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1.
J Clin Neurophysiol ; 37(1): 56-61, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31335562

RESUMO

PURPOSE: Advances in surface electromyography (sEMG) monitoring allow for long-term data collection in a natural environment, giving objective information that may identify risk of sudden unexpected death in epilepsy and guide clinical decision-making. Generalized tonic-clonic seizure semiology, namely motor tonic and clonic phase duration, may be an important factor in determining the level of seizure control and risk of sudden unexpected death in epilepsy. This study demonstrates a quantitative analysis of sEMG collected with a dedicated wearable device. METHODS: During routine monitoring, 23 generalized tonic-clonic seizures from 19 subjects were simultaneously recorded with video-EEG and sEMG. A continuous wavelet-transform was used to determine the frequency components of sEMG recorded during generalized tonic-clonic seizures. An automated process, incorporating a variant of cross-validation, was created to identify ideal frequencies and magnitude ranges for tonic and clonic phases and determine phase durations. Phase durations determined using sEMG analysis were compared with phase durations determined by independent epileptologists' review of video-EEG. RESULTS: Cross-validation revealed that the optimal frequency bands for tonic and clonic phases are 150 to 270 Hz and 12 to 70 Hz, respectively. The average difference in phase duration calculated using the two methods for tonic and clonic phases and total seizure duration were -0.42 ± 4.94, -5.12 ± 9.68, and -5.11 ± 11.33 seconds, respectively (results presented are TsEMG - TvEEG, µ ± σ). CONCLUSIONS: The automated processing of sEMG presented here accurately identified durations of tonic, clonic, and total motor durations of generalized tonic-clonic seizures similar to durations identified by epileptologists' review of video-EEG.

2.
Epilepsia ; 58(11): 1861-1869, 2017 11.
Artigo em Inglês | MEDLINE | ID: mdl-28980702

RESUMO

OBJECTIVE: A prospective multicenter phase III trial was undertaken to evaluate the performance and tolerability in the epilepsy monitoring unit (EMU) of an investigational wearable surface electromyographic (sEMG) monitoring system for the detection of generalized tonic-clonic seizures (GTCSs). METHODS: One hundred ninety-nine patients with a history of GTCSs who were admitted to the EMU in 11 level IV epilepsy centers for clinically indicated video-electroencephalographic monitoring also received sEMG monitoring with a wearable device that was worn on the arm over the biceps muscle. All recorded sEMG data were processed at a central site using a previously developed detection algorithm. Detected GTCSs were compared to events verified by a majority of three expert reviewers. RESULTS: For all subjects, the detection algorithm detected 35 of 46 (76%, 95% confidence interval [CI] = 0.61-0.87) of the GTCSs, with a positive predictive value (PPV) of 0.03 and a mean false alarm rate (FAR) of 2.52 per 24 h. For data recorded while the device was placed over the midline of the biceps muscle, the system detected 29 of 29 GTCSs (100%, 95% CI = 0.88-1.00), with a detection delay averaging 7.70 s, a PPV of 6.2%, and a mean FAR of 1.44 per 24 h. Mild to moderate adverse events were reported in 28% (55 of 199) of subjects and led to study withdrawal in 9% (17 of 199). These adverse events consisted mostly of skin irritation caused by the electrode patch that resolved without treatment. No serious adverse events were reported. SIGNIFICANCE: Detection of GTCSs using an sEMG monitoring device on the biceps is feasible. Proper positioning of this device is important for accuracy, and for some patients, minimizing the number of false positives may be challenging.


Assuntos
Eletromiografia/métodos , Epilepsia Tônico-Clônica/diagnóstico , Epilepsia Tônico-Clônica/fisiopatologia , Monitorização Ambulatorial/métodos , Adolescente , Adulto , Idoso , Criança , Pré-Escolar , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Adulto Jovem
3.
NMR Biomed ; 29(7): 961-8, 2016 07.
Artigo em Inglês | MEDLINE | ID: mdl-27192391

RESUMO

Hyperbaric oxygen (HBO) therapy has a number of clinical applications. However, the effects of acute HBO on basal cerebral blood flow (CBF) and neurovascular coupling are not well understood. This study explored the use of arterial spin labeling MRI to evaluate changes in baseline and forepaw stimulus-evoked CBF responses in rats (n = 8) during normobaric air (NB), normobaric oxygen (NBO) (100% O2 ), 3 atm absolute (ATA) hyperbaric air (HB) and 3 ATA HBO conditions. T1 was also measured, and the effects of changes in T1 caused by increasing oxygen on the CBF calculation were investigated. The major findings were as follows: (i) increased inhaled oxygen concentrations led to a reduced respiration rate; (ii) increased dissolved paramagnetic oxygen had significant effects on blood and tissue T1 , which affected the CBF calculation using the arterial spin labeling method; (iii) the differences in blood T1 had a larger effect than the differences in tissue T1 on CBF calculation; (iv) if oxygen-induced changes in blood and tissue T1 were not taken into account, CBF was underestimated by 33% at 3 ATA HBO, 10% at NBO and <5% at HB; (v) with correction, CBF values under HBO, HB and NBO were similar (p > 0.05) and all were higher than CBF under NB by ~40% (p < 0.05), indicating that hypercapnia from the reduced respiration rate masks oxygen-induced vasoconstriction, although blood gas was not measured; and (vi) substantial stimulus-evoked CBF increases were detected under HBO, similar to NB, supporting the notion that activation-induced CBF regulation in the brain does not operate through an oxygen-sensing mechanism. CBF MRI provides valuable insights into the effects of oxygen on basal CBF and neurovascular coupling under hyperbaric conditions. Copyright © 2016 John Wiley & Sons, Ltd.


