Abstract This experiment was to study the feasibility from direct observation of muscle contraction of the lower extremity fromelectrical stimulation threshold of nerve fascicle in identifying the Iα intrafusal afferent fibers during selective posterior rhizotomy (SPR) and to investigate the clinical relationship between the muscle spasm and the electrical stimulation of nerve fascicles. The electrical stimulation threshold of all nerve fascicles in 36 cases during SPR were analysed statistically. The results showed that there was a significant difference between the electrical stimulation threshold of the severed nerve fascicles and intact nerve fascicles no matter the nerve root or each posterior nerve rootlet was examined. It was simple and reliable for surgeons to identify correctly the Iα intrafusal afferent fibers intraoperatively from direct observation of the electrical stimulation threshold of nerve fascicle.
The brain-computer interface (BCI) systems used in practical applications require as few electroencephalogram (EEG) acquisition channels as possible. However, when it is reduced to one channel, it is difficult to remove the electrooculogram (EOG) artifacts. Therefore, this paper proposed an EOG artifact removal algorithm based on wavelet transform and ensemble empirical mode decomposition. Firstly, the single channel EEG signal is subjected to wavelet transform, and the wavelet components which involve EOG artifact are decomposed by ensemble empirical mode decomposition. Then the predefined autocorrelation coefficient threshold is used to automatically select and remove the intrinsic modal functions which mainly composed of EOG components. And finally the ‘clean’ EEG signal is reconstructed. The comparative experiments on the simulation data and the real data show that the algorithm proposed in this paper solves the problem of automatic removal of EOG artifacts in single-channel EEG signals. It can effectively remove the EOG artifacts when causes less EEG distortion and has less algorithm complexity at the same time. It helps to promote the BCI technology out of the laboratory and toward commercial application.
Objective Using cortex convulsions threshold detector and electrical stimulation in rats cortex convulsions threshold model, compare the efficacy and aging of domestic lamotrigine (LTG) and imported LTG. Methods Electrical stimulation convulsions threshold model in rats after stability, 40 rats were randomly divided into A、B、C、D groups,AandBgroup were divided into three different dose groups: domestic LTG low dose (12.5 mg/kg/d), middle dose (25 mg/kg·d), high dose group (37.5 mg/kg·d); imported LTG low doses (12.5 mg/kg·d), middle dose (25 mg/kg·d), high dose group (37.5 mg/kg·d); Carbamazepine middle dose group (72 mg/kg·d); the control group (normal saline 2 ml/time). Recording electrical stimulation in rats cortex convulsions threshold model after administration, compare the differences before and after the administration. Results Three different dose groups of domestic LTG and imported LTG all hadahigher level of electrical stimulation cortex convulsions threshold, and showedadose-response relationship. Onset time of LTG after administration was 1 to 2 hours, peak time was 3 to 4 hours, maintaining time was 8 to 10 hours. Conclusion LTG can improve cortex convulsions threshold in the electrical stimulated rats, there was no significant difference with carbamazepine, and showedadose-response relationship; Repeat dosing for 4 days, both domestic and imported LIG can maintain effective anticonvulsive effect, the efficacy and the aging of two groups of LTG have no significant difference (P＞0.05).
ObjectiveThis paper aimed to summarize the new progress in surgical indications regarding as maximum diameter from evidence-based medical evidence and morphological rupture-risk assessment of abdominal aortic aneurysms (AAA) and its clinical application value.MethodThe rupture-risk and its mechanism of AAA in specific population and morphological characteristics were reviewed.ResultsAsymptomatic patients in specific subgroups may also benefit from AAA repair by lowering the intervention threshold. Besides the maximum diameter of aneurysm, other morphological factors, such as the true geometric shape, the wall thickness, and mural thrombus also had important predictive value for AAA rupture risk.ConclusionRupture-risk assessment based on the actual individual situation of AAA patients can further facilitate the clinical diagnosis and treatment.
The construction of brain functional network based on resting-state functional magnetic resonance imaging (fMRI) is an effective method to reveal the mechanism of human brain operation, but the common brain functional network generally contains a lot of noise, which leads to wrong analysis results. In this paper, the least absolute shrinkage and selection operator (LASSO) model in compressed sensing is used to reconstruct the brain functional network. This model uses the sparsity of L1-norm penalty term to avoid over fitting problem. Then, it is solved by the fast iterative shrinkage-thresholding algorithm (FISTA), which updates the variables through a shrinkage threshold operation in each iteration to converge to the global optimal solution. The experimental results show that compared with other methods, this method can improve the accuracy of noise reduction and reconstruction of brain functional network to more than 98%, effectively suppress the noise, and help to better explore the function of human brain in noisy environment.
