| 1. |
- Candefjord, Stefan, 1981, et al.
(författare)
-
A wearable microwave instrument can detect and monitor traumatic abdominal injuries in a porcine model
- 2021
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Abdominal injury is a frequent cause of death for trauma patients, and early recognition is essential to limit fatalities. There is a need for a wearable sensor system for prehospital settings that can detect and monitor bleeding in the abdomen (hemoperitoneum). This study evaluates the potential for microwave technology to fill that gap. A simple prototype of a wearable microwave sensor was constructed using eight antennas. A realistic porcine model of hemoperitoneum was developed using anesthetized pigs. Ten animals were measured at healthy state and at two sizes of bleeding. Statistical tests and a machine learning method were used to evaluate blood detection sensitivity. All subjects presented similar changes due to accumulation of blood, which dampened the microwave signal (p< 0.05). The machine learning analysis yielded an area under the receiver operating characteristic (ROC) curve (AUC) of 0.93, showing 100% sensitivity at 90% specificity. Large inter-individual variability of the healthy state signal complicated differentiation of bleedings from healthy state. A wearable microwave instrument has potential for accurate detection and monitoring of hemoperitoneum, with automated analysis making the instrument easy-to-use. Future hardware development is necessary to suppress measurement system variability and enable detection of smaller bleedings.
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| 2. |
- Candefjord, Stefan, 1981, et al.
(författare)
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Microwave technology for detecting traumatic intracranial bleedings: tests on phantom of subdural hematoma and numerical simulations
- 2017
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Ingår i: Medical and Biological Engineering and Computing. - : Springer Science and Business Media LLC. - 1741-0444 .- 0140-0118. ; 55:8, s. 1177-1188
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Tidskriftsartikel (refereegranskat)abstract
- Traumatic brain injury is the leading cause of death and severe disability for young people and a major public health problem for elderly. Many patients with intracranial bleeding are treated too late, because they initially show no symptoms of severe injury and are not transported to a trauma center. There is a need for a method to detect intracranial bleedings in the prehospital setting. In this study, we investigate whether broadband microwave technology (MWT) in conjunction with a diagnostic algorithm can detect subdural hematoma (SDH). A human cranium phantom and numerical simulations of SDH are used. Four phantoms with SDH 0, 40, 70 and 110 mL are measured with a MWT instrument. The simulated dataset consists of 1500 observations. Classification accuracy is assessed using fivefold cross-validation, and a validation dataset never used for training. The total accuracy is 100 and 82–96 % for phantom measurements and simulated data, respectively. Sensitivity and specificity for bleeding detection were 100 and 96 %, respectively, for the simulated data. SDH of different sizes is differentiated. The classifier requires training dataset size in order of 150 observations per class to achieve high accuracy. We conclude that the results indicate that MWT can detect and estimate the size of SDH. This is promising for developing MWT to be used for prehospital diagnosis of intracranial bleedings.
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| 3. |
- Fhager, Andreas, 1976, et al.
(författare)
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3D Simulations of Intracerebral Hemorrhage Detection Using Broadband Microwave Technology
- 2019
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Ingår i: Sensors. - : MDPI AG. - 1424-8220. ; 19:16
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Tidskriftsartikel (refereegranskat)abstract
- Early, preferably prehospital, detection of intracranial bleeding after trauma or stroke would dramatically improve the acute care of these large patient groups. In this paper, we use simulated microwave transmission data to investigate the performance of a machine learning classification algorithm based on subspace distances for the detection of intracranial bleeding. A computational model, consisting of realistic human head models of patients with bleeding, as well as healthy subjects, was inserted in an antenna array model. The Finite-Difference Time-Domain (FDTD) method was then used to generate simulated transmission coefficients between all possible combinations of antenna pairs. These transmission data were used both to train and evaluate the performance of the classification algorithm and to investigate its ability to distinguish patients with versus without intracranial bleeding. We studied how classification results were affected by the number of healthy subjects and patients used to train the algorithm, and in particular, we were interested in investigating how many samples were needed in the training dataset to obtain classification results better than chance. Our results indicated that at least 200 subjects, i.e., 100 each of the healthy subjects and bleeding patients, were needed to obtain classification results consistently better than chance (p < 0.05 using Student's t-test). The results also showed that classification results improved with the number of subjects in the training data. With a sample size that approached 1000 subjects, classifications results characterized as area under the receiver operating curve (AUC) approached 1.0, indicating very high sensitivity and specificity.
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| 4. |
- Fhager, Andreas, 1976, et al.
(författare)
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Microwave Diagnostics Ahead: Saving Time and the Lives of Trauma and Stroke Patients
- 2018
-
Ingår i: IEEE Microwave Magazine. - 1527-3342 .- 1557-9581. ; 19:3, s. 78-90
-
Tidskriftsartikel (refereegranskat)abstract
- Microwave technology has the potential to revolutionize how, when, and what care can be delivered to patients with acute, life-threatening medical conditions. The prospects are that microwave systems can both improve diagnostic ability and accuracy and enable earlier diagnosis. Early diagnosis is a key factor in acute situations, especially when breathing and circulation are affected. Conventional imaging modalities used for diagnostics, such as magnetic resonance imaging (MRI) and X-ray computed tomography (CT), are powerful but normally available only at hospitals.
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| 5. |
- Fhager, Andreas, 1976, et al.
(författare)
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Microwave Technology in Medical Diagnostics and Treatment
- 2015
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Ingår i: 2015 Ieee Mtt-S International Microwave Workshop Series on Rf and Wireless Technologies for Biomedical and Healthcare Applications. - New York : Ieee. - 9781479985432 ; , s. 133-134
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- There is a great need for novel diagnostics and treatment tools in today's healthcare. In this paper we describe our development and progress in novel microwave based diagnostics and treatment applications. The target applications are stroke diagnostics, breast cancer detection and microwave hyperthermia.
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| 6. |
- Kalm, Marie, 1981, et al.
(författare)
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Neurochemical Evidence of Potential Neurotoxicity After Prophylactic Cranial Irradiation.
- 2014
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Ingår i: International journal of radiation oncology, biology, physics. - : Elsevier BV. - 1879-355X .- 0360-3016. ; 89:3, s. 607-614
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Tidskriftsartikel (refereegranskat)abstract
- Toexamine whether cerebrospinal fluid biomarkers for neuroaxonal damage, neuroglial activation, and amyloid β-related processes could characterize the neurochemical response to cranial radiation.
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| 7. |
- Krogstad, Anne-Lene, 1956, et al.
(författare)
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Evaluation of objective methods to diagnose palmar hyperhidrosis and monitor effects of botulinum toxin treatment.
- 2004
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Ingår i: Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology. - : Elsevier BV. - 1388-2457. ; 115:8, s. 1909-16
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To evaluate (1) if laboratory tests may be a useful complement in diagnosing palmar hyperhidrosis and (2) if such tests can be used in the follow up examination of treatment effects. METHODS: Repeated measurements of evaporation and conductance were made in glabrous skin on hands and compared with subjective estimates of the degree of sweating in 20 control subjects and 20 patients with a history of palmar hyperhidrosis. In addition, 17 patients were monitored for up to 6 months after treatment of the hands with botulinum toxin A. RESULTS: Before treatment, evaporation in the palms was higher in the patients than in the control subjects but skin conductance did not differ between the groups. After treatment both evaporation and skin conductance decreased markedly in the patients and then slowly returned towards pretreatment values. CONCLUSIONS: Measurements of evaporation, but not skin conductance, may be a useful objective adjunct when diagnosing palmar hyperhidrosis. Both methods can, however, be used to monitor intraindividual changes of sweating over time.
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| 8. |
- Lambert, G., et al.
