Publications by authors named "Christian Svane"

13 Publications

  • Page 1 of 1

Transcranial Alternating Current Stimulation of the Primary Motor Cortex after Skill Acquisition Improves Motor Memory Retention in Humans: A Double-Blinded Sham-Controlled Study.

Cereb Cortex Commun 2020 6;1(1):tgaa047. Epub 2020 Aug 6.

Department of Neuroscience, University of Copenhagen, 2200 Copenhagen, Denmark.

Consolidation leading to retention of motor memory following motor practice involves activity-dependent plastic processes in the corticospinal system. To investigate whether beta-band transcranial alternating current stimulation (tACS) applied immediately following skill acquisition can enhance ongoing consolidation processes and thereby motor skill retention 20 adults participated in a randomized, double-blinded, sham-controlled study. Participants received tACS at peak beta-band corticomuscular coherence (CMC) frequency or sham tACS for 10 min following practice of a visuomotor ankle dorsiflexion task. Performance was measured as the average percentage time on target. Electroencephalograhy (EMG) was measured at Cz and EMG from the right tibialis anterior muscle. CMC and intramuscular coherence (IMC) were estimated during 2-min tonic dorsiflexion. Motor skill retention was tested 1 and 7 days after motor practice. From the end of motor practice to the retention tests, motor performance improved more in the tACS group compared with the sham tACS group after 1 ( = 0.05) and 7 days ( < 0.001). At both retention tests, beta-band IMC increased in the tACS group compared with post-tACS. Beta-band CMC increased in the tACS group at retention day 1 compared with post-tACS. Changes in CMC but not IMC were correlated with performance 1 and 7 days following practice. This study shows that tACS applied at beta-band CMC frequency improves consolidation following visuomotor practice and increases beta-band CMC and IMC. We propose that oscillatory beta activity in the corticospinal system may facilitate consolidation of the motor skill.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/texcom/tgaa047DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8152838PMC
August 2020

Nonsurgical Treatment Options for Muscle Contractures in Individuals With Neurologic Disorders: A Systematic Review With Meta-Analysis.

Arch Rehabil Res Clin Transl 2021 Mar 13;3(1):100104. Epub 2021 Jan 13.

Department of Neuroscience, University of Copenhagen, Copenhagen.

Objective: To investigate whether nonsurgical treatment can reduce muscle contractures in individuals with neurologic disorders. The primary outcome measure was muscle contractures measured as joint mobility or passive stiffness.

Data Sources: Embase, MEDLINE, Cumulative Index to Nursing and Allied Health, and Physiotherapy Evidence Database in June-July 2019 and again in July 2020.

Study Selection: The search resulted in 8020 records, which were screened by 2 authors based on our patient, intervention, comparison, outcome criteria. We included controlled trials of nonsurgical interventions administered to treat muscle contractures in individuals with neurologic disorders.

Data Extraction: Authors, participant characteristics, intervention details, and joint mobility/passive stiffness before and after intervention were extracted. We assessed trials for risk of bias using the Downs and Black checklist. We conducted meta-analyses investigating the short-term effect on joint mobility using a random-effects model with the pooled effect from randomized controlled trials (RCTs) as the primary outcome. The minimal clinically important effect was set at 5°.

Data Synthesis: A total of 70 trials (57 RCTs) were eligible for inclusion. Stretch had a pooled effect of 3° (95% CI, 1-4°; prediction interval (PI)=-2 to 7°; =66%; <.001), and robot-assisted rehabilitation had an effect of 1 (95% CI, 0-2; PI=-8 to 9; =73%; =.03). We found no effect of shockwave therapy (=.56), physical activity (=.27), electrical stimulation (=.11), or botulinum toxin (=.13). Although trials were generally of moderate to high quality according to the Downs and Black checklist, only 18 of the 70 trials used objective measures of muscle contractures. In 23 trials, nonobjective measures were used without use of assessor-blinding.

Conclusions: We did not find convincing evidence supporting the use of any nonsurgical treatment option. We recommend that controlled trials using objective measures of muscle contractures and a sufficiently large number of participants be performed.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.arrct.2021.100104DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7984980PMC
March 2021

Sustained involuntary muscle activity in cerebral palsy and stroke: same symptom, diverse mechanisms.

