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- Axelson, Hans W, et al.
(författare)
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Trigeminal Nerve Stimulation Does Not Acutely Affect Cortical Excitability in Healthy Subjects
- 2014
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Ingår i: Brain Stimulation. - : Elsevier BV. - 1935-861X .- 1876-4754. ; 7:4, s. 613-617
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Trigeminal nerve stimulation (TNS) has recently emerged as a new therapeutic option for patients with drug-resistant epilepsy but its potential mechanisms of action are not known. Since other antiepileptic treatments have been shown to alter cortical excitability, thereby reducing the liability to seizures, it has been suggested that cranial nerve stimulation such as TNS may act in the same way.OBJECTIVE: To study whether TNS has the potential to alter cortical excitability in healthy subjects.METHODS: An adaptive paired-pulse transcranial magnetic stimulation protocol stimulating the dominant hand motor area was used to measure resting motor threshold (rMT), short-interval intracortical inhibition (SICI), intracortical facilitation (ICF) and long-interval intracortical inhibition (LICI) before, during, and after 40 min of 120 Hz bilateral external continuous trigeminal nerve stimulation. Neuronavigation was used for guidance.RESULTS: TNS was well tolerated by all subjects. No significant changes were seen in the parameters studied.CONCLUSION: Unlike for example anti-epileptic drugs and the ketogenic diet, trigeminal nerve stimulation does not seem to alter cortical excitability in healthy subjects. This is the first study on cortical excitability in relation to continuous trigeminal nerve stimulation. It still remains to be proven that TNS has the prerequisites to effectively counteract epileptic events in humans.
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- Caliandro, Pietro, et al.
(författare)
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Jitter of Corticospinal Neurons During Repetitive Transcranial Magnetic Stimulation : Method and Possible Clinical Implications
- 2014
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Ingår i: Brain Stimulation. - : Elsevier BV. - 1935-861X .- 1876-4754. ; 7:4, s. 580-586
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Tidskriftsartikel (refereegranskat)abstract
- Background: Repetitive transcranial magnetic stimulation (rTMS) of the motor cortex activates corticospinal neurons mainly through the depolarization of cortico-cortical axons belonging to interneurons of superficial layers. Objective: We used single-fiber electromyography (SFEMG) to estimate the "central jitter" of activation latency of interneural pools from one pulse of TMS to another. Methods: We evaluated 10 healthy subjects and one patient with multiple sclerosis. By recording SFEMG evoked activity from the left first dorsal interosseous (FDI), we first used a standard repetitive electrical 3 Hz stimulation of the ulnar nerve at the wrist to calculate the mean consecutive difference from at least 10 different potentials. The same procedure was applied during 3 Hz repetitive TMS of the contralateral motor cortex. The corticospinal monosynaptic connection of the FDI and the selectivity of SFEMG recording physiologically justified the subtraction of the "peripheral jitter" from the whole cortico-muscular jitter, obtaining an estimation of the actual "central jitter." Results: All subjects completed the study. The peripheral jitter was 28 mu s +/- 6 and the cortico-muscular jitter was 344 mu s +/- 97. The estimated central jitter was 343 +/- 97 mu s. In the patient the central jitter was 846 mu s, a value more than twice the central jitter in healthy subjects. Conclusion: Current results demonstrate that the evaluation of the central component of the cumulative cortico-muscular latency variability in healthy subjects is feasible with a minimally invasive approach. We present and discuss this methodology and provide a "proof of concept" of its potential clinical applicability in a patient with multiple sclerosis.
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- Gupta, Vikas, et al.
