| 1. |
- Antonsson, Malin, 1986, et al.
(författare)
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Post-surgical effects on language in patients with presumed low-grade glioma
- 2018
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Ingår i: Acta Neurologica Scandinavica. - : Hindawi Limited. - 0001-6314. ; 137:5, s. 469-480
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: Low-grade glioma (LGG) is a slow-growing brain tumour often situated in or near areas involved in language and/or cognitive functions. Thus, language impairments due to tumour growth or surgical resection are obvious risks. We aimed to investigate language outcome following surgery in patients with presumed LGG, using a comprehensive and sensitive language assessment. Materials and methods: Thirty-two consecutive patients with presumed LGG were assessed preoperative, early post-operative, and 3 months post-operative using sensitive tests including lexical retrieval, language comprehension and high-level language. The patients’ preoperative language ability was compared with a reference group, but also with performance at post-operative controls. Further, the association between tumour location and language performance pre-and post-operatively was explored. Results: Before surgery, the patients with presumed LGG performed worse on tests of lexical retrieval when compared to a reference group (BNT: LGG-group median 52, Reference-group median 54, P = .002; Animals: LGG-group mean 21.0, Reference-group mean 25, P = 001; Verbs: LGG-group mean 17.3, Reference-group mean 21.4, P = .001). At early post-operative assessment, we observed a decline in all language tests, whereas at 3 months there was only a decline on a single test of lexical retrieval (Animals: preoperative. median 20, post-op median 14, P = .001). The highest proportion of language impairment was found in the group with a tumour in language-eloquent areas at all time-points. Conclusions: Although many patients with a tumour in the left hemisphere deteriorated in their language function directly after surgery, their prognosis for recovery was good.
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| 2. |
- Antonsson, Malin, 1986, et al.
(författare)
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Pre-operative language ability in patients with presumed low-grade glioma
- 2018
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Ingår i: Journal of Neuro-Oncology. - : Springer Science and Business Media LLC. - 0167-594X .- 1573-7373. ; 137:1, s. 93-102
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Tidskriftsartikel (refereegranskat)abstract
- In patients with low-grade glioma (LGG), language deficits are usually only found and investigated after surgery. Deficits may be present before surgery but to date, studies have yielded varying results regarding the extent of this problem and in what language domains deficits may occur. This study therefore aims to explore the language ability of patients who have recently received a presumptive diagnosis of low-grade glioma, and also to see whether they reported any changes in their language ability before receiving treatment. Twenty-three patients were tested using a comprehensive test battery that consisted of standard aphasia tests and tests of lexical retrieval and high-level language functions. The patients were also asked whether they had noticed any change in their use of language or ability to communicate. The test scores were compared to a matched reference group and to clinical norms. The presumed LGG group performed significantly worse than the reference group on two tests of lexical retrieval. Since five patients after surgery were discovered to have a high-grade glioma, a separate analysis excluding them were performed. These analyses revealed comparable results; however one test of word fluency was no longer significant. Individually, the majority exhibited normal or nearly normal language ability and only a few reported subjective changes in language or ability to communicate. This study shows that patients who have been diagnosed with LGG generally show mild or no language deficits on either objective or subjective assessment.
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| 3. |
- Andreasson, Ann‐Charlotte, et al.
(författare)
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Cortical excitability measured with transcranial magnetic stimulation in children with epilepsy before and after antiepileptic drugs
- 2020
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Ingår i: Developmental Medicine and Child Neurology. - : Wiley. - 0012-1622 .- 1469-8749. ; 62:7, s. 793-798
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Tidskriftsartikel (refereegranskat)abstract
- Aim To evaluate cortical excitability with transcranial magnetic stimulation (TMS) in children with new-onset epilepsy before and after antiepileptic drugs (AEDs). Method Fifty-five drug-naive patients (29 females, 26 males; 3-18y), with new-onset epilepsy were recruited from 1st May 2014 to 31st October 2017 at the Child Neurology Department, Queen Silvia's Children's Hospital, Gothenburg, Sweden. We performed TMS in 48 children (23 females, 25 males; mean [SD] age 10y [3y], range 4-15y) with epilepsy (27 generalized and 21 focal) before and after the introduction of AEDs. We used single- and paired-pulse TMS. We used single-pulse TMS to record resting motor thresholds (RMTs), stimulus-response curves, and cortical silent periods (CSPs). We used paired-pulse TMS to record intracortical inhibition and facilitation at short, long, and intermediate intervals. Results There were no differences in cortical excitability between children with generalized and focal epilepsy at baseline. After AED treatment, RMTs increased (p=0.001), especially in children receiving sodium valproate (p=0.005). CSPs decreased after sodium valproate was administered (p=0.050). As in previous studies, we noted a negative correlation between RMT and age in our study cohort. Paired-pulse TMS could not be performed in most children because high RMTs made suprathreshold stimulation impossible. Interpretation Cortical excitability as measured with RMT decreased after the introduction of AEDs. This was seen in children with both generalized and focal epilepsy who were treated with sodium valproate, although it was most prominent in children with generalized epilepsy. We suggest that TMS might be used as a prognostic tool to predict AED efficacy.
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| 4. |
- Backman, Sofia, et al.
(författare)
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Swedish consensus reached on recording, interpretation and reporting of neonatal continuous simplified electroencephalography that is supported by amplitude-integrated trend analysis
- 2018
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Ingår i: Acta Paediatrica. - : WILEY. - 0803-5253 .- 1651-2227. ; 107:10, s. 1702-1709
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Tidskriftsartikel (refereegranskat)abstract
- Continuous monitoring of electroencephalography (EEG), with a focus on amplitude-integrated EEG (aEEG), has been used in neonatal intensive care for decades. A number of systems have been suggested for describing and quantifying aEEG patterns. Extensive full-montage EEG monitoring is used in specialised intensive care units. The American Clinical Neurophysiology Society published recommendations for defining and reporting EEG findings in critically ill adults and infants. Swedish neonatologists and clinical neurophysiologists collaborated to optimise simplified neonatal continuous aEEG and EEG recordings based on these American documents. Conclusion: This paper describes the Swedish consensus document produced by those meetings.
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| 5. |
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| 6. |
- Flisberg, Anders, 1958, et al.
