Effect of skull thickness and conductivity on current propagation for noninvasively injected currents

2021 ◽  
Author(s):  
Mats Forssell ◽  
Chaitanya Goswami ◽  
Ashwati Krishnan ◽  
Maysam Chamanzar ◽  
Pulkit Grover
Keyword(s):  
Skull Thickness

Technical and radiographic considerations for magnetic resonance imaging–guided focused ultrasound capsulotomy

2020 ◽  
pp. 1-9 ◽  
Author(s):  
Benjamin Davidson ◽  
Karim Mithani ◽  
Yuexi Huang ◽  
Ryan M. Jones ◽  
Maged Goubran ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Focused Ultrasound ◽  
Neurosurgical Procedures ◽  
Lesion Volume ◽  
Angle Of Incidence ◽  
Resonance Imaging ◽  
Radiographic Findings ◽  
Compulsive Disorder ◽  
Skull Thickness

OBJECTIVEMagnetic resonance imaging–guided focused ultrasound (MRgFUS) is an emerging treatment modality that enables incisionless ablative neurosurgical procedures. Bilateral MRgFUS capsulotomy has recently been demonstrated to be safe and effective in treating obsessive-compulsive disorder (OCD) and major depressive disorder (MDD). Preliminary evidence has suggested that bilateral MRgFUS capsulotomy can present increased difficulties in reaching lesional temperatures as compared to unilateral thalamotomy. The authors of this article aimed to study the parameters associated with successful MRgFUS capsulotomy lesioning and to present longitudinal radiographic findings following MRgFUS capsulotomy.METHODSUsing data from 22 attempted MRgFUS capsulotomy treatments, the authors investigated the relationship between various sonication parameters and the maximal temperature achieved at the intracranial target. Lesion volume and morphology were analyzed longitudinally using structural and diffusion tensor imaging. A retreatment procedure was attempted in one patient, and their postoperative imaging is presented.RESULTSSkull density ratio (SDR), skull thickness, and angle of incidence were significantly correlated with the maximal temperature achieved. MRgFUS capsulotomy lesions appeared similar to those following MRgFUS thalamotomy, with three concentric zones observed on MRI. Lesion volumes regressed substantially over time following MRgFUS. Fractional anisotropy analysis revealed a disruption in white matter integrity, followed by a gradual return to near-baseline levels concurrent with lesion regression. In the patient who underwent retreatment, successful bilateral lesioning was achieved, and there were no adverse clinical or radiographic events.CONCLUSIONSWith the current iteration of MRgFUS technology, skull-related parameters such as SDR, skull thickness, and angle of incidence should be considered when selecting patients suitable for MRgFUS capsulotomy. Lesions appear to follow morphological patterns similar to what is seen following MRgFUS thalamotomy. Retreatment appears to be safe, although additional cases will be necessary to further evaluate the associated safety profile.

Cranial asymmetry secondary to unilateral hemispheric damage during late childhood

1980 ◽  
Vol 52 (3) ◽  
pp. 423-425 ◽  
Author(s):  
Allen R. Wyler ◽  
Arthur A. Ward
Keyword(s):  
Late Childhood ◽  
Content Type ◽  
Cortical Damage ◽  
Cranial Asymmetry ◽  
Skull Thickness ◽  
Fine Print

✓ Skull abnormalities such as unilateral hypertrophy of skull thickness, enlarged sinuses, and elevated petrous ridge with contralateral body hemiatrophy are commonly associated with hemispheric damage that occurs during infancy. The present case emphasizes that such changes may be associated with cortical damage during late childhood.