(författare)
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Automated three-dimensional tracking of the left ventricular myocardium in time-resolved and dose-modulated cardiac CT images using deformable image registration
- 2018
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Ingår i: Journal of Cardiovascular Computed Tomography. - : Elsevier. - 1934-5925. ; 12:2, s. 139-148
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Tidskriftsartikel (refereegranskat)abstract
- Background Assessment of myocardial deformation from time-resolved cardiac computed tomography (4D CT) would augment the already available functional information from such an examination without incurring any additional costs. A deformable image registration (DIR) based approach is proposed to allow fast and automatic myocardial tracking in clinical 4D CT images.Methods Left ventricular myocardial tissue displacement through a cardiac cycle was tracked using a B-spline transformation based DIR. Gradient of such displacements allowed Lagrangian strain estimation with respect to end-diastole in clinical 4D CT data from ten subjects with suspected coronary artery disease. Dice similarity coefficient (DSC), point-to-curve error (PTC), and tracking error were used to assess the tracking accuracy. Wilcoxon signed rank test provided significance of tracking errors. Topology preservation was verified using Jacobian of the deformation. Reliability of estimated strains and torsion (normalized twist angle) was tested in subjects with normal function by comparing them with normal strain in the literature.Results Comparison with manual tracking showed high accuracy (DSC: 0.99± 0.05; PTC: 0.56mm± 0.47 mm) and resulted in determinant(Jacobian) > 0 for all subjects, indicating preservation of topology. Average radial (0.13 mm), angular (0.64) and longitudinal (0.10 mm) tracking errors for the entire cohort were not significant (p > 0.9). For patients with normal function, average strain [circumferential, radial, longitudinal] and peak torsion estimates were: [-23.5%, 31.1%, −17.2%] and 7.22°, respectively. These estimates were in conformity with the reported normal ranges in the existing literature.Conclusions Accurate wall deformation tracking and subsequent strain estimation are feasible with the proposed method using only routine time-resolved 3D cardiac CT.
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- Hansson, Nicolaj C., et al.
(författare)
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The impact of calcium volume and distribution in aortic root injury related to balloon-expandable transcatheter aortic valve replacement
- 2015
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Ingår i: JOURNAL OF CARDIOVASCULAR COMPUTED TOMOGRAPHY. - : ELSEVIER SCIENCE INC. - 1934-5925. ; 9:5, s. 382-392
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Tidskriftsartikel (refereegranskat)abstract
- Background: A detailed assessment of calcium within the aortic root may provide important additional information regarding the risk of aortic root injury during transcatheter heart valve replacement (TAVR). Objective: We sought to delineate the effect of calcium volume and distribution on aortic root injury during TAVR. Methods: Thirty-three patients experiencing aortic root injury during TAVR with a balloon-expandable valve were compared with a control group of 153 consecutive TAVR patients without aortic root injury (as assessed by post-TAVR multidetector CT). Using commercial software to analyze contrast-enhanced pre-TAVR CT scans, caltium volume was determined in 3 regions: (1) the overall left ventricular outflow tract (LVOT), extending 10 mm down from the aortic annulus plane; (2) the upper LVOT, extending 2 mm down from the annulus plane; and (3) the aortic valve region. Results: Calcium volumes in the upper LVOT (median, 29 vs 0 mm(3); P less than .0001) and overall LVOT (median, 74 vs 3 mm(3); P = .0001) were higher in patients who experienced aortic root injury compared with the control group. Calcium in the aortic valve region did not differ between groups. Upper LVOT calcium volume was more predictive of aortic root injury than overall LVOT calcium volume (area under receiver operating curve [AUG]; 0.78; 95% confidence interval, 0.69-0.86 vs AUC, 0.71; 95% confidence interval, 0.62-0.82; P = .010). Upper LVOT calcium below the noncoronary cusp was significantly more predictive of aortic root injury compared to calcium underneath the right coronary cusp or the left coronary cusp (AUC, 0.81 vs 0.68 vs 0.64). Prosthesis oversizing greater than20% (likelihood ratio test, P = .028) and redilatation (likelihood ratio test, P = .015) improved prediction of aortic root injury by upper LVOT calcium volume. Conclusion: Calcification of the LVOT, especially in the upper LVOT, located below the noncoronary cusp and extending from the annular region, is predictive of aortic root injury during TAVR with a balloon-expandable valve. (C) 2015 Society of Cardiovascular Computed Tomography. All rights reserved.
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