(författare)
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Does indomethacin for closure of patent ductus arteriosus affect cerebral function?
- 2010
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Ingår i: Acta Paediatrica. - : Wiley. - 0803-5253 .- 1651-2227. ; 99:10, s. 1493-1497
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To study whether indomethacin used in conventional dose for closure of patent ductus arteriosus affects cerebral function measured by Electroencephalograms (EEG) evaluated by quantitative measures. Study design: Seven premature neonates with haemodynamically significant persistent ductus arteriosus were recruited. EEG were recorded before, during and after an intravenous infusion of 0.2 mg/kg indomethacin over 10 min. The EEG was analysed by two methods with different degrees of complexity for the amount of low-activity periods (LAP, "suppressions") as an indicator of affection of cerebral function. Results: Neither of the two methods identified any change in the amount of LAPs in the EEG as compared to before the indomethacin infusion. Conclusion: Indomethacin in conventional dose for closure of patent ductus arteriosus does not affect cerebral function as evaluated by quantitative EEG.
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| 7. |
- Flisberg, Anders, 1958, et al.
(författare)
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EEG and spectral edge frequency : analysis in posthypoxic newborn piglets
- 2010
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Ingår i: Neuro - endocrinology letters. - : Brain Research Promotion. - 0172-780X. ; 31:2, s. 181-186
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To evaluate the frequency content of the electroencephalogram (EEG) during recovery after a severe hypoxic insult in newborn piglets. METHODS: EEG was continuously monitored in nine newborn piglets exposed to a severe hypoxic period. Power spectra in five frequency bands were calculated using Fourier transformation. Spectral edge frequency 90 (SEF90) was defined as the frequency below which 90% of the power in the EEG was located. The piglets were divided into two groups; Group 1 represented piglets with some EEG recovery and Group 2 represented piglets without any EEG recovery. RESULTS: The recovery of the EEG in Group 1 had the same time course in all frequency bands. SEF90 indicates recovery earlier than the value of total power. But SEF90 also signals activity in the EEGs that were almost completely suppressed. When SEF90 was calculated during periods of periodic EEG activity during the very early phase of recovery, the values fell within the same range as during the control period. CONCLUSION: Spectral analysis of continuous EEG in newborn piglets exposed to very severe hypoxia showed that no specific frequency band of the EEG preceded the other ones during recovery. The results of the SEF90 measure, demonstrates the need for critical analysis of the raw EEG before any reliable estimation of cerebral function can be made.
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| 8. |
- Gu, Irene Yu-Hua, 1953, et al.
(författare)
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3D Limb Movement Tracking and Analysis for Neurological Dysfunctions of Neonates Using Multi-Camera Videos
- 2016
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Ingår i: Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS. - 1557-170X. - 9781457702204 ; 2016-October, s. 2395-2398
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Konferensbidrag (refereegranskat)abstract
- Central nervous system dysfunction in infants may be manifested through inconsistent, rigid and abnormal limb movements. Detection of limb movement anomalies associated with such neurological dysfunctions in infants is the first step towards early treatment for improving infant development. This paper addresses the issue of detecting and quantifying limb movement anomalies in infants through non-invasive 3D image analysis methods using videos from multiple camera views. We propose a novel scheme for tracking 3D time trajectories of markers on infant’s limbs by video analysis techniques. The proposed scheme employ videos captured from three camera views. This enables us to detect a set of enhanced 3D markers through cross-view matching and to effectively handle marker self-occlusions by other body parts. We track a set of 3D trajectories of limb movements by a set of particle filters in parallel, enabling more robust 3D tracking of markers, and use the 3D model errors for quantifying abrupt limb movements. The proposed work makes a significant advancement to the previous work in [1] through employing tracking in 3D space, and hence overcome several main barriers that hinder real applications by using single camera-based techniques. To the best of our knowledge, applying such a multi-view video analysis approach for assessing neurological dysfunctions of infants through 3D time trajectories of markers on limbs is novel, and could lead to computer-aided tools for diagnosis of dysfunctions where early treatment may improve infant development. Experiments were conducted on multi-view neonate videos recorded in a clinical setting and results have provided further support to the proposed method.
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| 9. |
- Hagberg, Henrik, 1955, et al.
(författare)
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Extracellular overflow of glutamate, aspartate, GABA and taurine in the cortex and basal ganglia of fetal lambs during hypoxia-ischemia.
- 1987
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Ingår i: Neuroscience letters. - 0304-3940. ; 78:3, s. 311-7
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Tidskriftsartikel (refereegranskat)abstract
- Extracellular levels of excitatory and inhibitory amino acids were measured in the cortex and striatum of asphyxiated fetal lambs. The fetus was exteriorized from the anesthetized ewe and dialysis probes were placed in the parietal cortex and caudate nucleus. Cerebral blood flow was measured with Xe-clearance. Cortical somatosensory-evoked potentials and electroencephalogram (EEG) were continuously recorded. Asphyxia was induced by clamping the umbilical cord or by graded compression of the maternal aorta. Asphyxia accompanied by elevated cerebral blood flow resulted in a moderate rise in extracellular amino acid levels. During extreme asphyxia, i.e. abolished evoked potentials and reduced cerebral blood flow, marked extracellular elevations of glutamate (3- to 11-fold), aspartate (3- to 7-fold), gamma-aminobutyric acid (GABA) (3- to 5-fold) and taurine (3- to 18-fold) occurred, the higher values representing striatum. Excessive levels of excitatory amino acids may exert injurious effects on immature neurons during such hypoxic-ischemic states.
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| 10. |
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| 11. |
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| 12. |
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| 13. |
- Löfgren, Nils, 1969, et al.
(författare)
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Spectral distance for ARMA models applied to electroencephalogram for early detection of hypoxia
- 2006
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Ingår i: Journal of Neural Engineering. - : IOP Publishing. - 1741-2560 .- 1741-2552. ; 3:3, s. 227-34
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Tidskriftsartikel (refereegranskat)abstract
- A novel measure of spectral distance is presented, which is inspired by the prediction residual parameter presented by Itakura in 1975, but derived from frequency domain data and extended to include autoregressive moving average (ARMA) models. This new algorithm is applied to electroencephalogram (EEG) data from newborn piglets exposed to hypoxia for the purpose of early detection of hypoxia. The performance is evaluated using parameters relevant for potential clinical use, and is found to outperform the Itakura distance, which has proved to be useful for this application. Additionally, we compare the performance with various algorithms previously used for the detection of hypoxia from EEG. Our results based on EEG from newborn piglets show that some detector statistics divert significantly from a reference period less than 2 min after the start of general hypoxia. Among these successful detectors, the proposed spectral distance is the only spectral-based parameter. It therefore appears that spectral changes due to hypoxia are best described by use of an ARMA- model-based spectral estimate, but the drawback of the presented method is high computational effort.