(författare)
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Acute response to intracisternal bupivacaine in patients with refractory pain of the head and neck
- 2006
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Ingår i: J Physiol. - : Wiley. - 0022-3751. ; 570:Pt 2, s. 421-8:570.2, s. 421-428
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Tidskriftsartikel (refereegranskat)abstract
- Continuous intracisternal infusion of bupivacaine for the management of intractable pain of the head and neck is effective in controlling pain in this patient group. With the catheter tip being located at the height of the C1 vertebral body, autonomic regulatory information may also be influenced by the infusion of bupivacaine. By combining direct sampling of cerebrospinal fluid (CSF), via a percutaneously placed catheter in the cisterna magna, with a noradrenaline and adrenaline isotope dilution method for examining sympathetic and adrenal medullary activity, we were able to quantify the release of brain neurotransmitters and examine efferent sympathetic nervous outflow in patients following intracisternal administration of bupivacaine. Despite severe pain, sympathetic and adrenal medullary activities were well within normal range (4.2 +/- 0.6 and 0.7 +/- 0.2 nmol min(-1), respectively, mean +/-S.E.M.). Intracisternal bupivacaine administration caused an almost instantaneous elevation in mean arterial blood pressure, increasing by 17 +/- 7 mmHg after 10 min (P < 0.01). Heart rate increased in parallel (17 +/- 5 beats min(-1)), and these changes coincided with an increase in sympathetic nervous activity, peaking with an approximately 50% increase over resting level 10 min after injection (P < 0.01). CSF levels of GABA were reduced following bupivacaine (P < 0.05). CSF catecholamines and serotonin, and EEG, remained unaffected. These results show that acutely administered bupivacaine in the cisterna magna of chronic pain sufferers leads to an activation of the sympathetic nervous system. The results suggest that the haemodynamic consequences occur as a result of interference with the neuronal circuitry in the brainstem. Although these effects are transient, they warrant caution at the induction of intracisternal local anaesthesia.
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| 9. |
- Oveland, Nils Petter, et al.
(författare)
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A wearable microwave detector for diagnosing thoracic injuries-test on a porcine pneumothorax model
- 2015
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Ingår i: Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine. - 1757-7241. ; 23:2
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- In the prehospital setting, a point-of-care diagnostic test is needed to diagnose pneumothorax (PTX) and monitor its progression to prevent unnecessary patient morbidity and mortality. Ultrasonography is more sensitive than supine chest x-ray for diagnosing PTX, but the accuracy depends on the experience of the operator. Therefore, a non-operator dependent instrument would be valuable for detection and continuous monitoring of an evolving PTX.
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| 10. |
- 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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| 11. |
- Persson, Mikael, 1959, et al.
(författare)
-
Microwave based diagnostics and treatment in practice
- 2013
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Ingår i: 2013 IEEE MTT-S International Microwave Workshop Series on RF and Wireless Technologies for Biomedical and Healthcare Applications, IMWS-BIO 2013 - Proceedings.
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Konferensbidrag (refereegranskat)abstract
- Globally, around 15 million people each year suffer a stroke. Only a small fraction of stroke patients who could benefit from thrombolytic treatment reach diagnosis and treatment in time. To increase this low figure we have developed microwave technology aiming to differentiate hemorrhagic from ischemic stroke patients. The standard method for breast cancer diagnosis today is X-ray mammography. Despite its recognized ability to detect tumors it suffers from some limitations. Neither the false positive nor the false negative detection rates are negligible. An interesting alternative being researched extensively today is microwave tomography. In our current strive to develop a clinical prototype we have found that the most suitable design consists of an antenna array placed in a full 3D pattern. During the last decade clinical studies have demonstrated the ability of microwave hyperthermia to dramatically enhance cancer patient survival. The fundamental challenge is to adequately heat deep-seated tumors while preventing surrounding healthy tissue from undesired heating and damage. We are specifically addressing the challenge to deliver power levels with spatial control, patient treatment planning, and noninvasive temperature measurements. © 2013 IEEE.
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| 12. |
- Persson, Mikael, 1959, et al.
(författare)
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Microwave-Based Stroke Diagnosis Making Global Prehospital Thrombolytic Treatment Possible
- 2014
-
Ingår i: IEEE Transactions on Biomedical Engineering. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9294 .- 1558-2531. ; 61:11, s. 2806-2817
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Tidskriftsartikel (refereegranskat)abstract
- Here, we present two different brain diagnostic devices based on microwave technology and the associated two first proof-of-principle measurements that show that the systems can differentiate hemorrhagic from ischemic stroke in acute stroke patients, as well as differentiate hemorrhagic patients from healthy volunteers. The system was based on microwave scattering measurements with an antenna system worn on the head. Measurement data were analyzed with a machine-learning algorithm that is based on training using data from patients with a known condition. Computer tomography images were used as reference. The detection methodology was evaluated with the leave-one-out validation method combined with a Monte Carlo-based bootstrap step. The clinical motivation for this project is that ischemic stroke patients may receive acute thrombolytic treatment at hospitals, dramatically reducing or abolishing symptoms. A microwave system is suitable for prehospital use, and therefore has the potential to allow significantly earlier diagnosis and treatment than today.
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| 13. |
- Persson, Mikael, 1959, et al.
(författare)
-
Pre-hospital care for stroke and trauma
- 2015
-
Ingår i: Conference Proceedings, 2014 IEEE MTT-S International Microwave Workshop Series on: RF and Wireless Technologies for Biomedical and Healthcare Applications, IMWS-Bio 2014, London, United Kingdom, 8-10 December 2014. - 9781479954476
-
Konferensbidrag (refereegranskat)abstract
- Pre-hospital care for stroke and trauma remains one of the global challenges., Each year around 15 million people each year suffer a stroke. Only a small fraction of stroke patients who could benefit from thrombolytic treatment reach diagnosis and treatment in time. To increase this low figure we have developed microwave technology aiming to differentiate hemorrhagic from ischemic stroke patients in a pre-hospital setting.
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| 14. |
- Brown, Rachael, et al.
(författare)
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Assessing the integrity of sympathetic pathways in spinal cord injury.
- 2007
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Ingår i: Autonomic neuroscience : basic & clinical. - : Elsevier BV. - 1566-0702. ; 134:1-2, s. 61-8
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Tidskriftsartikel (refereegranskat)abstract
- STUDY DESIGN: Measurement of cutaneous sympathetic reflexes and hemodynamic responses to brief electrical stimuli applied above (forehead) and below (abdominal wall) a spinal lesion. OBJECTIVE: To assess the validity of using cutaneous vasoconstriction as a sensitive indicator of increases in sympathetic activity in spinal cord injury. SETTING: Prince of Wales Medical Research Institute, Australia. SUBJECTS: Twenty spinal cord injured subjects with injuries ranging from C3-T11 and nine able-bodied controls. METHOD: Cutaneous electrical stimulation was applied to the forehead and abdominal wall to subjects at unexpected times. Sudomotor and vasomotor responses, as well as continuous arterial pressure, heart rate and respiration were monitored. RESULTS: Sudomotor (electrodermal) responses to forehead stimulation were scarce in spinal cord injured subjects, whereas cutaneous vasoconstrictor responses (photoelectric pulse plethysmography) provided a sensitive indicator of any remaining central control of sympathetic function below the lesion. Electrical stimulation applied to the abdominal wall evoked vasoconstrictor reflexes below the lesion in the majority of spinal cord injured subjects, whereas only a limited number of electrodermal responses were observed. That these cutaneous vasoconstrictor responses could reflect parallel increases in muscle and splanchnic vasoconstrictor activity was indicated by the increases in blood pressure; patients lacking vasoconstrictor responses rarely showed stimulus-induced blood pressure increases. CONCLUSION: Our findings show that skin vasomotor responses to somatosensory stimulation provide a more sensitive tool than electrodermal responses for evaluation of sympathetic function below a spinal cord lesion. STATEMENT OF ETHICS: We certify that all applicable institutional and governmental regulations concerning the ethical use of human volunteers were followed during the course of this research, and all experiments were conducted with the understanding and consent of each subject.
