et al [6].…”

Section: Introductionmentioning

confidence: 80%

Artificial Neural Network Solution for a Fractional-Order Human Skull Model Using a Hybrid Cuckoo Search Algorithm

Waseem,

Ali,

Khattak

et al. 2023

Symmetry

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In this study, a new fractional-order model for human skull heat conduction is tackled by using a neural network, and the results were further modified by using the hybrid cuckoo search algorithm. In order to understand the temperature distribution, we introduced memory effects into our model by using fractional time derivatives. The objective function was constructed in such a way that the L2−error remained at a minimum. The fractional order equation was then calculated by using the proposed biogeography-based hybrid cuckoo search (BHCS) algorithm to approximate the solution. When compared to earlier simulations based on integer-order models, this method enabled us to examine the fractional-order (FO) cases, as well as the integer order. The results are presented in the form of figures and tables for the different case studies. The results obtained for the various parameters were validated numerically against the available literature, where our proposed methodology showed better performance when compared to the least squares method (LSM).

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“…The patient was a 23-year-old Hispanic male, with a height of 174 cm, without previous shoulder pathologies. We assume symmetry of the biomechanical conditions; thus, only one shoulder is studied [25]. DICOM files were used for obtaining the 3D model of bones using the imaging segmentation software 3D Slicer v4.11 [26], applying semi-automatic segmentation.…”

Section: D Modelmentioning

confidence: 99%

Image-Based Numerical Analysis for Isolated Type II SLAP Lesions in Shoulder Abduction and External Rotation

Maldonado,

Puentes,

Quintero

et al. 2023

Diagnostics

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The glenohumeral joint (GHJ) is one of the most critical structures in the shoulder complex. Lesions of the superior labral anterior to posterior (SLAP) cause instability at the joint. Isolated Type II of this lesion is the most common, and its treatment is still under debate. Therefore, this study aimed to determine the biomechanical behavior of soft tissues on the anterior bands of the glenohumeral joint with an Isolated Type II SLAP lesion. Segmentation tools were used to build a 3D model of the shoulder joint from CT-scan and MRI images. The healthy model was studied using finite element analysis. Validation was conducted with a numerical model using ANOVA, and no significant differences were shown (p = 0.47). Then, an Isolated Type II SLAP lesion was produced in the model, and the joint was subjected to 30 degrees of external rotation. A comparison was made for maximum principal strains in the healthy and the injured models. Results revealed that the strain distribution of the anterior bands of the synovial capsule is similar between a healthy and an injured shoulder (p = 0.17). These results demonstrated that GHJ does not significantly deform for an Isolated Type II SLAP lesion subjected to 30-degree external rotation in abduction.

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Symmetry of the Human Head—Are Symmetrical Models More Applicable in Numerical Analysis?

Cited by 6 publications

References 57 publications

Unpacking Galvanic Vestibular Stimulation using simulations and relating current flow to reported motions: Comparison across common and specialized electrode placements

Unpacking Galvanic Vestibular Stimulation using simulations and relating current flow to reported motions: Comparison across common and specialized electrode placements

Artificial Neural Network Solution for a Fractional-Order Human Skull Model Using a Hybrid Cuckoo Search Algorithm

Image-Based Numerical Analysis for Isolated Type II SLAP Lesions in Shoulder Abduction and External Rotation

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