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| 14. |
- Löfhed, Johan, et al.
(författare)
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Soft textile electrodes for EEG monitoring
- 2010
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Konferensbidrag (refereegranskat)abstract
- There is a need for long term monitoring of the brain during intensive care. This is e.g. the case for newborn babies that have been exposed to hypoxia during delivery. Electroencephalography (EEG) is the technique of choice. To get a clear and detailed view of the brain activity a large number of EEG electrodes should be used. Applying traditional electrodes one by one is a time-consuming and technically demanding work and therefore electrode caps are sometimes used. The existing caps have however been found to be suboptimal for long term monitoring because they may induce too high a pressure on the scalp of the babies. We have tested three different types of textile electrodes with regard to their potential use for EEG monitoring. The results show that soft conducting textile materials can indeed be used for EEG monitoring.
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| 15. |
- Löfhede, Johan, 1978, et al.
(författare)
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Automatic classification of background EEG activity in healthy and sick neonates
- 2010
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Ingår i: Journal of Neural Engineering. - : IOP Publishing. - 1741-2560 .- 1741-2552. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- The overall aim of our research is to develop methods for a monitoring system to be used at neonatal intensive care units. When monitoring a baby, a range of different types of background activity needs to be considered. In this work, we have developed a scheme for automatic classification of background EEG activity in newborn babies. EEG from six full-term babies who were displaying a burst suppression pattern while suffering from the after-effects of asphyxia during birth was included along with EEG from 20 full-term healthy newborn babies. The signals from the healthy babies were divided into four behavioural states: active awake, quiet awake, active sleep and quiet sleep. By using a number of features extracted from the EEG together with Fisher’s linear discriminant classifier we have managed to achieve 100% correct classification when separating burst suppression EEG from all four healthy EEG types and 93% true positive classification when separating quiet sleep from the other types. The other three sleep stages could not be classified. When the pathological burst suppression pattern was detected, the analysis was taken one step further and the signal was segmented into burst and suppression, allowing clinically relevant parameters such as suppression length and burst suppression ratio to be calculated. The segmentation of the burst suppression EEG works well, with a probability of error around 4%.
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| 16. |
- Löfhede, Johan, et al.
(författare)
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Classification of burst and suppression in the neonatal electroencephalogram
- 2008
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Ingår i: Journal of Neural Engineering. - : Institute of Physics Publishing Ltd.. - 1741-2560 .- 1741-2552. ; 5:4, s. 402-410
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Tidskriftsartikel (refereegranskat)abstract
- Fisher's linear discriminant (FLD), a feed-forward artificial neural network (ANN) and a support vector machine (SVM) were compared with respect to their ability to distinguish bursts from suppressions in electroencephalograms (EEG) displaying a burst-suppression pattern. Five features extracted from the EEG were used as inputs. The study was based on EEG signals from six full-term infants who had suffered from perinatal asphyxia, and the methods have been trained with reference data classified by an experienced electroencephalographer. The results are summarized as the area under the curve (AUC), derived from receiver operating characteristic (ROC) curves for the three methods. Based on this, the SVM performs slightly better than the others. Testing the three methods with combinations of increasing numbers of the five features shows that the SVM handles the increasing amount of information better than the other methods.
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| 17. |
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| 18. |
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| 19. |
- Löfhede, Johan, 1978, et al.
(författare)
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Classifying neonatal EEG
- 2007
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Ingår i: Proceedings of Medicinteknikdagarna 2007. Annual conference of Svensk Förening för Medicinsk Teknik och Fysik. Oct, 2007. Örebro..
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In spite of considerable medical progress during the last decades, the perinatal period is still one of the high-risk periods in any individual’s lifetime. In neonatal intensive care of today there is a serious lack of methods that allow continuous monitoring of cerebral function. While we consider it mandatory that good quality hospital care shall include facilities for continuous monitoring of respiratory and cardiac functions in severely ill patients we lack the same possibility when it comes to this most important organ of the body, the brain. The electroencephalogram (EEG) can provide information regarding the state of the brain, but is in its current form not suited for continuous monitoring. Not all neonatal EEG characteristics have been fully investigated or are fully understood, and the people with the necessary competence for interpreting them is not available at neonatal intensive care wards. Our approach is to design a decision support system suitable for continuous monitoring that uses classification algorithms to classify the EEG, for example as normal continuous, normal periodic and pathologic periodic. The EEG is a highly complex signal, and rather than estimating a single parameter, the focus has been on applying classification methods on ensembles of parameters that describe the characteristics of the EEG signal. These parameters have been chosen to enhance different aspects of the EEG signal, and by training classification algorithms with manually segmented data characteristic differences between these complex signals can be found. So far, various classification algorithms have been tested on the task of classifying segments of burst-suppression EEG (pathological periodic) into burst and suppression with rather satisfying results. As a next step we have planned to look into the classification of EEG signals as continuous and periodic, and classification of periodic signals as pathological or normal.
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| 20. |
- Löfhede, Johan, et al.
(författare)
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Comparing a Supervised and an Unsupervised Classification Method for Burst Detection in Neonatal EEG
- 2008
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Ingår i: Proceedings of Engineering in Medicine and Biology Society, EMBS 2008. 30th Annual International Conference of the IEEE, 20-24 August, 2008. - : IEEE. - 1557-170X. - 9781424418145 ; , s. 3836-3839
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Konferensbidrag (refereegranskat)abstract
- Hidden Markov Models (HMM) and Support Vector Machines (SVM) using unsupervised and supervised training, respectively, were compared with respect to their ability to correctly classify burst and suppression in neonatal EEG. Each classifier was fed five feature signals extracted from EEG signals from six full term infants who had suffered from perinatal asphyxia. Visual inspection of the EEG by an experienced electroencephalographer was used as the gold standard when training the SVM, and for evaluating the performance of both methods. The results are presented as receiver operating characteristic (ROC) curves and quantified by the area under the curve (AUC). Our study show that the SVM and the HMM exhibit similar performance, despite their fundamental differences.