To quantitatively evaluate the upper-limb spasticity of stroke patients in recovery stage, the relationship between surface electromyography (sEMG) characteristic indexes from biceps brachii and triceps brachii and the spasticity were explored, which provides the electrophysiological basis for clinical rehabilitation. Ten patients with spasticity after stroke were selected to be estimated by modified Ashworth (MAS) assessment and a passive elbow sinusoidal motion experiment was carried out. At the same time, the sEMG of biceps and triceps were recorded. The results shows that the reflex electromyographic threshold could reflect the physiological mechanism of spasticity and had significant correlation with MAS scale which showed that sEMG could be prosperous for the clinical quantitative evaluation of spasticity of stroke patients.
At present, fatigue state monitoring of upper limb movement generally relies solely on surface electromyographic signal (sEMG) to identify and classify fatigue, resulting in unstable results and certain limitations. This paper introduces the sEMG signal recognition and motion capture technology into the fatigue state monitoring process and proposes a fatigue analysis method combining an improved EMG fatigue threshold algorithm and biomechanical analysis. In this study, the right upper limb load elbow flexion test was used to simultaneously collect the biceps brachii sEMG signal and upper limb motion capture data, and at the same time the Borg Fatigue Subjective and Self-awareness Scale were used to record the fatigue feelings of the subjects. Then, the fatigue analysis method combining the EMG fatigue threshold algorithm and the biomechanical analysis was combined with four single types: mean power frequency (MPF), spectral moments ratio (SMR), fuzzy approximate entropy (fApEn) and Lempel-Ziv complexity (LZC). The test results of the evaluation index fatigue evaluation method were compared. The test results show that the method in this paper has a recognition rate of 98.6% for the overall fatigue state and 97%, 100%, and 99% for the three states of ease, transition and fatigue, which are more advantageous than other methods. The research results of this paper prove that the method in this paper can effectively prevent secondary injury caused by overtraining during upper limb exercises, and is of great significance for fatigue monitoring.
This paper discusses the relationship between stimulating pulse width and the threshold of electrically evoked compound action potential (ECAP). Firstly, the rheobase and chronaxy from strength-duration curve of nerve fiber was computed using the shepherd's experiment results. Secondly, based on the relationship between ECAP and the action potential of nerve fiber, a mathematical expression to describe the relationship between stimulating pulse width and ECAP threshold was proposed. Thirdly, the parameters were obtained and the feasibility was proved to the expression with the results of experiment using guinea pigs. Research result showed that with ECAP compared to the action potential of nerve fiber, their threshold function relationship with stimulating pulse width was similar, and rheobase from the former was an order smaller in the magnitude than the latter, but the chronaxy was close to each other. These findings may provide meaningful guidance to clinical ECAP measurement and studying speech processing strategies of cochlear implant.
Electric and electronic products are required to pass through the certification on electrical safety performance before entering into the market in order to reduce electrical shock and electrical fire so as to protect the safety of people and property. The leakage current is the most important factor in testing the electrical safety performance and the test theory is based on the perception current effect and threshold. The traditional method testing the current threshold for perception only depends on the sensing of the human body and is affected by psychological factors. Some authors filter the effect of subjective sensation by using physiological and psychological statistical algorithm in recent years and the reliability and consistency of the experiment data are improved. We established an experiment system of testing the human body's current threshold for perception based on EEG feature analysis, and obtained 967 groups of data. We used wavelet packet analysis to detect α wave from EEG, and used FFT to do spectral analysis on α wave before and after the current flew through the human body. The study has shown that about 97.72% α wave energy changes significantly when electrical stimulation occurs. It is well proved that when the EEG feature identification is applied to test the human body current threshold for perception, and meanwhile α wave energy change and human body sensing are used together to confirm if the current flowing through the human body reaches the perception threshold, the measurement of the human body current threshold for perception could be carried out objectively and accurately.
Red blood cell (RBC) transfusions are frequently used in cardiac surgery. A minority of patients assume most of the blood products transfusion during and after cardiac operations. Observational analysis of transfusion in patients undergoing cardiac surgery has uniformly demonstrated that RBC transfusion is associated with a significantly increasing risk of all-cause mortality and other serious adverse outcomes. In addition, it is an established fact that such patients can tolerate relatively low hemoglubin (Hb) levels. Consequently, it becomes widely accepted that appropriate limitation of transfusions could confer a substantial benefit to patients and decrease the use of limited resource. As a result, a restrictive threshold for blood transfusion is likely to be favored under most circumstances. However, an increasing amount of data differing from the observational analysis shows that clinical outcomes in patients who received transfusions with restrictive thresholds for Hb level are not superior to those with liberal thresholds. It has created a new uncertainty regarding the use of a restrictive threshold for transfusion during the perioperative period of cardiac surgery.