| 1. |
- 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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| 2. |
- 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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| 3. |
- 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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| 4. |
- 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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| 5. |
- 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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| 6. |
- 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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| 7. |
- 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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| 8. |
- 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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| 9. |
- 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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| 10. |
- Wahlgren, Carl, et al.
(författare)
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Prevalence of discomplete sensorimotor spinal cord injury as evidenced by neurophysiological methods : A cross-sectional study
- 2021
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Ingår i: Journal of Rehabilitation Medicine. - Uppsala, Sweden : Stiftelsen Rehabiliteringsinformation. - 1650-1977 .- 1651-2081. ; 53:2
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: To assess the prevalence of residual trans-lesion connectivity in persons with chronic clinically complete spinal cord injury (discompleteness) by neurophysiological methods.PARTICIPANTS: A total of 23 adults with chronic sensorimotor complete spinal cord injury, identified through regional registries the regional spinal cord registry of Östergötland, Sweden.METHODS: Diagnosis of clinically complete spinal cord injury was verified by standardized neurological examination. Then, a neurophysiological examination was performed, comprising electroneurography, electromyography, sympathetic skin response and evoked potentials (sensory, laser and motor). Based on this assessment, a composite outcome measure, indicating either strong, possible or no evidence of discomplete spinal cord injury, was formed.RESULTS: Strong neurophysiological evidence of discomplete spinal cord injury was found in 17% (4/23) of participants. If also accepting "possible evidence", the discomplete group comprised 39% (9/23). The remaining 61% showed no neurophysiological evidence of discompleteness. However, if also counting reports of subjective sensation elicited during neurophysiological testing in the absence of objective findings, 52% (12/23) showed indication of discomplete spinal cord injury.CONCLUSION: Evidence of discomplete spinal cord injury can be demonstrated using standard neurophysiological techniques in a substantial subset of individuals with clinically complete spinal cord injury. This study adds to the evidence base indicating the potential of various modes of cross-lesional sensorimotor functional restoration in some cases of chronic clinically complete spinal cord injury.
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| 11. |
- Wold, Andrew, et al.
(författare)
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Clinical Evaluation of Nerve Function in Electrical Accident Survivors with Persisting Neurosensory Symptoms
- 2022
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Ingår i: Brain Sciences. - : MDPI. - 2076-3425. ; 12:10
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Work related electrical accidents are prevalent and can cause persisting symptoms. We used clinical neurophysiological techniques to assess neurosensory function following electrical accidents and correlated test results with the patients' symptoms.METHODS: We studied 24 patients who reported persisting neurosensory symptoms following a workplace electrical accident. We assessed nerve function using quantitative sensory testing (QST), thermal roller testing, laser evoked potential (LEP), and electroneurography. The patients' results were compared with previously established normative data.RESULTS: Altogether, 67% of the patients showed at least one neurosensory impairment with a large heterogeneity in test results across patients. At a group level, we observed significant deviations in in QST, LEP, and sensory and motor neurography. Overall, we found a weak correlation between test results and self-reported symptoms.CONCLUSIONS: In a majority of patients with neurosensory symptoms after a workplace electrical accident, neurosensory testing confirmed the existence of an underlying impairment of the nervous system.
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| 12. |
- Wold, Andrew, et al.
(författare)
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Just Breathe: Improving LEP Outcomes through Long Interval Breathing
- 2022
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Ingår i: Clinical and Translational Neuroscience. - : MDPI AG. - 2514-183X. ; 6:2
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Tidskriftsartikel (refereegranskat)abstract
- Background: Laser-evoked potentials (LEPs) constitute an objective clinical diagnostic method used to investigate the functioning of the nociceptor system, including signaling in thin peripheral nerve fibers: Aδ and C fibers. There is preliminary evidence that phase locking LEPs with the breathing cycle can improve the parameters used to evaluate LEPs. Methods: We tested a simple breathing protocol as a low-cost improvement to LEP testing of the hands. Twenty healthy participants all underwent three variants of LEP protocols: following a video-guided twelve-second breathing instruction, watching a nature video, or using the classic LEP method of focusing on the hand being stimulated. Results: The breath protocol produced significantly shorter latencies as compared with the nature or classic protocol. It was also the least prone to artifacts and was deemed most acceptable by the subjects. There was no difference between the protocols regarding LEP amplitudes. Conclusions: Using a breathing video can be a simple, low-cost improvement for LEP testing in research and clinical diagnostics.
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