Brain Commun 2019 25;1(1):fcz037. Epub 2019 Nov 25.

Department of Neuroscience, University of Copenhagen, 2200 Copenhagen, Denmark.

Individuals with lesions of central motor pathways frequently suffer from sustained involuntary muscle activity. This symptom shares clinical characteristics with dystonia but is observable in individuals classified as spastic. The term spastic dystonia has been introduced, although the underlying mechanisms of involuntary activity are not clarified and vary between individuals depending on the disorder. This study aimed to investigate the nature and pathophysiology of sustained involuntary muscle activity in adults with cerebral palsy and stroke. Seventeen adults with cerebral palsy (Gross Motor Function Classification System I-V), 8 adults with chronic stroke and 14 control individuals participated in the study. All individuals with cerebral palsy or stroke showed increased resistance to passive movement with Modified Ashworth Scale >1. Two-minute surface EMG recordings were obtained from the biceps muscle during attempted rest in three positions of the elbow joint; a maximally flexed position, a 90-degree position and a maximally extended position. Cross-correlation analysis of sustained involuntary muscle activity from individuals with cerebral palsy and stroke, and recordings of voluntary isometric contractions from control individuals were performed to examine common synaptic drive. In total, 13 out of 17 individuals with cerebral palsy and all 8 individuals with stroke contained sustained involuntary muscle activity. In individuals with cerebral palsy, the level of muscle activity was not affected by the joint position. In individuals with stroke, the level of muscle activity significantly ( < 0.05) increased from the flexed position to the 90 degree and extended position. Cumulant density function indicated significant short-term synchronization of motor unit activities in all recordings. All groups exhibited significant coherence in the alpha (6-15 Hz), beta (16-35 Hz) and early gamma band (36-60 Hz). The cerebral palsy group had lower alpha band coherence estimates, but higher gamma band coherence estimates compared with the stroke group. Individuals with increased resistance to passive movement due to cerebral palsy or stroke frequently suffer sustained involuntary muscle activity, which cannot exclusively be described by spasticity. The sustained involuntary muscle activity in both groups originated from a common synaptic input to the motor neuron pool, but the generating mechanisms could differ between groups. In cerebral palsy it seemed to originate more from central mechanisms, whereas peripheral mechanisms likely play a larger role in stroke. The sustained involuntary muscle activity should not be treated simply like the spinal stretch reflex mediated symptom of spasticity and should not either be treated identically in both groups.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1093/braincomms/fcz037DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7531180PMC
November 2019

Time from injury to arrival at the trauma centre in patients undergoing interhospital transfer.

Dan Med J 2020 Aug 31;67(9). Epub 2020 Aug 31.

Introduction: Trauma patients may require interhospital transfer to definitive care following initial assessment at a primary facility. A prolonged time to transfer may be associated with a poor outcome. The aim of this study was to determine the time from injury to arrival in patients undergoing interhospital transfer to the Trauma Centre at Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.

Methods: Data were obtained from our local trauma registry for the period from 1 November 2016 to 31 October 2019. We included patients who underwent interhospital transfer to our trauma centre. Patients were compared according to a 360-minute time interval between injury and arrival.

Results: In the study period, 250 patients underwent interhospital transfer to our trauma centre. The median age was 47 years (interquartile range (IQR) 26-65), the majority were male (68.4%) and a total of 113 patients (46.9%) had an Injury Severity Score (ISS) > 15. The 30-day mortality was 6% (95% confidence interval (CI) 3.6-9.7). The median time from injury to arrival at our trauma centre was 255 minutes (IQR 192-371). We found that 67 patients (27%; 95% CI 21.7-32.6) arrived at our trauma centre more than 360 minutes after time of injury. The patients arriving later than 360 minutes were significantly older (p = 0.004) than the remaining patients. There was no significant difference in the unadjusted 30-day mortality (odds ratio (OR) 1.01, 95% CI 0.3-3.3).

Conclusions: Time from injury to arrival at our trauma centre exceeded 360 minutes for 67 patients (27%) who were significantly older than the remaining patients transferred.

Funding: departmental funding.