Skull thickness and magnitude of EEG alpha activity

2008 ◽  
Vol 119 (6) ◽  
pp. 1271-1280 ◽  
Author(s):  
Dirk Hagemann ◽  
Johannes Hewig ◽  
Christof Walter ◽  
Ewald Naumann
Keyword(s):  
Alpha Activity ◽  
Eeg Alpha ◽  
Eeg Alpha Activity ◽  
Skull Thickness

Skull thickness in patients with skeletal deep bite

2008 ◽  
Vol 11 (2) ◽  
pp. 119-123 ◽  
Author(s):  
PE Jacobsen ◽  
I Kjær ◽  
L Sonnesen
Keyword(s):  
Deep Bite ◽  
Skull Thickness

scholarly journals Skull bone thickness versus malocclusion

2015 ◽  
Vol 5 ◽  
pp. 255-261
Author(s):  
D. K. Mahamad Iqbal ◽  
Vivek B. Amin ◽  
Rohan Mascarenhas ◽  
Akther Husain
Keyword(s):  
Class Ii ◽  
Parietal Bone ◽  
Frontal Bone ◽  
Class I ◽  
Class Ii Malocclusion ◽  
Class Iii ◽  
Class Iii Malocclusion ◽  
Bone Thickness ◽  
Significant Difference ◽  
Skull Thickness

Objective The objectives of this study were to determine the thickness of skull bones, namely frontal, parietal, and occipital bones in Class I, Class II, and Class III patients. Materials and Methods Three hundred subjects who reported to the Department of Orthodontics requiring orthodontic treatment within the age group 17-35 were selected for the study. They were subdivided into three groups of 100 each according to the skeletal and dental relation. Profile radiographs were taken and the tracings were then scanned, and uploaded to the MATLAB 7.6.0 (R 2008a) software. The total surface areas of the individual bones were estimated by the software, which represented the thickness of each bone. Result Frontal bone was the thickest in Class III malocclusion group and the thinnest in Class II malocclusion group. But the parietal and occipital bone thickness were not significant. During gender differentiation in Class I, malocclusion group frontal bone thickness was more in males than females, In Class II, malocclusion parietal bone thickness was more in males than females. No statistically significant difference exists between genders, in Class III malocclusion group. During inter-comparison, the frontal bone thickness was significant when compared with Class I and Class II malocclusion groups and Class II and Class III malocclusion groups. Conclusion The differences in skull thickness in various malocclusions can be used as an adjunct in diagnosis and treatment planning for orthodontic patients. It was found that the new method (MATLAB 7.6.0 [R 2008a] software) of measuring skull thickness was easier, faster, precise, and accurate.

scholarly journals Association of AHI and Other Patient Factors with Calvarial Thickness

2018 ◽  
Vol 1 (1) ◽  
Author(s):  
Amit Nag, BS ◽  
Cyrus Rabbani, MD ◽  
Mohamad Z. Saltagi, MD ◽  
Elizabeth Schueth, BS ◽  
Rick F. Nelson, MD, PhD
Keyword(s):  
Mixed Model ◽  
Female Gender ◽  
Bone Age ◽  
Bone Thickness ◽  
3D Slicer ◽  
Mixed Model Analysis ◽  
Sleep Studies ◽  
Number Of Factors ◽  
Obstructive Sleep ◽  
Skull Thickness

Background and Hypothesis: Temporal spontaneous cerebrospinal fluid (sCSF) leaks occur when spinal fluid leaks through defects in the skull base bone. Patients with sCSF leaks have approximately 22% thinner skulls but no change in extracranial bone thickness, suggesting an intracranial process causes skull thinning and the development of sCSF leaks.  Approximately 83% of sCSF leak patients have obstructive sleep apnea (OSA) as measured by the apnea-hyponea index (AHI) and OSA is associated with spikes in intracranial pressure. We hypothesize that AHI is associated with isolated skull thinning in the general population.  Experimental Design:  High resolution head CT images from patients with diagnostic sleep studies at IU health from 2010 to 2017 were analyzed (IRB approved) using 3D slicer to measure skull thickness of the squamous temporal bone. Age, body mass index (BMI), race and diabetes recorded. Mixed model analysis was used to determine the effect of a number of factors on skull thickness.  Results: 344 CT scans were analyzed. Increased AHI was significantly associated with thinning of the calvarium [2.68 mm - 0.003x, (x = AHI point)  P<0.02], while thickening of the calvarium was associated with age [CI = 0.005 to 0.011 per year, P<0.001] and BMI [CI = 0.003 to 0.015 per mg/kg2, P<0.003]. Female gender (P=0.016) and diabetes (P=0.005) were linked to thickening of the calvarium. Hypertension had no effect on calvarial and zygoma thickness (P=0.244 and 0.575, respectively). The extracranial zygoma thickness was not associated with AHI (P=0.54) or BMI (P=0.811) but the zygoma thinned significantly with age [CI = -0.01 to - 0.002, P<0.002] and female gender (P<0.001).  Conclusion and Potential Impact:  OSA is associated with skull thinning and may play a pathologic role in the development of sCSF leaks over time. 