Assuntos
Velocidade do Fluxo Sanguíneo/fisiologia , Circulação Cerebrovascular/fisiologia , Oxigenação Hiperbárica/métodos , Angiografia por Ressonância Magnética/métodos , Oximetria/métodos , Oxigênio/metabolismo , Animais , Masculino , Oxigênio/sangue , Ratos , Ratos Sprague-Dawley
4.
Neuroimage ; 133: 498-503, 2016 06.
Artigo em Inglês | MEDLINE | ID: mdl-27033683

RESUMO

The brain depends on a continuous supply of oxygen to maintain its structural and functional integrity. This study measured T1 from MRI under normobaric air, normobaric oxygen, hyperbaric air, and hyperbaric oxygen (HBO) conditions as a marker of tissue pO2 since dissolved molecular oxygen acts as an endogenous contrast agent. Brain tissue T1 decreased corresponding to increased pO2 with increasing inhaled oxygen concentrations, and tissue oxygenation was estimated from the T1 changes between different inhaled oxygen levels. Tissue pO2 difference maps between different oxygen conditions showed heterogeneous pO2 changes in the brain. MRI-derived tissue pO2 was markedly lower than the arterial pO2 but was slightly higher than venous pO2. Additionally, for comparison with published extracellular tissue pO2 data obtained using oxygen electrodes and other invasive techniques, a model was used to estimate extracellular and intracellular pO2 from the MRI-derived mean tissue pO2. This required multiple assumptions, and so the effects of the assumptions and parameters used in modeling brain pO2 were evaluated. MRI-derived pO2 values were strongly dependent on assumptions about the extra- and intracellular compartments but were relatively less sensitive to variations in the relaxivity constant of oxygen and contribution from oxygen in the cerebral blood compartment. This approach may prove useful in evaluating tissue oxygenation in disease states such as stroke.


Assuntos
Encéfalo/metabolismo , Oxigenação Hiperbárica/métodos , Interpretação de Imagem Assistida por Computador/métodos , Imagem por Ressonância Magnética/métodos , Oximetria/métodos , Oxigênio/sangue , Animais , Masculino , Imagem Molecular/métodos , Ratos , Ratos Sprague-Dawley , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
5.
Neuroimage ; 119: 382-9, 2015 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-26143203

RESUMO

Hyperbaric oxygen (HBO) therapy is used to treat a number of ailments. Improved understanding of how HBO affects neuronal activity, cerebral blood flow (CBF) and blood-oxygenation-level dependent (BOLD) changes could shed light on the role of oxygen in neurovascular coupling and help guide HBO treatments. The goal of this study was to test two hypotheses: i) activation-induced CBF fMRI response is not dependent on hemoglobin deoxygenation, and ii) activation-induced BOLD fMRI is markedly attenuated under HBO. CBF and BOLD fMRI of forepaw stimulation in anesthetized rats under HBO at 3 atmospheres absolute (ATA) were compared with normobaric air. Robust BOLD and CBF fMRI were detected under HBO. Inflow effects and spin-density changes did not contribute significantly to the BOLD fMRI signal under HBO. Analysis of the T2(⁎)-weighted signal at normobaric air and 1, 2 and 3ATA oxygen in the tissue and the superior sagittal sinus showed a strong dependence on increasing inhaled [O2]. Spontaneous electrophysiological activity and evoked local-field potentials were reduced under HBO. The differences between normobaric air and HBO in basal and evoked electrical activity could not fully account for the strong BOLD responses under HBO. We concluded that activation-induced CBF regulation in the brain does not operate through an oxygen-sensing mechanism and that stimulus-evoked BOLD responses and the venous T2(⁎)-weighted signals still have room to increase under 3ATA HBO. To our knowledge, this is the first fMRI study under HBO, providing insights into the effects of HBO on neural activity, neurovascular coupling, tissue oxygenation, and the BOLD signal.