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| 15. |
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| 16. |
- Donadio, Vincenzo, et al.
(författare)
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Anhidrosis in multiple system atrophy: a preganglionic sudomotor dysfunction?
- 2008
-
Ingår i: Movement disorders : official journal of the Movement Disorder Society. - : Wiley. - 1531-8257. ; 23:6, s. 885-8
-
Tidskriftsartikel (refereegranskat)abstract
- Anhidrosis occurs in the majority of multiple system atrophy (MSA) patients but the underlying site of lesion is not well established. We describe three patients with long-standing MSA and anhidrosis diagnosed on the basis of a thermoregulatory sweating test. In biopsies of anhidrotic skin, immunofluorescence analysis disclosed a well preserved postganglionic sudomotor innervation in all three patients supporting the hypothesis of a preganglionic nerve fiber lesion underlying their anhidrosis. Postganglionic sudomotor fiber integrity was also confirmed by normal electrodermal responses in one patient, whereas such responses and microneurographically detectable skin sympathetic nerve activity were absent in the other two MSA patients, suggesting a functional inactivity of structurally intact postganglionic sympathetic skin fibers.
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| 17. |
- Donadio, Vincenzo, et al.
(författare)
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Arousal elicits exaggerated inhibition of sympathetic nerve activity in phobic syncope patients.
- 2007
-
Ingår i: Brain : a journal of neurology. - : Oxford University Press (OUP). - 1460-2156. ; 130:Pt 6, s. 1653-62
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Tidskriftsartikel (refereegranskat)abstract
- Alerting stimuli causing arousal have been shown to elicit a reproducible transient inhibition of muscle sympathetic nerve activity (MSNA) in healthy subjects. The aim of the present study was to test whether this inhibitory response to arousal is exaggerated in patients with a history of vasovagal syncope. We studied 24 untreated syncope patients, 12 of whom met the DSM-IV-TR diagnostic criteria for blood/injury phobia and 18 age-matched healthy subjects. MSNA was recorded from the peroneal nerve at the fibular head. Arousal was induced by randomly presented trains of five electrical pulses delivered to a finger. The pulses were triggered on five consecutive R waves of the ECG, with a delay of 200 ms. Patients also underwent cardiological and neurological examinations, tilt test and a structured interview to investigate diagnostic criteria for specific phobia. The syncope patients had significantly lower resting MSNA (29 +/- 2 bursts/min) and diastolic blood pressure (BP, 78 +/- 2 mmHg) compared to controls (36 +/- 2 bursts/min and 84 +/- 3 mmHg; P < 0.05), whereas no significant differences were found for resting heart rate and systolic BP. The phobic patient group exhibited prolonged sympathetic inhibitions to arousal stimuli compared to controls and non-phobic patients, whereas no difference was found between tilt-positive and tilt-negative patients or between controls and non-phobic patients. The findings suggest that the degree of inhibition in response to arousal stimuli is related to a subjective factor coupled to fear of blood/injury. The exaggerated inhibition in patients with phobia to blood/injury may be a factor predisposing to syncope in those patients.
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| 18. |
- Donadio, Vincenzo, et al.
(författare)
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Daytime sympathetic hyperactivity in OSAS is related to excessive daytime sleepiness.
- 2007
-
Ingår i: Journal of sleep research. - : Wiley. - 0962-1105 .- 1365-2869. ; 16:3, s. 327-32
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate the relationships among sympathetic hyperactivity, excessive daytime sleepiness (EDS) and hypertension in obstructive sleep apnoea syndrome (OSAS). Ten newly diagnosed OSAS patients with untreated EDS and daytime hypertension underwent polysomnography (PSG) and daytime measurements of plasma noradrenaline (NA), ambulatory blood pressure (BP), muscle sympathetic nerve activity (MSNA) by microneurography and objective assessment of EDS before and during 6 months of compliance-monitored continuous positive airway pressure (CPAP) treatment. One month after the start of CPAP, BP, MSNA and NA were significantly lowered, remaining lower than baseline also after 3 and 6 months of treatment. CPAP use caused a significant improvement of sleep structures, and reduced EDS. A statistical correlation analysis demonstrated that EDS was not correlated with sleep measures obtained from baseline PSG (% sleep stages, apnoea and arousal index, mean oxygen saturation value), whereas daytime sleepiness was significantly correlated with MSNA. Furthermore, MSNA and BP showed no correlation. Our data obtained from selected patients suggest that the mechanisms inducing EDS in OSAS are related to the degree of daytime sympathetic hyperactivity. Additionally, resting MSNA was unrelated to BP suggesting that factors other than adrenergic neural tone make a major contribution to OSAS-related hypertension. The results obtained in this pilot study need, however, to be confirmed in a larger study involving more patients.
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| 19. |
- Donadio, V., et al.
(författare)
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Muscle sympathetic response to arousal predicts neurovascular reactivity during mental stress
- 2012
-
Ingår i: Journal of Physiology-London. - : Wiley. - 0022-3751. ; 590:12, s. 2885-2896
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Tidskriftsartikel (refereegranskat)abstract
- Key points Mental stress (MS) is often initiated by a sensory or cognitive stimulus, which induces a brief arousal reaction followed by a longer stress phase. Both phases induce blood pressure (BP) increases whereas effects on muscle sympathetic nerve activity (MSNA) vary: in approximately 50% of healthy subjects (responders) arousal induces a brief MSNA reduction, which is absent in the remaining 50% (non-responders). We now report a link between the arousal response and neurovascular effects of MS in healthy males. Our data show that during MS, responders to arousal exhibited a significant decrease of MSNA and a lesser BP increase compared to non-responders. The whole material displayed a positive correlation between MSNA responses induced by arousal and MS. In addition, arousal induced MSNA changes correlated positively with BP changes during MS. We conclude that the MSNA response to arousal predicts MSNA and BP responses to MS.
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| 20. |
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| 21. |
- Eder, Derek, 1959, et al.
(författare)
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Sympathetic nerve and cardiovascular responses to auditory startle and prepulse inhibition.
- 2009
-
Ingår i: International Journal of Psychophysiology. - : Elsevier BV. - 0167-8760. ; 71:2, s. 149-155
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Tidskriftsartikel (refereegranskat)abstract
- While sudden (startling) sensory stimuli are generally thought of as inducing sympathetic excitation, in humans there is a short-lasting inhibition of limb muscle sympathetic nerve activity (MSNA). This study is the first to examine and contrast the effects of acoustic startle and the prepulse inhibition of startle (PPI) on MSNA, blood pressure, heart rate, and eye blinks. Startle elicited a two-component withdrawal of MSNA: an early inhibition of one sympathetic burst followed by a second inhibition. PPI abolished the early, but not the late MSNA inhibition. Prepulse stimuli alone had no early inhibitory effects on MSNA. Early MSNA inhibition, which may occur at latencies of approximately 100 ms, appears to be part of a CNS-generated startle reflex which subserves automatic defensive responses to potential threats. The late MSNA inhibition coincided with the stimulus-induced blood pressure increase and is probably an inhibitory reflex response.
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| 22. |
- El-Merhi, Ali, et al.
(författare)
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Towards Trustworthy Cross-patient Model Development
- 2021
-
Ingår i: ArXiv:2112.1044.