Trial Registration: not relevant.
View Article and Find Full Text PDF

Download full-text PDF

Source
August 2020

Transcutaneous spinal direct current stimulation increases corticospinal transmission and enhances voluntary motor output in humans.

Physiol Rep 2020 08;8(16):e14531

Department of Neuroscience, University of Copenhagen, Copenhagen N, Denmark.

Optimization of motor performance is of importance in daily life, in relation to recovery following injury as well as for elite sports performance. The present study investigated whether transcutaneous spinal direct current stimulation (tsDCS) may enhance voluntary ballistic activation of ankle muscles and descending activation of spinal motor neurons in able-bodied adults. Forty-one adults (21 men; 24.0 ± 3.2 years) participated in the study. The effect of tsDCS on ballistic motor performance and plantar flexor muscle activation was assessed in a double-blinded sham-controlled cross-over experiment. In separate experiments, the underlying changes in excitability of corticospinal and spinal pathways were probed by evaluating soleus (SOL) motor evoked potentials (MEPs) following single-pulse transcranial magnetic stimulation (TMS) over the primary motor cortex, SOL H-reflexes elicited by tibial nerve stimulation and TMS-conditioning of SOL H-reflexes. Measures were obtained before and after cathodal tsDCS over the thoracic spine (T11-T12) for 10 min at 2.5 mA. We found that cathodal tsDCS transiently facilitated peak acceleration in the ballistic motor task compared to sham tsDCS. Following tsDCS, SOL MEPs were increased without changes in H-reflex amplitudes. The short-latency facilitation of the H-reflex by subthreshold TMS, which is assumed to be mediated by the fast conducting monosynaptic corticomotoneuronal pathway, was also enhanced by tsDCS. We argue that tsDCS briefly facilitates voluntary motor output by increasing descending drive from corticospinal neurones to spinal plantar flexor motor neurons. tsDCS can thus transiently promote within-session CNS function and voluntary motor output and holds potential as a technique in the rehabilitation of motor function following central nervous lesions.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.14814/phy2.14531DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7435034PMC
August 2020

Unannounced vs announced in situ simulation of emergency teams: Feasibility and staff perception of stress and learning.

Acta Anaesthesiol Scand 2019 05 15;63(5):684-692. Epub 2019 Jan 15.

The Juliane Marie Centre for Children, Women and Reproduction, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.

Background: Simulation-based medical education, often used for teaching teamwork, can be conducted in different settings: off-site (simulation centers or other settings away from clinical units) or in situ (real clinical environment), where the latter can be either announced or unannounced. Simulation in general, but especially unannounced in situ simulation, has been described as stressful and stress can affect learning. The aim of this study was to evaluate feasibility and the perception of learning and stress.

Methods: Sixteen standardized in situ simulations were planned in an emergency department on eight predetermined dates, with one unannounced and one announced simulation per day. Authentic ad hoc teams were formed based on the on-call staff and included doctors, nurses, radiographers, biochemist, porters, and secretaries. Data were collected using questionnaires and the State-Trait Anxiety Inventory.

Results: Eleven of the 16 in situ simulations were completed. Self-perceived learning was "good" or "very good" for 27/47 (57%) participants and 33/50 (66%) in unannounced vs announced in situ simulation (P = 0.33). Two of 47 (4%) in unannounced in situ simulation "agreed or partly agreed" that in situ simulation was stressful or unpleasant vs 12/50 (24%) in announced in situ simulation (P = 0.06).

Conclusion: No significant difference was found between unannounced and announced in situ simulation among emergency department staff according to self-perceived learning and self-perceived stress. This is relevant for the future planning of simulation when considering what is to be achieved from implementing different designs for simulation-based medical education.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/aas.13321DOI Listing
May 2019

Spasticity in adults with cerebral palsy and multiple sclerosis measured by objective clinically applicable technique.

Clin Neurophysiol 2018 09 24;129(9):2010-2021. Epub 2018 Jul 24.

Institute of Neuroscience, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark; Department of Nutrition, Exercise and Sports and Elsass Institute, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark. Electronic address:

Objective: The present study evaluated ankle stiffness in adults with and without neurological disorders and investigated the accuracy and reproducibility of a clinically applicable method using a dynamometer.