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| 21. |
- Löfhede, Johan, 1978, et al.
(författare)
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Comparison of Three Methods for Classifying Burst and Suppression in the EEG of Post Asphyctic Newborns
- 2007
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Ingår i: Engineering in Medicine and Biology Society, 2007. EMBS 2007. 29th Annual International Conference of the IEEE. - : IEEE. - 1557-170X. - 9781424407880 - 9781424407873 ; , s. 5136-5139
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Konferensbidrag (refereegranskat)abstract
- Fisher's linear discriminant, a feed-forward neural network (NN) and a support vector machine (SVM) are compared with respect to their ability to distinguish bursts from suppression in burst-suppression electroencephalogram (EEG) signals using five features inherent in the EEG as input. The study is based on EEG signals from six full term infants who have suffered from perinatal asphyxia, and the methods have been trained with reference data classified by an experienced electroencephalographer. The results are summarized as area under the curve (AUC) values derived from receiver operating characteristic (ROC) curves for the three methods, and show that the SVM is slightly better than the others, at the cost of a higher computational complexity.
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| 22. |
- Löfhede, Johan, 1978, et al.
(författare)
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Detection of bursts in the EEG of post asphyctic newborns
- 2006
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Ingår i: 2006 28th Annual International Conference of the IEEE Engineering in Medicine and Biology Society. - 1557-170X. - 9781424400324 ; , s. 2179-2182, s. 5-6
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Konferensbidrag (refereegranskat)abstract
- Eight features inherent in the electroencephalogram (EEG) have been extracted and evaluated with respect to their ability to distinguish bursts from suppression in burst-suppression EEG. The study is based on EEG from six full term infants who had suffered from lack of oxygen during birth. The features were used as input in a neural network, which was trained on reference data segmented by an experienced electroencephalographer. The performance was then evaluated on validation data for each feature separately and in combinations. The results show that there are significant variations in the type of activity found in burst-suppression EEG from different subjects, and that while one or a few features seem to be sufficient for most patients in this group, some cases require specific combinations of features for good detection to be possible.
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| 23. |
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| 24. |
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| 25. |
- Löfhede, Johan, 1978, et al.
(författare)
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Soft Textile Electrodes for EEG Monitoring
- 2010
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Ingår i: [12]10th IEEE International Conference on Information Technology and Applications.
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Konferensbidrag (refereegranskat)
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| 26. |
- Löfhede, Johan, 1980-, et al.
(författare)
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Textile Electrodes for EEG Recording : A Pilot Study
- 2012
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Ingår i: Sensors. - Basel : MDPI. - 1424-8220. ; 12:12, s. 16907-16919
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Tidskriftsartikel (refereegranskat)abstract
- The overall aim of our research is to develop a monitoring system for neonatal intensive care units. Long-term EEG monitoring in newborns require that the electrodes don’t harm the sensitive skin of the baby, an especially relevant feature for premature babies. Our approach to EEG monitoring is based on several electrodes distributed over the head of the baby, and since the weight of the head always will be on some of them, any type of hard electrode will inevitably cause a pressure-point that can irritate the skin. Therefore, we propose the use of soft conductive textiles as EEG electrodes, primarily for neonates, but also for other kinds of unobtrusive long-term monitoring. In this paper we have tested two types of textile electrodes on five healthy adults and compared them to standard high quality electrodes. The acquired signals were compared with respect to morphology, frequency distribution, spectral coherence, correlation and power line interference sensitivity, and the signals were found to be similar in most respects. The good measurement performance exhibited by the textile electrodes indicates that they are feasible candidates for EEG recording, opening the door for long-term EEG monitoring applications.
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| 27. |
- Nyman, Erika, et al.
(författare)
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Neuroplasticity following Nerve Transfer of the Anterior Interosseous Nerve for Proximal Ulnar Nerve Injuries
- 2021
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Ingår i: Plastic and Reconstructive Surgery - Global Open. - : Lippincott, Williams & Wilkins. - 2169-7574. ; 9:7
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Tidskriftsartikel (refereegranskat)abstract
- Background: Injuries to the ulnar nerve at or above proximal forearm level result in poor recovery despite early microsurgical repair, especially concerning the intrinsic motor function of the hand. To augment the numbers of regenerating axons into the targeted muscles, a nerve transfer of the distal branch of the median nerve, the anterior interosseous nerve, to the ulnar motor branch has been described. Methods: Two patients with severe atrophy of the intrinsic hand muscles following an initial proximal ulnar nerve repair had surgery with an end-to-side transfer of the anterior interosseous nerve to the ulnar motor branch at the wrist level. Outcome and neuroplasticity were prospectively studied using questionnaires, clinical examinations, electroneurography, electromyography, somatosensory evoked potentials at pre nerve transfer and 3-, 12-, and 24-months post nerve transfer as well as navigated transcranial magnetic stimulation at pre nerve transfer and 3- and 12-months post nerve transfer. Results: Successively improved motor function was observed. Complete reinnervation of intrinsic hand muscles was demonstrated at 12- to 24-months follow-up by electroneurography and electromyography. At the cortical level, navigated transcranial magnetic stimulation detected a movement of the hot-spot for the abductor digiti mini muscle, originally innervated by the ulnar nerve and the size of the area from where responses could be elicited in this muscle changed over time, indicating central plastic processes. An almost complete reinnervation of the pronator quadratus muscle was also observed. Conclusion: Both central and peripheral plastic mechanisms are involved in muscle reinnervation after anterior interosseous nerve transfer for treatment of proximal ulnar nerve injuries.
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| 28. |
- Persson, Mikael, 1959, et al.