-
Konferensbidrag (refereegranskat)abstract
- Machine learning is used in medicine to support physicians in examination, diagnosis, and predicting outcomes. One of the most dynamic area is the usage of patient generated health data from intensive care units. The goal of this paper is to demonstrate how we advance cross-patient ML model development by combining the patient’s demographics data with their physiological data. We used a population of patients undergoing Carotid Enderarterectomy (CEA), where we studied differences in model performance and explainability when trained for all patients and one patient at a time. The results show that patients’ demographics has a large impact on the performance and explainability and thus trustworthiness. We conclude that we can increase trust in ML models in a cross-patient context, by careful selection of models and patients based on their demographics and the surgical procedure.
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| 23. |
- El-Merhi, Ali, et al.
(författare)
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Trusting Machine Learning Results from Medical Procedures in the Operating Room
- 2022
-
Ingår i: ArXiv 2022.
-
Konferensbidrag (refereegranskat)abstract
- Machine learning can be used to analyse physiological data for several purposes. Detection of cerebral ischemia is an achievement that would have high impact on patient care. We attempted to study if collection of continous physiological data from non-invasive monitors, and analysis with machine learning could detect cerebral ischemia in tho different setting, during surgery for carotid endarterectomy and during endovascular thrombectomy in acute stroke. We compare the results from the two different group and one patient from each group in details. While results from CEA-patients are consistent, those from thrombectomy patients are not and frequently contain extreme values such as 1.0 in accuracy. We conlcude that this is a result of short duration of the procedure and abundance of data with bad quality resulting in small data sets. These results can therefore not be trusted.
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| 24. |
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| 25. |
- Fhager, A., et al.
(författare)
-
Microwave Diagnostics Ahead
- 2018
-
Ingår i: Ieee Microwave Magazine. - : Institute of Electrical and Electronics Engineers (IEEE). - 1527-3342. ; 19:3, s. 78-90
-
Tidskriftsartikel (refereegranskat)abstract
- Microwave technology has the potential to revolutionize how, when, and what care can be delivered to patients with acute, life-threatening medical conditions. The prospects are that microwave systems can both improve diagnostic ability and accuracy and enable earlier diagnosis. Early diagnosis is a key factor in acute situations, especially when breathing and circulation are affected. Conventional imaging modalities used for diagnostics, such as magnetic resonance imaging (MRI) and X-ray computed tomography (CT), are powerful but normally available only at hospitals.
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| 26. |
- Gerster, S., et al.
(författare)
-
Testing a linear time invariant model for skin conductance responses by intraneural recording and stimulation
- 2018
-
Ingår i: Psychophysiology. - : Wiley. - 0048-5772 .- 1469-8986. ; 55:2
-
Tidskriftsartikel (refereegranskat)abstract
- Skin conductance responses (SCR) are increasingly analyzed with model-based approaches that assume a linear and time-invariant (LTI) mapping from sudomotor nerve (SN) activity to observed SCR. These LTI assumptions have previously been validated indirectly, by quantifying how much variance in SCR elicited by sensory stimulation is explained under an LTI model. This approach, however, collapses sources of variability in the nervous and effector organ systems. Here, we directly focus on the SN/SCR mapping by harnessing two invasive methods. In an intraneural recording experiment, we simultaneously track SN activity and SCR. This allows assessing the SN/SCR relationship but possibly suffers from interfering activity of non-SN sympathetic fibers. In an intraneural stimulation experiment under regional anesthesia, such influences are removed. In this stimulation experiment, about 95% of SCR variance is explained under LTI assumptions when stimulation frequency is below 0.6 Hz. At higher frequencies, nonlinearities occur. In the intraneural recording experiment, explained SCR variance is lower, possibly indicating interference from non-SN fibers, but higher than in our previous indirect tests. We conclude that LTI systems may not only be a useful approximation but in fact a rather accurate description of biophysical reality in the SN/SCR system, under conditions of low baseline activity and sporadic external stimuli. Intraneural stimulation under regional anesthesia is the most sensitive method to address this question. © 2017 The Authors. Psychophysiology published by Wiley Periodicals, Inc. on behalf of Society for Psychophysiological Research
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| 27. |
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| 28. |
- Jonsson Eskelin, John, 1987, et al.
(författare)
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From MEG to clinical EEG: evaluating a promising non-invasive estimator of defense-related muscle sympathetic nerve inhibition
- 2023
-
Ingår i: Scientific Reports. - 2045-2322. ; 13:1
-
Tidskriftsartikel (refereegranskat)abstract
- Sudden, unexpected stimuli can induce a transient inhibition of sympathetic vasoconstriction to skeletal muscle, indicating a link to defense reactions. This phenomenon is relatively stable within, but differs between, individuals. It correlates with blood pressure reactivity which is associated with cardiovascular risk. Inhibition of muscle sympathetic nerve activity (MSNA) is currently characterized through invasive microneurography in peripheral nerves. We recently reported that brain neural oscillatory power in the beta spectrum (beta rebound) recorded with magnetoencephalography (MEG) correlated closely with stimulus-induced MSNA inhibition. Aiming for a clinically more available surrogate variable reflecting MSNA inhibition, we investigated whether a similar approach with electroencephalography (EEG) can accurately gauge stimulus-induced beta rebound. We found that beta rebound shows similar tendencies to correlate with MSNA inhibition, but these EEG data lack the robustness of previous MEG results, although a correlation in the low beta band (13-20 Hz) to MSNA inhibition was found (p = 0.021). The predictive power is summarized in a receiver-operating-characteristics curve. The optimum threshold yielded sensitivity and false-positive rate of 0.74 and 0.33 respectively. A plausible confounder is myogenic noise. A more complicated experimental and/or analysis approach is required for differentiating MSNA-inhibitors from non-inhibitors based on EEG, as compared to MEG.
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| 29. |
- Kenet, T., et al.
(författare)
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Disconnectivity of the cortical ocular motor control network in autism spectrum disorders
- 2012
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Ingår i: Neuroimage. - : Elsevier BV. - 1053-8119. ; 61:4, s. 1226-1234
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Tidskriftsartikel (refereegranskat)abstract
- Response inhibition, or the suppression of prepotent but contextually inappropriate behaviors, is essential to adaptive, flexible responding. Individuals with autism spectrum disorders (ASD) consistently show deficient response inhibition during antisaccades. In our prior functional MRI study, impaired antisaccade performance was accompanied by reduced functional connectivity between the frontal eye field (FEF) and dorsal anterior cingulate cortex (dACC), regions critical to volitional ocular motor control. Here we employed magnetoencephalography (MEG) to examine the spectral characteristics of this reduced connectivity. We focused on coherence between FEF and dACC during the preparatory period of antisaccade and prosaccade trials, which occurs after the presentation of the task cue and before the imperative stimulus. We found significant group differences in alpha band mediated coherence. Specifically, neurotypical participants showed significant alpha band coherence between the right inferior FEF and right dACC and between the left superior FEF and bilateral dACC across antisaccade, prosaccade, and fixation conditions. Relative to the neurotypical group, ASD participants showed reduced coherence between these regions in all three conditions. Moreover, while neurotypical participants showed increased coherence between the right inferior FEF and the right dACC in preparation for an antisaccade compared to a prosaccade or fixation, ASD participants failed to show a similar increase in preparation for the more demanding antisaccade. These findings demonstrate reduced long-range functional connectivity in ASD, specifically in the alpha band. The failure in the ASD group to increase alpha band coherence with increasing task demand may reflect deficient top-down recruitment of additional neural resources in preparation to perform a difficult task. (C) 2012 Elsevier Inc. All rights reserved.
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| 30. |
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| 31. |
- Krämer, Heidrun H, et al.