Methods: Measurements were obtained from 8 healthy subjects (age 39.3), 9 subjects with spastic cerebral palsy (CP) (age 39.8) and 8 subjects with multiple sclerosis (MS) (age 49.9). Slow and fast dorsiflexion stretches of the ankle joint were performed to evaluate passive muscle-tendon-joint stiffness, reflex mediated stiffness and range of movement (ROM), respectively. Intra/inter-rater reliability for passive and reflex mediated ankle muscle stiffness was assessed for all groups.

Results: Subjects with CP and MS showed significantly larger values of passive stiffness in the triceps surae muscle tendon complex and smaller ROM compared to healthy individuals, while no significant difference in reflex mediated stiffness. Measurements of passive muscle-tendon-joint stiffness and reflex mediated stiffness showed good to excellent inter- and intra-rater reliability (ICC: 0.62-0.91) in all groups.

Conclusion: Increased stiffness was found in subjects with CP and MS with a clinically applicable method that provides valid and reproducible measurement of passive ankle muscle-tendon-joint stiffness and reflex mediated stiffness.

Significance: The present technique may provide important supplementary information for the clinician.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.clinph.2018.07.004DOI Listing
September 2018

Feedforward neural control of toe walking in humans.

J Physiol 2018 06 15;596(11):2159-2172. Epub 2018 Apr 15.

Department of Neuroscience, University of Copenhagen, Copenhagen, Denmark.

Key Points: Activation of ankle muscles at ground contact during toe walking is unaltered when sensory feedback is blocked or the ground is suddenly dropped. Responses in the soleus muscle to transcranial magnetic stimulation, but not peripheral nerve stimulation, are facilitated at ground contact during toe walking. We argue that toe walking is supported by feedforward control at ground contact.

Abstract: Toe walking requires careful control of the ankle muscles in order to absorb the impact of ground contact and maintain a stable position of the joint. The present study aimed to clarify the peripheral and central neural mechanisms involved. Fifteen healthy adults walked on a treadmill (3.0 km h ). Tibialis anterior (TA) and soleus (Sol) EMG, knee and ankle joint angles, and gastrocnemius-soleus muscle fascicle lengths were recorded. Peripheral and central contributions to the EMG activity were assessed by afferent blockade, H-reflex testing, transcranial magnetic brain stimulation (TMS) and sudden unloading of the planter flexor muscle-tendon complex. Sol EMG activity started prior to ground contact and remained high throughout stance. TA EMG activity, which is normally seen around ground contact during heel strike walking, was absent. Although stretch of the Achilles tendon-muscle complex was observed after ground contact, this was not associated with lengthening of the ankle plantar flexor muscle fascicles. Sol EMG around ground contact was not affected by ischaemic blockade of large-diameter sensory afferents, or the sudden removal of ground support shortly after toe contact. Soleus motor-evoked potentials elicited by TMS were facilitated immediately after ground contact, whereas Sol H-reflexes were not. These findings indicate that at the crucial time of ankle stabilization following ground contact, toe walking is governed by centrally mediated motor drive rather than sensory driven reflex mechanisms. These findings have implications for our understanding of the control of human gait during voluntary toe walking.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1113/JP275539DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5983220PMC
June 2018

Characterization of corticospinal activation of finger motor neurons during precision and power grip in humans.

Exp Brain Res 2018 03 10;236(3):745-753. Epub 2018 Jan 10.

Department of Nutrition, Exercise and Sports, University of Copenhagen, Panum Institute 33.3, Blegdamsvej 3, 2200, Copenhagen, Denmark.