(författare)
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Advances in Neuro Diagnostic based on Microwave Technology, Transcranial Magnetic Stimulation and EEG source localization
- 2011
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Ingår i: Asia Pacific Microwave Conference, (APMC 2011;Melbourne, VIC; 5 - 8 December 2011). - 9780858259744 ; , s. 469-472
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Konferensbidrag (refereegranskat)abstract
- Advances in neuro diagnostics based on microwave antenna system in terms of a helmet including a set of broad band patch antennas is presented. It is shown that classification algorithms can be used to detect internal bleeding in stroke patients. Transcranial magnetic stimulation has traditionally been used for brain mapping and treatment of depression. In this paper we discuss the use of the method for neuro diagnostics with the help of integrated image guidance. Surgical therapy has become an important therapeutic alternative for some patients with medically intractable epilepsy. Electroencephalography and the associated model based diagnostics as a non-invasive diagnostic tool is also discussed.
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| 29. |
- Rahin, Hedayat, et al.
(författare)
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Effect of Transcutaneous Spinal Direct Current Stimulation in Patients with Painful Polyneuropathy and Influence of Possible Predictors of Efficacy including BDNF Polymorphism: A Randomized, Sham-Controlled Crossover Study
- 2023
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Ingår i: Brain Sciences. - : MDPI. - 2076-3425. ; 13:2
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: The neuromodulating effects of transcutaneous-spinal Direct Current Stimulation (tsDCS) have been reported to block pain signaling. For patients with chronic pain, tsDCS could be a potential treatment option. To approach this, we studied the effect of anodal tsDCS on patients with neuropathic pain approaching an optimal paradigm including the investigation of different outcome predictors. Methods: In this randomized, double-blinded, sham-controlled crossover study we recruited twenty patients with neurophysiologically evaluated neuropathic pain due to polyneuropathy (PNP). Variables (VAS; pain and sleep quality) were reported daily, one week prior to, and one week after the stimulation/sham period. Anodal tsDCS (2.5 mA, 20 min) was given once daily for three days during one week. BDNF-polymorphism, pharmacological treatment, and body mass index (BMI) of all the patients were investigated. Results: Comparing the effects of sham and real stimulation at the group level, there was a tendency towards reduced pain, but no significant effects were found. However, for sleep quality a significant improvement was seen. At the individual level, 30 and 35% of the subjects had a clinically significant improvement of pain level and sleep quality, respectively, the first day after the stimulation. Both effects were reduced over the coming week and these changes were negatively correlated. The BDNF polymorphism Val66Met was carried by 35% of the patients and this group was found to have a lower general level of pain but there was no significant difference in the tsDCS response effect. Neither pharmacologic treatment or BMI influenced the treatment effect. Conclusions: Short-term and sparse anodal thoracic tsDCS reduces pain and improves sleep with large inter-individual differences. Roughly 30% will benefit in a clinically meaningful way. The BDNF genotype seems to influence the level of pain that PNP produces. Individualized and intensified tsDCS may be a treatment option for neuropathic pain due to PNP.
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| 30. |
- Rådman, Lisa, 1983-
(författare)
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Effects of electrical accidents : occupational and health perspectives
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Professionals working in the electrical industry are at risk of accidental injuries caused by electricity. Electrical accidents can cause persistent neurological symptoms, previously mainly described in patients whose injuries were initially extensive. The overall aim of this thesis was to study the prevalence of persisting, self-reported symptoms after electrical accidents and to explore their relationship to results obtained using clinical methods that are commonly used to study nerve function and hand-arm function. Another aim was to increase knowledge about the work situation and the safety culture of Swedish electricians and to describe the frequency with which electricians seek health care after electrical accidents. Study I was a retrospective survey of 523 Swedish male electricians. In study II, the electricians who reported persistent symptoms were further invited to undergo clinical examinations that included quantitative sensory testing (QST), assessment of fine motor skills and tactile gnosis. The most common self-reported symptoms were pain, reduced sensation and reduced muscle function. For a few, these symptoms persisted at the time of survey. Roughly half of the group exhibited abnormal warm and cold perception thresholds and tactile gnosis test values. Study III included 24 participants with persisting self-reported sensory symptoms, 1-5 years after an accident. Observations of nerve function; QST, laserevoked potentials (LEP) and nerve conductions studies, were performed. At least one neurosensory impairment was present- in at least one of the tests in 67% of the participants. The participants in study III were also evaluated in study IV, in which a control group of 24 healthy persons was added. Hand function was affected in many participants assessed with the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire as was tactil gnosis and manual dexterity, for the participants in the case group. Only a quarter of the participants in study I sought health care after their accidents, and the safety culture questionnaire revealed deficiencies, particularly in the reporting culture. The conclusions of this thesis are that self-reported neurosensory symptoms can persist for years after an electrical accident and that these symptoms can be evaluated using standard neurophysiological and functional tests that reflect changes in nerve function. Accordingly, hand function, examined using both objective and subjective measures, may be affected after work-related electrical accidents. This thesis highlights some aspects of safety culture and the work situations of professionals within the electrical industry. These areas need to be improved so that reporting routines provide opportunities to learn from and prevent accidents.
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| 31. |
- Rådman, Lisa, 1983-, et al.
(författare)
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Hand function after an electrical accident : a case-control study
- 2023
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Ingår i: Journal of Occupational and Environmental Medicine. - : Lippincott Williams & Wilkins. - 1076-2752 .- 1536-5948. ; 65:3, s. 242-248
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Electrical accidents cause both acute and long-term injuries. The care of acute injuries is somewhat standardized, but currently recommendations or assessment tools are not available for assessing the long-term effects of an accident on hand function.METHODS: A case-control study of 24 healthy controls and 24 cases, 1-5 years after an electrical accident and with self-reported neurosensory symptoms, was performed using three hand-function tests: the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire, the Purdue Pegboard test and the Shape and Identification (STI) test.RESULTS: Compared to the control group, patients received statistically significantly lower scores for the DASH outcome measure and the Purdue Pegboard and for one finger on the STI test.CONCLUSION: Hand function is affected after an electrical accident in individuals with self-reported neurosensory symptoms.
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| 32. |
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| 33. |
- Selassie, G. R. H., et al.