(författare)
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Central correlation of muscle sympathetic nerve activation during baroreflex unloading - a microneurography-positron emission tomography study
- 2014
-
Ingår i: European Journal of Neuroscience. - : Wiley. - 0953-816X .- 1460-9568. ; 39:4, s. 623-629
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Tidskriftsartikel (refereegranskat)abstract
- The baroreceptor reflex controls spontaneous fluctuations in blood pressure. One major control variable of the baroreflex is the sympathetic vasoconstrictor activity to muscles [MSNA; burst frequency (BF) and burst incidence (BI)], which can be quantitatively assessed by microneurography. We aimed to investigate the central regions involved in baroreflex regulation of MSNA. Healthy men (mean age 25 years) participated in three experimental sessions. (i) Microneurography recordings of MSNA from the left peroneal nerve during rest and baroreflex unloading, induced by lower body negative pressure (LBNP; -40 mmHg). If MSNA could be reliably recorded throughout this procedure (n = 15), the subjects entered the positron emission tomography (PET) experiments. The two PET sessions took place in a randomised order. Cerebral glucose metabolism (18-fluorodeoxyglucose) was analysed after: (ii) baroreflex unloading (LBNP); and (iii) control condition (lying in the LBNP chamber without suction). The PET data were analysed employing SPM8. LBNP elicited a significant increase in MSNA in all successfully recorded subjects (BI: P = 0.001; F = 5.54; BF: P < 0.001; F = 36.59). As compared with the control condition, LBNP was associated with increased PET regional glucose metabolism bilaterally in the orbitofrontal cortex (OFC; BA 11, 47). Related to the rise of BF, there was increased activation of the left OFC (BA 11); related to the rise of BI there was increased activation of the brainstem corresponding to the rostral ventrolateral medulla. Our data support a role for the ventrolateral medulla and the OFC in baroreflex-mediated control of MSNA in humans. © 2013 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.
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| 32. |
- Lambert, Elisabeth A, et al.
(författare)
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Single-unit muscle sympathetic nervous activity and its relation to cardiac noradrenaline spillover.
- 2011
-
Ingår i: The Journal of physiology. - : Wiley. - 1469-7793 .- 0022-3751. ; 589:Pt 10, s. 2597-605
-
Tidskriftsartikel (refereegranskat)abstract
- Recent work using single-unit sympathetic nerve recording techniques has demonstrated aberrations in the firing pattern of sympathetic nerves in a variety of patient groups. We sought to examine whether nerve firing pattern is associated with increased noradrenaline release. Using single-unit muscle sympathetic nerve recording techniques coupled with direct cardiac catheterisation and noradrenaline isotope dilution methodology we examined the relationship between single-unit firing patterns and cardiac and whole body noradrenaline spillover to plasma. Participants comprised patients with hypertension (n=6), depression (n=7) and panic disorder (n =9) who were drawn from our ongoing studies. The patient groups examined did not differ in their single-unit muscle sympathetic nerve firing characteristics nor in the rate of spillover of noradrenaline to plasma from the heart. The median incidence of multiple spikes per beat was 9%. Patients were stratified according to the firing pattern: low level of incidence (less than 9% incidence of multiple spikes per beat) and high level of incidence (greater than 9% incidence of multiple spikes per beat). High incidence of multiple spikes within a cardiac cycle was associated with higher firing rates (P <0.0001) and increased probability of firing (P <0.0001). Whole body noradrenaline spillover to plasma and (multi-unit) muscle sympathetic nerve activity in subjects with low incidence of multiple spikes was not different to that of those with high incidence of multiple spikes. In those with high incidence of multiple spikes there occurred a parallel activation of the sympathetic outflow to the heart, with cardiac noradrenaline spillover to plasma being two times that of subjects with low nerve firing rates (11.0 ± 1.5 vs. 22.0 ± 4.5 ng min⁻¹, P <0.05). This study indicates that multiple within-burst firing and increased single-unit firing rates of the sympathetic outflow to the skeletal muscle vasculature is associated with high cardiac noradrenaline spillover.
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| 33. |
- Lautenschlager, G., et al.
(författare)
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The impact of baroreflex function on endogenous pain control: a microneurography study
- 2015
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Ingår i: European Journal of Neuroscience. - : Wiley. - 0953-816X. ; 42:11, s. 2996-3003
-
Tidskriftsartikel (refereegranskat)abstract
- The interaction between sympathetic vasoconstrictor activity to muscles [muscle sympathetic nerve activity (MSNA), burst frequency (BF) and burst incidence (BI)] and different stress and somatosensory stimuli is still unclear. Eighteen healthy men (median age 28 years) underwent microneurography recordings from the peroneal nerve. MSNA was recorded during heat pain (HP) and cold pain (CP) alone as well as combined with different stress tasks (mental arithmetic, singing, giving a speech). An additional nine healthy men (median age 26 years) underwent the stimulation protocol with an additional control task (thermal pain combined with listening to music) to evaluate possible attentional confounders. MSNA was significantly increased by CP and HP. CP-evoked responses were smaller. The diastolic blood pressure followed the time course of MSNA while heart rate remained unchanged. The mental stress tasks further increased MSNA and were sufficient to reduce pain while the control task had no effect. MSNA activity correlated negatively with pain intensity and positively with analgesia. High blood pressure values were associated with lower pain intensity. Our study indicates an impact of central sympathetic drive on pain and pain control.
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| 34. |
- Lin, Cindy Shin-Yi, et al.
(författare)
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Axonal changes in spinal cord injured patients distal to the site of injury.
- 2007
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Ingår i: Brain : a journal of neurology. - : Oxford University Press (OUP). - 1460-2156. ; 130:Pt 4, s. 985-94
-
Tidskriftsartikel (refereegranskat)abstract
- It is generally assumed that the peripheral nervous system remains intact following a spinal injury. Accordingly, the electrical thresholds of motor axons in a peripheral nerve below the lesion should be similar to those in intact subjects. Yet in attempts to enter the common peroneal nerve with microelectrodes in 24 quadriplegic or paraplegic individuals it was often found that electrical stimulation over or within the nerve failed to elicit contractions in the pre-tibial flexors. To investigate whether consistent changes in axonal physiology occurred distal to the site of injury in patients with spinal cord injury (SCI), motor nerve excitability was formally tested in 15 of these patients. Threshold tracking techniques were used to measure axonal excitability parameters (stimulus-response curves, strength-duration properties, threshold electrotonus, a current-threshold relationship and the recovery cycle) of motor axons in the median and common peroneal nerves. In these patients motor axons were uniformly of high threshold and consequently, stimulus-response curves were shifted to the right. In some SCI patients, axons were completely inexcitable. Amplitudes of compound motor action potentials were reduced, consistent with axonal loss and strength-duration time constant was significantly reduced in SCI patients (SCI 0.13 +/- 0.02 ms, controls 0.43 +/- 0.02 ms, mean +/- SE, P < 0.0001). Excitability changes were more prominent the more clinically severe the injury, with progressive deterioration over time since the original injury. While compression and traction sustained during the original injury or subsequent hospital rehabilitation may contribute in part to some of these changes, it is difficult to attribute these findings solely to such processes. Changes in axonal structure and ion channel function, but perhaps more critically decentralization and consequent inactivity, are likely to underlie the complex changes observed in axonal excitability in SCI patients.
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| 35. |
- Linde, Mattias, 1966, et al.
(författare)
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Sumatriptan (5-HT1B/1D-agonist) causes a transient allodynia.