Assuntos
Mapeamento Encefálico , Encéfalo/irrigação sanguínea , Imagem por Ressonância Magnética , Acoplamento Neurovascular , Oxigênio/metabolismo , Pressão do Ar , Animais , Estimulação Elétrica , Frequência Cardíaca , Hemodinâmica , Hemoglobinas/metabolismo , Masculino , Ratos , Ratos Sprague-Dawley , Taxa Respiratória , Córtex Somatossensorial/irrigação sanguínea , Córtex Somatossensorial/fisiologia , Percepção do Tato/fisiologia
6.
Invest Ophthalmol Vis Sci ; 54(7): 5123-31, 2013 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-23821190

RESUMO

PURPOSE: We tested the hypothesis that retinal blood flow has a postocclusive reactive hyperemia response modulated by occlusion duration and metabolic activity, and that choroidal blood flow does not. METHODS: Anesthetized and paralyzed rats (n = 34) were studied. Retinal and choroidal blood flow was measured by laser speckle imaging and laser Doppler flowmetry, respectively. Blood oxygenation level-dependent functional magnetic resonance imaging (BOLD fMRI) was used to measure changes in relative blood oxygenation of the retinal and choroidal circulations. Transient carotid occlusion was elicited with a hydraulic occluder on the common carotid artery. Several occlusion durations were tested during dark, constant light, and flicker light conditions to modulate metabolic demand. The hyperemia response magnitude was quantified by integrating the area above the blood flow baseline for the 3 minutes after release of the occlusion. RESULTS: Systemic arterial pressure (108.2 ± 1.4 mm Hg) was unaffected by the carotid occlusions, and was similar among animals and conditions. Retinal blood flow had a reactive hyperemia, but choroidal blood flow did not (e.g., 14 ± 2%.sec versus 0.5 ± 4%. sec after 60-second occlusion). The hyperemia magnitude increased as a nonlinear function of occlusion duration and reached a plateau at occlusion durations < 60 second. The hyperemia magnitude was not altered by different lighting conditions at occlusion durations of 15 and 60 seconds. BOLD fMRI results were similar to the laser-based blood flow measurements. CONCLUSIONS: The results indicate that metabolic local control has a negligible role in choroidal blood flow regulation and only partially accounts for the blood flow behavior in the retinal circulation.


Assuntos
Corioide/irrigação sanguínea , Hiperemia/fisiopatologia , Retina/fisiologia , Oclusão da Artéria Retiniana/fisiopatologia , Animais , Artérias Carótidas/fisiologia , Fluxometria por Laser-Doppler , Imagem por Ressonância Magnética , Modelos Animais , Ratos , Ratos Long-Evans , Fluxo Sanguíneo Regional/fisiologia
7.
Am J Physiol Regul Integr Comp Physiol ; 302(3): R331-9, 2012 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-22116509

RESUMO

Sex differences in skeletal muscle regeneration are controversial; comparisons of regenerative events between sexes have not been rigorously defined in severe injury models. We comprehensively quantified inflammation and muscle regeneration between sexes and manipulated sex-specific hormones to determine effects on regeneration. Cardiotoxin injury was induced in intact, castrated and ovariectomized female and male mice; ovariectomized mice were replaced with low- or high-dose 17-ß estradiol (E(2)) or progesterone (P4). Extent of injury was comparable between intact mice, but females were more efficient in removal of necrotic debris, despite similar tissue levels of inflammatory cells and chemokines. Myofiber size during regeneration was equivalent between intact mice and after castration or ovariectomy (OVX) but was decreased (P < 0.001) in ovariectomized mice with high-dose E(2) replacement. Intermuscular adipocytes were absent in uninjured muscle, whereas adipocyte area was increased among regenerated myofibers in all groups. Interestingly, intermuscular fat was greater (P = 0.03) in intact females at day 14 compared with intact males. Furthermore, castration increased (P = 0.01) and OVX decreased adipocyte accumulation. After OVX, E(2), but not P4, replacement decreased (P ≤ 0.03) fat accumulation. In conclusion, sex-dependent differences in regeneration consisted of more efficient removal of necrosis and increased fat deposition in females with similar injury, inflammation, and regenerated myofiber size; high-dose E(2) decreased myofiber size and fat deposition. Adipocyte accumulation in regenerating muscle was influenced by sex-specific hormones. Recovery following muscle injury was different between males and females, and sex-specific hormones contributed to these differences, suggesting that sex-specific treatments could be beneficial after injury.


Assuntos
Hormônios Esteroides Gonadais/fisiologia , Metabolismo dos Lipídeos/fisiologia , Músculo Esquelético/patologia , Músculo Esquelético/fisiopatologia , Regeneração/fisiologia , Caracteres Sexuais , Adipócitos/efeitos dos fármacos , Adipócitos/patologia , Adipócitos/fisiologia , Animais , Cardiotoxinas/efeitos adversos , Estradiol/farmacologia , Feminino , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Modelos Animais , Músculo Esquelético/efeitos dos fármacos , Necrose/induzido quimicamente , Necrose/patologia , Orquiectomia , Ovariectomia , Progesterona/farmacologia
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