(författare)
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Navigated transcranial magnetic stimulation for preoperative cortical mapping of expressive language in children: Development of a method
- 2018
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Ingår i: Epilepsy & Behavior. - : Elsevier BV. - 1525-5050 .- 1525-5069. ; 87, s. 180-187
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Tidskriftsartikel (refereegranskat)abstract
- We adjusted an object-naming task with repetitive navigated transcranial magnetic stimulation (rnTMS) originally developed for preoperative cortical language mapping in adults in order for it to be used in children. Two series of pictures were chosen for children above and below 10 years of age, respectively. Firstly, the series of pictures and the preferred speed of presentation were assessed for their applicability in children of different ages and abilities. Secondly, these series were used with rnTMS preoperatively in five children with epilepsy. Naming errors induced by the stimulation comprised no response, delayed response, semantic error, phonological error, and self-correction. Language laterality was compared with the results of a dichotic listening test and with neuropsychological tests with respect to general laterality, and general language abilities were considered with respect to the results of stimulation. One participant had below normal general language abilities, two had below-normal rapid naming, and three had slow and indistinct articulation. Laterality was only clear in two of the participants. All children required breaks of various durations during the process, and individual adjustments of the interpicture interval and other stimulation parameters were also made. We conclude that, after adjustment, rnTMS combined with an object-naming task can be useful for preoperative language mapping in children.
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| 34. |
- Svantesson, Mats, 1975-, et al.
(författare)
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Get a New Perspective on EEG: Convolutional Neural Network Encoders for Parametric t-SNE
- 2023
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Ingår i: Brain Sciences. - : MDPI. - 2076-3425. ; 13:3
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Tidskriftsartikel (refereegranskat)abstract
- t-distributed stochastic neighbor embedding (t-SNE) is a method for reducing high-dimensional data to a low-dimensional representation, and is mostly used for visualizing data. In parametric t-SNE, a neural network learns to reproduce this mapping. When used for EEG analysis, the data are usually first transformed into a set of features, but it is not known which features are optimal. The principle of t-SNE was used to train convolutional neural network (CNN) encoders to learn to produce both a high- and a low-dimensional representation, eliminating the need for feature engineering. To evaluate the method, the Temple University EEG Corpus was used to create three datasets with distinct EEG characters: (1) wakefulness and sleep; (2) interictal epileptiform discharges; and (3) seizure activity. The CNN encoders produced low-dimensional representations of the datasets with a structure that conformed well to the EEG characters and generalized to new data. Compared to parametric t-SNE for either a short-time Fourier transform or wavelet representation of the datasets, the developed CNN encoders performed equally well in separating categories, as assessed by support vector machines. The CNN encoders generally produced a higher degree of clustering, both visually and in the number of clusters detected by k-means clustering. The developed principle is promising and could be further developed to create general tools for exploring relations in EEG data.
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| 35. |
- Svantesson, Mats, 1975-
(författare)
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Self-supervised deep learning and EEG categorization
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Deep learning has the potential to be used to improve and streamline EEG analysis. At the present, classifiers and supervised learning dominate the field. Supervised learning depends on target labels which most often are created by human experts manually classifying data. A problem with supervised learning is intra- and interrater agreement which in some instances are far from perfect. This can affect the training and make evaluation more difficult. This thesis includes three papers where self-supervised deep neural networks were developed. In self-supervised learning, the input data to the networks themselves contain structures that are used as targets for the training and no labeling is necessary. In paper I, deep neural networks were trained to increase the number of-, or to recreate missing EEG-channels. The performance was at least on the same level as that of spherical interpolation, but unlike in the case of interpolation, missing data does not have to be identified manually first. Papers II and III involved developing deep neural networks for clustering analysis. The networks produced two-dimensional representations of EEG data and the training strategy was based on the principle of t-distributed stochastic neighbor embedding (t-SNE). In paper II, comparisons were made to parametric t-SNE and EEG-features obtained from time-frequency methods. The deep neural networks produced more distinct clustering when tested on data annotated for epileptiform discharges, seizure activity, or sleep-wakefulness.In paper III, the newly developed method was used to compare annotations of epileptiform discharges. Two experts performed independent annotations and classifiers were trained on these, using supervised learning, which in turn produced new annotations. The agreement when comparing two sets of annotations was not larger between the two experts than between an expert and a classifier. The analysis showed that differences in the annotations by the experts influenced the training of the classifiers. However, the clustering analysis indicated that although it was not always the exact same waveforms that were assessed as epileptiform discharges, they were often similar.The work thus resulted in different methods to process and analyze EEG data, which may have practical usefulness. Traditional agreement scores only assess the exact agreement. However, they reveal nothing about the nature of disagreement. Cluster analysis can provide a means to perform this assessment.
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| 36. |
- Svantesson, Mats, 1975-, et al.
(författare)
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Virtual EEG-electrodes : Convolutional neural networks as a method for upsampling or restoring channels
- 2021
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Ingår i: Journal of Neuroscience Methods. - : Elsevier. - 0165-0270 .- 1872-678X.
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundIn clinical practice, EEGs are assessed visually. For practical reasons, recordings often need to be performed with a reduced number of electrodes and artifacts make assessment difficult. To circumvent these obstacles, different interpolation techniques can be utilized. These techniques usually perform better for higher electrode densities and values interpolated at areas far from electrodes can be unreliable. Using a method that learns the statistical distribution of the cortical electrical fields and predicts values may yield better results.New MethodGenerative networks based on convolutional layers were trained to upsample from 4 or 14 channels or to dynamically restore single missing channels to recreate 21-channel EEGs. 5,144 h of data from 1,385 subjects of the Temple University Hospital EEG database were used for training and evaluating the networks.Comparison with Existing MethodThe results were compared to spherical spline interpolation. Several statistical measures were used as well as a visual evaluation by board certified clinical neurophysiologists. Overall, the generative networks performed significantly better. There was no difference between real and network generated data in the number of examples assessed as artificial by experienced EEG interpreters whereas for data generated by interpolation, the number was significantly higher. In addition, network performance improved with increasing number of included subjects, with the greatest effect seen in the range 5–100 subjects.ConclusionsUsing neural networks to restore or upsample EEG signals is a viable alternative to spherical spline interpolation.
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| 37. |
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| 38. |
- Thordstein, Magnus, et al.