Inadequate Acoustical Temporal Bone Window in Patients with a Transient Ischemic Attack or Minor Stroke: Role of Skull Thickness and Bone Density

2008 ◽  
Vol 34 (6) ◽  
pp. 923-929 ◽  
Author(s):  
Annemarie D. Wijnhoud ◽  
Martine Franckena ◽  
Aad van der Lugt ◽  
Peter J. Koudstaal ◽  
en Diederik W.J. Dippel
Keyword(s):  
Bone Density ◽  
Temporal Bone ◽  
Transient Ischemic Attack ◽  
Minor Stroke ◽  
Bone Window ◽  
Ischemic Attack ◽  
Skull Thickness

scholarly journals Evaluation of a spring-powered captive bolt gun for killing kangaroo pouch young

2014 ◽  
Vol 41 (7) ◽  
pp. 623 ◽  
Author(s):  
T. M. Sharp ◽  
S. R. McLeod ◽  
K. E. A. Leggett ◽  
T. J. Gibson
Keyword(s):  
Current Method ◽  
Domestic Animal ◽  
The Public ◽  
Blunt Head Trauma ◽  
Captive Bolt Gun ◽  
Base Of The Skull ◽  
Bolt Diameter ◽  
The Brain ◽  
Skull Thickness ◽  
Commercial Harvesting

Context During commercial harvesting or non-commercial kangaroo culling programs, dependent young of shot females are required to be euthanased to prevent suffering and because they would be unlikely to survive. However, the current method for killing pouch young, namely a single, forceful blow to the base of the skull, is applied inconsistently by operators and perceived by the public to be inhumane. Aims To determine whether an alternative method for killing pouch young, namely a spring-operated captive bolt gun, is effective at causing insensibility in kangaroo pouch young. Methods Trials of spring-operated captive bolt guns were conducted first on the heads of 15 dead kangaroo young and then on 21 live pouch young during commercial harvesting. We assessed the effectiveness at causing insensibility in live animals and damage caused to specific brain areas. We also measured depth of bolt penetration and skull thickness. Performance characteristics (e.g. bolt velocity) of two types of spring-operated guns were also measured and compared with cartridge-powered devices. Key results When tested on the heads of dead animals, the spring-operated captive bolt gun consistently produced a large entrance cavity and a well defined wound tract, which extended into the cerebrum, almost extending the full thickness of the brain, including the brainstem. When tested on live pouch young, the captive bolt gun caused immediate insensibility in only 13 of 21 animals. This 62% success rate is significantly below the 95% minimum acceptable threshold for captive bolt devices in domestic animal abattoirs. Failure to stun was related to bolt placement, but other factors such as bolt velocity, bolt diameter and skull properties such as thickness and hardness might have also contributed. Spring-operated captive bolt guns delivered 20 times less kinetic energy than did cartridge-powered devices. Conclusions Spring-operated captive bolt guns cannot be recommended as an acceptable or humane method for stunning or killing kangaroo pouch young. Implications Captive bolt guns have potential as a practical alternative to blunt head trauma for effective euthanasia and reducing animal (and observer) distress. However, operators must continue to use the existing prescribed killing methods until cartridge-powered captive bolt guns have been trialled as an alternative bolt propelling method.

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