- 2004
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Ingår i: Cephalalgia : an international journal of headache. - : SAGE Publications. - 0333-1024. ; 24:12, s. 1057-66
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Tidskriftsartikel (refereegranskat)abstract
- Unpleasant sensory symptoms are commonly reported in association with the use of 5-HT1B/1D-agonists, i.e. triptans. In particular, pain/pressure symptoms from the chest and neck have restricted the use of triptans in the acute treatment of migraine. The cause of these triptan induced side-effects is still unidentified. We have now tested the hypothesis that sumatriptan influences the perception of tactile and thermal stimuli in humans in a randomized, double-blind, placebo-controlled cross-over study. Two groups were tested; one consisted of 12 (mean age 41.2 years, 10 women) subjects with migraine and a history of cutaneous allodynia in association with sumatriptan treatment. Twelve healthy subjects (mean age 38.7 years, 10 women) without migraine served as control group. During pain- and medication-free intervals tactile directional sensibility, perception of dynamic touch (brush) and thermal sensory and pain thresholds were studied on the dorsal side of the left hand. Measurements were performed before, 20, and 40 min after injection of 6 mg sumatriptan or saline. Twenty minutes after injection, sumatriptan caused a significant placebo-subtracted increase in brush-evoked feeling of unpleasantness in both groups (P < 0.01), an increase in brush-evoked pain in migraineurs only (P = 0.021), a reduction of heat pain threshold in all participants pooled (P = 0.031), and a reduction of cold pain threshold in controls only (P = 0.013). At 40 min after injection, no differences remained significant. There were no changes in ratings of brush intensity, tactile directional sensibility or cold or warm sensation thresholds. Thus, sumatriptan may cause a short-lasting allodynia in response to light dynamic touch and a reduction of heat and cold pain thresholds. This could explain at least some of the temporary sensory side-effects of triptans and warrants consideration in the interpretation of studies on migraine-induced allodynia.
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| 36. |
- Lundblad, Linda, et al.
(författare)
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Sympathetic Nerve Activity in Monozygotic Twins Identical at Rest but Not During Arousal
- 2017
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Ingår i: Hypertension. - : Ovid Technologies (Wolters Kluwer Health). - 0194-911X .- 1524-4563. ; 69:5, s. 964-969
-
Tidskriftsartikel (refereegranskat)abstract
- Microneurographic recordings of human muscle sympathetic nerve activity responses to sudden sensory stimuli (ie, arousal) have revealed 2 intraindividually reproducible response profiles in healthy young males that predict different neural and blood pressure responses to more sustained stress. Approximately 50% of subjects inhibit muscle sympathetic nerve activity during arousal, whereas the remaining 50% do not, and the latter group displays a markedly greater blood pressure increase in response to arousal, as well as during and after 3 minutes of mental arithmetic. Studying a group of monozygotic twins (10 pairs, 2 excluded from analysis), the aim of the present study was to evaluate the degree of genetic determination of these sympathetic response profiles. Muscle sympathetic burst incidence at rest was similar in twins, with a within-pair burst incidence ratio of 0.87 +/- 0.02 (SEM) compared with 0.73 +/- 0.07 found in unrelated pairs (P= 0.002), confirming a previous study from our laboratory. In contrast, the sympathetic responses to arousal showed large twin within-pair variance (arousal inhibition ratio 0.56 +/- 0.11), which did not significantly differ (P= 0.939) from the variance in pairs of unrelated subjects (0.46 +/- 0.11). The finding that human muscle sympathetic nerve responses to arousal are less determined by genotype than the resting level of corresponding sympathetic nerve activity suggests that the arousal response pattern is more prone to be altered by environmental factors. This raises the possibility that these intraindividually reproducible sympathetic neural response profiles can be modified in a positive direction from a cardiovascular risk perspective.
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| 37. |
- Löken, Line Sofie, 1977, et al.
(författare)
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Tactile direction discrimination and vibration detection in diabetic neuropathy.
- 2009
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Ingår i: Acta neurologica Scandinavica. - : Hindawi Limited. - 1600-0404 .- 0001-6314. ; 121:5, s. 302-308
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Tidskriftsartikel (refereegranskat)abstract
- Löken LS, Lundblad LC, Elam M, Olausson HW. Tactile direction discrimination and vibration detection in diabetic neuropathy. Acta Neurol Scand: DOI: 10.1111/j.1600-0404.2009.01282.x. (c) 2009 The Authors Journal compilation (c) 2009 Blackwell Munksgaard.Objective - To evaluate the clinical usefulness of quantitative testing of tactile direction discrimination (TDD) in patients with diabetic neuropathy. Materials and methods - TDD and vibration detection were examined on the dorsum of the feet in 43 patients with type 1 diabetes mellitus and clinical signs and symptoms indicating mild neuropathy, and abnormal results for neurography, temperature detection, or heart rate variability. Test-retest examination of TDD was performed in nine of the patients. Results - Twenty-six of the patients had abnormal TDD (sensitivity 0.60) and 20 had abnormal vibration detection (sensitivity 0.46). Ten of the patients had abnormal TDD and normal vibration detection. Four of the patients had abnormal vibration detection and normal TDD. Test-retest examination of TDD showed a high degree of reproducibility (r = 0.87). Conclusion - TDD seems more useful than vibration detection in examination of diabetic neuropathy.
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| 38. |
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| 39. |
- Macefield, Vaughan G, et al.
(författare)
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Firing properties of sudomotor neurones in hyperhidrosis and thermal sweating.
- 2008
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Ingår i: Clinical autonomic research : official journal of the Clinical Autonomic Research Society. - : Springer Science and Business Media LLC. - 0959-9851. ; 18:6, s. 325-30
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: Idiopathic palmar-plantar hyperhidrosis is characterized by excessive sweating of the palms and feet, and is commonly treated by transthoracic regional sympathicotomy. As the condition is believed to be due to a high sudomotor drive, we wanted to assess the firing properties of individual sudomotor neurones in this state of sympathoexcitation, extending our recent work on other pathologies associated with high sympathetic nerve activity. METHODS: Single-unit recordings were made from eight sudomotor neurones supplying the fingers via tungsten microelectrodes inserted percutaneously into the median nerve at the wrist or upper arm. RESULTS: Typical of sudomotor, muscle vasoconstrictor and cutaneous vasoconstrictor neurones recorded in healthy individuals in states of high sympathetic drive, all units had low firing probabilities (active in only 30.0 +/- 6.7 (SE) % of cardiac intervals) and primarily fired only once per heart beat. The percentage of cardiac intervals in which the neurones generated 1, 2, 3 or 4 spikes was 60.4 +/- 6.3, 22.9 +/- 3.9, 9.7 +/- 2.1 and 3.4 +/- 1.3%, respectively. For comparison, these values were 77.6 +/- 7.7, 15.0 +/- 4.1, 4.6 +/- 2.3 and 1.8 +/- 1.3% for eight sudomotor neurones innervating the hairy skin of the foot during thermally-induced sweating in normal subjects. INTERPRETATION: We conclude that the firing properties of spontaneously active sudomotor neurones in subjects with hyperhidrosis are similar to those of sudomotor neurones active during thermal sweating, reflecting an increase in central sympathetic drive to the sweat glands in hyperhidrosis.
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| 40. |
- Olausson, Håkan, 1965, et al.
(författare)
-
Functional role of unmyelinated tactile afferents in human hairy skin: sympathetic response and perceptual localization.
- 2008
-
Ingår i: Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale. - : Springer Science and Business Media LLC. - 1432-1106. ; 184:1, s. 135-40
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Tidskriftsartikel (refereegranskat)abstract
- In addition to A-beta fibres the human hairy skin has unmyelinated (C) fibres responsive to light touch. Previous functional magnetic resonance imaging (fMRI) studies in a subject with a neuronopathy who specifically lacks A-beta afferents indicated that tactile C afferents (CT) activate insular cortex, whereas no response was seen in somatosensory areas 1 and 2. Psychophysical tests suggested that CT afferents give rise to an inconsistent perception of weak and pleasant touch. By examining two neuronopathy subjects as well as control subjects we have now demonstrated that CT stimulation can elicit a sympathetic skin response. Further, the neuronopathy subjects' ability to localize stimuli which activate CT afferents was very poor but above chance level. The findings support the interpretation that the CT system is well suited to underpin affective rather than discriminative functions of tactile sensations.