(författare)
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Effect of transspinal direct current stimulation on afferent pain signalling in humans
- 2020
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Ingår i: Journal of clinical neuroscience. - : ELSEVIER SCI LTD. - 0967-5868 .- 1532-2653. ; 77, s. 163-167
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Tidskriftsartikel (refereegranskat)abstract
- Anodal transspinal Direct Current Stimulation (tsDCS) has been suggested as a means to treat neuropathic pain by reducing pain signalling/processing and Laser Evoked Potentials (LEPs) likewise as a method to evaluate such reduction. However, results in previous studies are disagreeing. To evaluate these claims using rigorous methodology, LEPs were evoked from hands and feet in healthy volunteers. The N2 potential and three psychophysic parameters (general- and pinprick pain, warmth) were used to evaluate the signalling and appreciation of pain respectively. This was made at three time points; at baseline, directly- and 30 min after low thoracic tsDCS (20 min, 2.5 mA, cathode on shoulder). The study was randomized, cross over, double blinded and placebo controlled. At the group level low thoracic anodal tsDCS produced reduced perceptions of all three tested pain qualities from the foot (p < 0.05 - p < 0.001). These reductions began during stimulation and became more pronounced during the 30 min after its cessation (p < 0.05 - p < 0.01). The LEP parameter alteration mirroring these changes was latency prolongation (p < 0.05 - p < 0.001) whereas amplitude reductions were in par with placebo stimulation. Similar but less pronounced and only transient (during stimulation, p < 0.05 - p < 0.001) changes, were seen for hand stimulation. The interindividual variation was large. The findings indicate that anodal tsDCS may become a technique to treat neuropathic pain by reducing pain signalling/processing and LEPs likewise a method to evaluate such reduction. (C) 2020 Elsevier Ltd. All rights reserved.
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| 39. |
- Thordstein, Magnus, et al.
(författare)
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Effects of inflammation on cerebral electric activity in fetal sheep
- 2008
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Ingår i: 2nd Congress of the European Academy of Paediatrics, Nice 23-28 okt 2008.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- OBJECTIVE Intrauterine infections can by themselves induce fetal brain damage but also potentiate the effects of other harmful influences such as asphyxia and seizures. Using an EEG technique that permits the recording of extremely low frequencies, often called DC EEG, changes in the level, i.e. DC shifts can be detected. The DC level has been suggested to depend mainly on the potential over the blood brain barrier (BBB), in turn decided primarily by the arterial level of pCO2. Fetuses affected by infection/inflammation that produce detrimental effects on the brain, may have elevated levels of pCO2 and disturbance of the BBB. We aimed at investigating the possibility that the DC EEG could be used to detect the effects of inflammation on the fetal brain. METHODS Fetal sheep were instrumented at 97 days of gestation with catheters, four active EEG electrodes placed on the dura mater as well as extracranial reference and ground electrodes. After three days of recovery, the bacterial endotoxin lipopolysaccharide (LPS) was given to the fetus (200 ng i.v.). RESULTS Exposure to LPS induced a positive DC shift in parallel to the assumed affection of cerebral function and to the pCO2 elevation. This change was not always obvious in standard EEG. CONCLUSIONS These recordings of fetal DC EEG appear to be the first to be done. They indicate that the effects of inflammation on cerebral function can be monitored by DC EEG. Such monitoring might be feasible also during late stages of labour and in neonates.
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| 40. |
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| 41. |
- Thordstein, Magnus, et al.
(författare)
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Effects of inflammation on cerebral electric activity in fetal sheep
- 2007
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Ingår i: Sjätte Graz-symposiet om utvecklings-neurologi, Graz 3-5 maj 2007.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- OBJECTIVEIntrauterine infections can by themselves induce fetal brain damage but also potentiate the effects of other harmful influences such as asphyxia and seizures. Using an EEG technique that permits the recording of extremely low frequencies, often called DC EEG, changes in the level, i.e. DC shifts can be detected. The DC level has been suggested to depend mainly on the potential over the blood brain barrier (BBB), in turn decided primarily by the arterial level of pCO2.Fetuses affected by infection/inflammation that produce detrimental effects on the brain, may have elevated levels of pCO2 and disturbance of the BBB. We aimed at investigating the possibility that the DC EEG could be used to detect the effects of inflammation on the fetal brain.METHODSFetal sheep were instrumented at 97 days of gestation with catheters, four active EEG electrodes placed on the dura mater as well as extracranial reference and ground electrodes. After three days of recovery, the bacterial endotoxin lipopolysaccharide (LPS) was given to the fetus (200 ng i.v.).RESULTSExposure to LPS induced a positive DC shift in parallel to the assumed affection of cerebral function and to the pCO2 elevation. This change was not always obvious in standard EEG.CONCLUSIONSThese recordings of fetal DC EEG appear to be the first to be done. They indicate that the effects of inflammation on cerebral function can be monitored by DC EEG. Such monitoring might be feasible also during late stages of labour and in neonates.
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| 42. |
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| 43. |
- Thordstein, Magnus, et al.
(författare)
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Individual effects of varying stimulation intensity and response criteria on area of activation for different muscles in humans. A study using navigated transcranial magnetic stimulation
- 2013
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Ingår i: Brain Stimulation. - : Elsevier BV. - 1935-861X. ; 6:1, s. 49-53
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Tidskriftsartikel (refereegranskat)abstract
- Background When using transcranial magnetic stimulation, a stimulation intensity defined as a certain level above the threshold for activation of a hand muscle is commonly used, disregarding the fact that the areas of activation for different muscles may have varying response characteristics intra- and interindividually. Objective To study the response characteristics of different muscles and compare them within and between individuals. Also to investigate the effect of varying stimulation intensity (defined in two different ways) and amplitude criterion for response, on the sizes of the activation areas for different muscles. Methods A system of transcranial magnetic stimulation with navigation capacity where the stimulation intensity can be defined in terms of the electric field strength in the tissue was used. Four different muscles were investigated in healthy adults. The threshold for activation at rest (RMT) of the different muscles and their respective areas of activation were quantified using three different stimulus intensities (100, 110 and 120% RMT) and two criteria for response amplitude (20 and 50 μV). Results Responses could readily be determined using 20 μV as response limit. The RMTs for different muscles varied within and between individuals. The degree to which the area depended on stimulation intensity differed between muscles intra- and interindividually. All results were statistically significant (P < 0.05 or less). Conclusions The response characteristics vary between muscles within an individual and between individuals for a certain muscle. Thus, for optimal accuracy when delineating the activation area, the investigation should be adapted to each particular muscle.