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| 41. |
- Olausson, Håkan, 1965, et al.
(författare)
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Unmyelinated tactile afferents have opposite effects on insular and somatosensory cortical processing.
- 2008
-
Ingår i: Neuroscience letters. - : Elsevier BV. - 0304-3940. ; 436:2, s. 128-32
-
Tidskriftsartikel (refereegranskat)abstract
- A previous functional magnetic resonance imaging (fMRI) study of an A-beta deafferented subject (GL) showed that stimulation of tactile C afferents (CT) activates insular cortex whereas no activation was seen in somatosensory cortices. Psychophysical studies suggested that CT afferents contribute to affective but not to discriminative aspects of tactile stimulation. We have now examined cortical processing following CT stimulation in a second similarly deafferented subject (IW), as well as revisited the data from GL. The results in IW showed similar activation of posterior insular cortex following CT stimulation as in GL and so strengthen the view that CT afferents underpin emotional aspects of touch. In addition, CT stimulation evoked significant fMRI deactivation in somatosensory cortex in both subjects supporting the notion that CT is not a system for discriminative touch.
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| 42. |
- Orekhova, Elena V, 1967, et al.
(författare)
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Auditory Cortex Responses to Clicks and Sensory Modulation Difficulties in Children with Autism Spectrum Disorders (ASD)
- 2012
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Ingår i: Plos One. - : Public Library of Science (PLoS). - 1932-6203. ; 7:6
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Tidskriftsartikel (refereegranskat)abstract
- Auditory sensory modulation difficulties are common in autism spectrum disorders (ASD) and may stem from a faulty arousal system that compromises the ability to regulate an optimal response. To study neurophysiological correlates of the sensory modulation difficulties, we recorded magnetic field responses to clicks in 14 ASD and 15 typically developing (TD) children. We further analyzed the P100m, which is the most prominent component of the auditory magnetic field response in children and may reflect preattentive arousal processes. The P100m was rightward lateralized in the TD, but not in the ASD children, who showed a tendency toward P100m reduction in the right hemisphere (RH). The atypical P100m lateralization in the ASD subjects was associated with greater severity of sensory abnormalities assessed by Short Sensory Profile, as well as with auditory hypersensitivity during the first two years of life. The absence of right-hemispheric predominance of the P100m and a tendency for its right-hemispheric reduction in the ASD children suggests disturbance of the RH ascending reticular brainstem pathways and/or their thalamic and cortical projections, which in turn may contribute to abnormal arousal and attention. The correlation of sensory abnormalities with atypical, more leftward, P100m lateralization suggests that reduced preattentive processing in the right hemisphere and/or its shift to the left hemisphere may contribute to abnormal sensory behavior in ASD.
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| 43. |
- Orekhova, Elena V, 1967, et al.
(författare)
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Auditory Magnetic Response to Clicks in Children and Adults: Its Components, Hemispheric Lateralization and Repetition Suppression Effect
- 2013
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Ingår i: Brain Topography. - : Springer Science and Business Media LLC. - 0896-0267 .- 1573-6792. ; 26:3, s. 410-427
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Tidskriftsartikel (refereegranskat)abstract
- The auditory magnetic event-related fields (ERF) qualitatively change through the child development, reflecting maturation of auditory cortical areas. Clicks presented with long inter-stimulus interval produce distinct ERF components, and may appear useful to characterize immature EFR morphology in children. The present study is aimed to investigate morphology of the auditory ERFs in school-age children, as well as lateralization and repetition suppression of ERF components evoked by the clicks. School-age children and adults passively listened to pairs of click presented to the right ear, left ear or binaurally, with 8-11 s intervals between the pairs and a 1 s interval within a pair. Adults demonstrated a typical P50m/N100m response. Unlike adults, children had two distinct components preceding the N100m-P50m (at similar to 65 ms) and P100m (at similar to 100 ms). The P100m dominated the child ERF, and was most prominent in response to binaural stimulation. The N100m in children was less developed than in adults and partly overlapped in time with the P100m, especially in response to monaural clicks. Strong repetition suppression was observed for P50m both in children and adults, P100m in children and N100m in adults. Both children and adults demonstrated ERF amplitude and/or latency right hemispheric advantage effects that may reflect right hemisphere dominance for preattentive arousal processes. Our results contribute to the knowledge concerning development of auditory processing and its lateralization in children and have implications for investigation of the auditory evoked fields in developmental disorders.
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| 44. |
- Orekhova, Elena V, 1967, et al.
(författare)
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EEG theta rhythm in infants and preschool children.
- 2006
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Ingår i: Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology. - : Elsevier BV. - 1388-2457. ; 117:5, s. 1047-62
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To study behavioral correlates of theta oscillations in infants and preschool children. METHODS: EEG was recorded during baseline (visual attention) and two test conditions--exploration of toys and attention to 'social' stimulation. Age specific frequency boundaries of theta and mu rhythms were assessed using narrow bin analysis of EEG spectra. RESULTS: Theta spectral power increased whereas mu power decreased under test conditions in both age groups. In preschoolers theta rhythm increased predominantly over anterior regions during exploratory behavior and over posterior regions during attention to social stimulation. Theta frequency range changed with age from 3.6 to 5.6 Hz in infants to 4-8 Hz in children, and mu range from 6.4-8.4 Hz to 8.4-10.4 Hz. CONCLUSIONS: In early life, theta oscillations are strongly related to behavioral states with substantial attentional and emotional load. The scalp distribution of theta spectral power depends on age and behavioral condition and may reflect engagement of different brain networks in control of behavior. SIGNIFICANCE: The findings contribute to the scanty knowledge about the developmental course of theta rhythm. Data on behavioral correlates of theta rhythm in early life may improve our understanding of cognitive and mental processes in healthy and neuropsychiatrically diseased children.
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| 45. |
- Orekhova, Elena V, 1967, et al.
(författare)
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Excess of high frequency electroencephalogram oscillations in boys with autism.
- 2007
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Ingår i: Biological Psychiatry. - : Elsevier BV. - 0006-3223. ; 62:9, s. 1022-1099
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: An elevated excitation/inhibition ratio has been suggested as one mechanism underpinning autism. An imbalance between cortical excitation and inhibition may manifest itself in electroencephalogram (EEG) abnormalities in the high frequency range. The aim of this study was to investigate whether beta and gamma range EEG abnormalities are characteristic for young boys with autism (BWA). METHODS: EEG was recorded during sustained visual attention in two independent samples of BWA from Moscow and Gothenburg, aged 3 to 8 years, and in age matched typically developing boys (TDB). High frequency EEG spectral power was analyzed. RESULTS: In both samples, BWA demonstrated a pathological increase of gamma (24.4-44.0 Hz) activity at the electrode locations distant from the sources of myogenic artefacts. In both samples, the amount of gamma activity correlated positively with degree of developmental delay in BWA. CONCLUSIONS: The excess of high frequency oscillations may reflect imbalance in the excitation-inhibition homeostasis in the cortex. Given the important role of high frequency EEG rhythms for perceptual and cognitive processes, early and probably genetically determined abnormalities in the neuronal mechanisms generating high frequency EEG rhythms may contribute to development of the disorder. Further studies are needed to investigate the specificity of the findings for autism.
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| 46. |
- Orekhova, Elena V, 1967, et al.
(författare)
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Sensory gating in young children with autism: relation to age, IQ, and EEG gamma oscillations.
- 2008
-
Ingår i: Neuroscience Letters. - : Elsevier BV. - 0304-3940. ; 434:2, s. 218-223
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Tidskriftsartikel (refereegranskat)abstract
- Unusual reactions to auditory stimuli are often observed in autism and may relate to ineffective inhibitory modulation of sensory input (sensory gating). A previous study of P50 sensory gating did not reveal abnormalities in high-functioning school age children [C. Kemner, B. Oranje, M.N. Verbaten, H. van Engeland, Normal P50 gating in children with autism, J. Clin. Psychiatry 63 (2002) 214-217]. Sensory gating deficit may, however, characterize younger children with autism or be a feature of retarded children with autism, reflecting imbalance of neuronal excitation/inhibition in these cohorts. We applied a paired clicks paradigm to study P50 sensory gating, and its relation to IQ and EEG gamma spectral power (as a putative marker of cortical excitability), in young (3-8 years) children with autism (N=21) and age-matched typically developing children (N=21). P50 suppression in response to the second click was normal in high-functioning children with autism, but significantly (p<0.03) reduced in those with mental retardation. P50 gating improved with age in both typically developing children and those with autism. Higher ongoing EEG gamma power corresponded to lower P50 suppression in autism (p<0.02), but not in control group. The data suggest that ineffective inhibitory control of sensory processing is characteristic for retarded children with autism and may reflect excitation/inhibition imbalance in this clinical group.
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| 47. |
- Orekhova, Elena V, 1967, et al.
(författare)
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The right hemisphere fails to respond to temporal novelty in autism: evidence from an ERP study.
- 2009
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Ingår i: Clinical Neurophysiology. - : Elsevier BV. - 1388-2457. ; 120:3, s. 520-529
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: This study aimed to investigate electrophysiological correlates of initial attention orienting to temporally novel sound in children with autism (CWA). METHODS: Twenty-one CWA (4-8 years) and 21 age-matched typically developing children (TDC) were presented with pairs of clicks separated by a 0.5s intra-pair interval, with longer (7-9s) intervals between pairs. Children watched a silent movie during click presentation. We assessed EEG perturbations and event-related potentials (ERP) in response to sounds of different temporal novelty - first (S1) and second (S2) clicks in the pair. RESULTS: In TDC, the early attention-modulated midtemporal N1c wave evoked by S1 and corresponding EEG phase locking and power increase were right-lateralized and were bilaterally higher than those evoked by S2. CWA demonstrated abnormal S1 responses, characterized by reduced N1c amplitude and EEG phase locking in the right midtemporal region, reversed leftward lateralization of the phase locking, and diminished later frontal N2 wave. Their brain responses to S2 were essentially normal. CONCLUSIONS: The impaired right hemispheric processing of temporary and contextually novel information and suboptimal lateralization of normally right-lateralized attention networks may be important features of autistic disorder. SIGNIFICANCE: Results of this study contribute to the understanding of autism neurobiology.
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| 48. |
- Orekhova, Elena V, 1967, et al.
(författare)
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Unraveling superimposed EEG rhythms with multi-dimensional decomposition.
- 2011
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Ingår i: Journal of neuroscience methods. - : Elsevier BV. - 1872-678X .- 0165-0270. ; 195:1, s. 47-60
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Tidskriftsartikel (refereegranskat)abstract
- Scalp-recorded EEG activity reflects a number of oscillatory phenomena, many of which are generated by coupled brain sources or behave as travelling waves. Decomposition of EEG oscillations into sets of coherent processes may help investigation of the underlying functional brain networks. Traditional decomposition methods, such as ICA and PCA, cannot satisfactorily characterize coherent EEG oscillations. Moreover, these methods impose non-physiological constraints (orthogonality, maximal time independence) on the solutions. We introduce the C(3)R-MDD method, that is based on recursive multi-dimensional decomposition (R-MDD). The method allows separation of ongoing EEG into a predefined number of coherent oscillatory processes. Applied to a multichannel complex cross-correlation array (C(3)), the method extracts oscillatory processes characterized by a dominant frequency, spatial amplitude-phase distribution, and stability in time. Introduction of an additional dimension of experimental conditions allows characterization of condition-related dynamics of the processes. In this study, we first used C(3)R-MDD to decompose a simulated signal created by superposition of components with known properties. Meaningful solutions were obtained even with a suboptimal number of components in the model. Second, we applied the method to decompose rhythmic processes in ongoing low- and high-frequency EEG records of two subjects and demonstrated good reproducibility of the components obtained with different solutions, two halves of the EEG record, and different experimental sessions. The C(3)R-MDD method is compared with other types of signal decomposition: real-numbers ICA and real-numbers MDD.
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| 49. |
- Reinsfelt, Björn, et al.
(författare)
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The effects of isoflurane-induced electroencephalographic burst suppression on cerebral blood flow velocity and cerebral oxygen extraction during cardiopulmonary bypass.
- 2003
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Ingår i: Anesthesia and analgesia. - 0003-2999. ; 97:5, s. 1246-50
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Tidskriftsartikel (refereegranskat)abstract
- We investigated the effects of isoflurane-induced burst suppression, monitored with electroencephalography (EEG), on cerebral blood flow velocity (CBFV), cerebral oxygen extraction (COE), and autoregulation in 16 patients undergoing cardiac surgery. The experimental procedure was performed during nonpulsatile cardiopulmonary bypass (CPB) with mild hypothermia (32 degrees C) in fentanyl-anesthestized patients. Middle cerebral artery transcranial Doppler flow velocity, right jugular vein bulb oxygen saturation, and jugular venous pressure (JVP) were continuously measured. Autoregulation was tested during changes in mean arterial blood pressure (MAP) within a range of 40-80 mm Hg, induced by sodium nitroprusside and phenylephrine before (control) and during additional isoflurane administration to an EEG burst-suppression level of 6-9/min. Isoflurane induced a 27% decrease in CBFV (P < 0.05) and a 13% decrease in COE (P < 0.05) compared with control. The slope of the positive relationship between CBFV and cerebral perfusion pressure (CPP = MAP - JVP) was steeper with isoflurane (P < 0.05) compared with control, as was the slope of the negative relationship between CPP and COE (P < 0.05). We conclude that burst-suppression doses of isoflurane decrease CBFV and impair autoregulation of cerebral blood flow during mildly hypothermic CPB. Furthermore, during isoflurane administration, blood flow was in excess relative to oxygen demand, indicating a loss of metabolic autoregulation of flow.
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- Rejnö-Habte Selassie, Gunilla, et al.
(författare)
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Cortical mapping of receptive language processing in children using navigated transcranial magnetic stimulation.
- 2020
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Ingår i: Epilepsy & behavior : E&B. - : Elsevier BV. - 1525-5069. ; 103:A
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Tidskriftsartikel (refereegranskat)abstract
- We used a stepwise process to develop a new paradigm for preoperative cortical mapping of receptive language in children, using temporary functional blocking with transcranial magnetic stimulation (TMS). The method combines short sentences with a lexical decision task in which children are asked to point at a picture that fits a short sentence delivered aurally. This was first tested with 24 healthy children aged 4-16years. Next, 75 sentences and 25 slides were presented to five healthy children in a clinical setting without TMS. Responses were registered on a separate computer, and facial expressions and hand movements were filmed for later offline review. Technical adjustments were made to combine these elements with the existing TMS equipment. The audio-recorded sentences were presented before the visual stimuli. Sentence lists were constructed to avoid similar stimuli in a row. Two different baseline lists were used before the TMS registration; the second baseline resulted in faster responses and was chosen as the reference for possible response delays induced by TMS. Protocols for offline reviews were constructed. No response, incorrect response, self-correction, delayed response, and perseveration were considered clear stimulation effects, while poor attention, discomfort, and other events were regarded as unclear. Finally, three children (6:2, 14:0, 14:10years) with epilepsy and expected to undergo neurosurgery were assessed using TMS (left hemisphere in one; both hemispheres in the other two). In the two assessed bilaterally, TMS effects indicated bilateral language processing. Delayed response was the most common error. This is a first attempt to develop a new TMS paradigm for receptive language mapping, and further evaluation is suggested.
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