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| 44. |
- Thordstein, Magnus, et al.
(författare)
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Infraslow EEG activity in burst periods from post asphyctic full term neonates
- 2005
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Ingår i: Clinical Neurophysiology. - : Elsevier BV. - 1388-2457 .- 1872-8952. ; 116:7, s. 1501-6
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To investigate whether very low EEG frequency activity can be recorded from post asphyctic full term neonates using EEG equipment where the high pass filter level was lowered to 0.05 Hz. METHODS: The time constant of the amplifier hardware was set to 3.2 s in order to enable recordings that equal to a high pass filter cut off at 0.05 Hz. Burst episodes were selected from the EEGs of 5 post asphyctic full term neonates. The episodes were analysed visually using different montages and subjected to power spectrum analysis. Powers in two bands were estimated; 0-1 and 1-4 Hz, designated very low- and low-frequency activity, respectively (VLFA, LFA). RESULTS: In all infants, VLFA coinciding with the burst episodes could be detected. The duration of the VLFA was about the same as that of the burst episode i.e. around 4s. The activity was most prominent over the posterior regions. In this small material, a large amount of VLFA neonatally seemed to possibly be related to a more favourable prognosis. CONCLUSIONS: VLFA can be recorded from post asphyctic full term neonates using EEG equipment with lowered cut off frequency for the high pass filter. SIGNIFICANCE: VLFA normally disregarded due to filtering, is present in the EEG of sick neonates and may carry important clinical information.
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| 45. |
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| 46. |
- Thordstein, Magnus, et al.
(författare)
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Possibly lifesaving, noninvasive, EEG-guided neuromodulation in anesthesia-refractory partial status epilepticus
- 2012
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Ingår i: Epilepsy & Behavior. - : Elsevier BV. - 1525-5050. ; 25:3, s. 468-472
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Tidskriftsartikel (refereegranskat)abstract
- This study aimed to investigate the effect of low frequency repetitive transcranial magnetic stimulation (rTMS) guided as to localization and effect by continuous EEG on a super-refractory status epilepticus unresponsive to conventional treatment for 44 days including repeated deep sedation. Repetitive transcranial magnetic stimulation was delivered for one-hour sessions to the most active of two EEG foci for 8 days. From the third day of stimulation, the EEG pathology markedly decreased in parallel to clinical improvement. The patient could be weaned off the respirator, transferred to an ordinary ward then to a rehabilitation clinic. This is the first report of a positive outcome of rTMS treatment in super-refractory status epilepticus. In the context of refractory partial status epilepticus, neuromodulation through rTMS is a safe treatment option. If performed along the lines herein described, it may also be more efficient than conventional treatment. Repetitive transcranial magnetic stimulation may be an underused treatment option for status epilepticus. (C) 2012 Elsevier Inc. All rights reserved.
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| 47. |
- Thordstein, Magnus, et al.
(författare)
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Sex differences in electrocortical activity in human neonates
- 2006
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Ingår i: Neuroreport. - : Ovid Technologies (Wolters Kluwer Health). - 0959-4965 .- 1473-558X. ; 17:11, s. 1165-8
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Tidskriftsartikel (refereegranskat)abstract
- Cerebral cortical activity in healthy, full-term human neonates (10 boys and 10 girls) was evaluated using spectral estimation of electroencephalogram frequency content with new equipment and analysis technique allowing the assessment of the lowest frequencies (i.e. infraslow waves). The activity was analysed under quiet sleep and active wakefulness taking sex into consideration. During sleep, the mean amount of infraslow activity was 27% larger in boys, whereas during wakefulness the average amount of higher frequencies was 17% larger in girls. Both these differences indicate an earlier maturation of cortical function in girls than in boys.
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| 48. |
- Thordstein, Magnus, et al.
(författare)
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Spectral analysis of burst periods in EEG from healthy and post-asphyctic full-term neonates
- 2004
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Ingår i: Clin Neurophysiol. - : Elsevier BV. - 1388-2457 .- 1872-8952. ; 115:11, s. 2461-6
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To investigate whether the periodic EEG patterns seen in healthy and sick full term neonates (trace alternant and burst suppression, respectively) have different frequency characteristics. METHODS: Burst episodes were selected from the EEGs of 9 healthy and 9 post-asphyctic full-term neonates and subjected to power spectrum analysis. Powers in two bands were estimated; 0-4 and 4-30 Hz, designated low- and high-frequency activity, respectively (LFA, HFA). The spectral edge frequency (SEF) was also assessed. RESULTS: In bursts, the LFA power was lower in periods of burst suppression as compared to those of trace alternant. The parameter that best discriminated between the groups was the relative amount of low- and high-frequency activity. The SEF parameter had a low sensitivity to the group differences. In healthy neonates, the LFA power was higher over the posterior right as compared to the posterior left region. CONCLUSIONS: Spectral power of low frequencies differs significantly between the burst episodes of healthy and sick neonates. SIGNIFICANCE: These results can be used when monitoring cerebral function in neonates.
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| 49. |
- Thordstein, Magnus, et al.
(författare)
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The difficulty of appreciating slowness
- 2006
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Ingår i: Clinical Neurophysiology. - : Elsevier BV. - 1388-2457 .- 1872-8952. ; 117:4, s. 929-930
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Tidskriftsartikel (refereegranskat)
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| 50. |
- Thordstein, Magnus, et al.
(författare)
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Transfer of cortical motor representation after a perinatal cerebral insult.
- 2011
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Ingår i: Pediatric neurology. - : Elsevier BV. - 1873-5150 .- 0887-8994. ; 44:2, s. 131-4
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Tidskriftsartikel (refereegranskat)abstract
- In a 16-year-old boy with hemiplegia and severe, intractable epilepsy after a neonatal cerebral ischemic insult, cortical motor control was only equivocally assessed by functional magnetic resonance imaging. Therefore, high-precision navigated transcranial magnetic stimulation was performed, which demonstrated that cortical control of muscles on the paretic side was selectively affected. Leg muscle control was located in the contralateral hemisphere, as expected in healthy individuals, whereas forearm muscles were controlled from both hemispheres, and hand muscles were controlled only from the hemisphere ipsilateral to the paresis.
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