Direct and indirect corticospinal pathways to finger muscles may play a different role in control of the upper extremity. We used transcranial magnetic stimulation (TMS) and coherence analysis to characterize the corticospinal drive to the first dorsal interosseous (FDI) and abductor pollicis brevis (APB) when active during a precision and power grip task. In experiment 1, single motor units were recorded during precision grip and power grip in 20 adults (25.2 ± 7.1 years). Post-stimulus time histograms (PSTH) were obtained following TMS. In experiment 2, coherence and cross-correlation analysis of the FDI and APB surface EMG were used to investigate the temporal organization of corticospinal drive during precision grip and power grip in 15 adults (27.4 ± 8.1 years). We found no significant differences in PSTH peak onset (26.6 ± 1.9 vs. 26.7 ± 2.0 ms, p = 0.75), maximal peak (27.4 ± 1.9 vs. 27.4 ± 1.9 ms, p = 1.0) or peak duration (2.3 ± 1.1 vs. 2.3 ± 1.0 ms, p = 0.75) for the 11 recovered motor units during precision grip and power grip. Also, no significant difference in coherence or the width of the synchronization peaks during precision grip (7.2 ± 3.7 ms) and power grip (7.9 ± 3.1 ms) could be observed (p = 0.59). The short duration of peaks elicited in the PSTH of single motor units following TMS and central synchronization peaks of voluntarily activated motor units during precision and power grip suggests that the direct corticospinal pathway (the corticomotoneuronal system) is equally involved in the control of both tasks. The data do not support that indirect pathways would make a larger contribution to power grip.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s00221-018-5171-0DOI Listing
March 2018

Is there a diurnal difference in mortality of severely injured trauma patients?

Emerg Med J 2015 Apr 6;32(4):287-90. Epub 2013 Dec 6.

Department of Anaesthesia, Center of Head and Orthopaedics, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark.

Background: Mortality may be higher for admissions at odd hours than during daytime, although for trauma patients results are conflicting. The objective of this study was to assess whether diurnal differences in mortality among severely injured trauma patients in Denmark were present.

Methods: This observational cohort study was conducted between 1 December 2009 and 30 April 2011 involving one level 1 trauma centre and seven local emergency departments in eastern Denmark. Patients were consecutively included if received by a designated trauma team. Night-time patients (20:00-07:59) were compared with daytime patients (20:00-07:59). An injury severity score (ISS) >15 defined severe injury. Patients with burns and patients who upon arrival were declared non-trauma patients were not included. The primary outcome measure was 30-day mortality.

Results: A total of 1985 patients were recorded, of whom 576 were admitted at night-time, 1369 at daytime and 40 not included due to missing data. There were 142 patients with ISS >15 in the daytime group and 64 at night-time. The 30-day mortality was 14.1% for admittance at night-time versus 21.3% at daytime (p=0.22). Logistic regression analysis revealed that odd-hour admission was not a significant predictor of mortality for patients with ISS >15 when adjusted for age, ISS and initial treatment facility (OR 0.71 (95% CI 0.27 to 1.90); p=0.50).

Conclusions: In conclusion, we found no diurnal differences in 30-day mortality for severely injured trauma patients.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1136/emermed-2013-202754DOI Listing
April 2015

Effect of prehospital ultrasound on clinical outcomes of non-trauma patients--a systematic review.

Resuscitation 2014 Jan 19;85(1):21-30. Epub 2013 Sep 19.

The Emergency Medical Services in Copenhagen, Denmark; Centre of Head and Orthopaedics, Department of Anaesthesia, Rigshospitalet, Denmark.

Background: Advances in technology have made prehospital ultrasound (US) examination available. Whether US in the prehospital setting can lead to improvement in clinical outcomes is yet unclear.

Objective: The aim of this systematic review was to assess whether prehospital US improves clinical outcomes for non-trauma patients.

Method: We conducted a systematic review on non-trauma patients who had an US examination performed in the prehospital setting. We searched MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials and the ISI Web of Science and the references of the included studies for additional relevant studies. We then performed a risk of bias analysis and descriptive data analysis.

Results: We identified 1707 unique citations and included ten studies with a total of 1068 patients undergoing prehospital US examination. Included publications ranged from case series to non-randomized, descriptive studies, and all showed a high risk of bias. The large heterogeneity between the different studies made further statistical analysis impossible.

Conclusion: There are currently no randomized, controlled studies on the use of US for non-trauma patients in the prehospital setting. The included studies were of large heterogeneity and all showed a high risk of bias. We were thus unable to assess the effect of prehospital US on clinical outcomes. However, consistent reports suggested that US may improve patient management with respect to diagnosis, treatment, and hospital referral.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.resuscitation.2013.09.012DOI Listing
January 2014

[Fatal course of a patient during in vitro fertilisation treatment].

Ugeskr Laeger 2010 May;172(20):1537-8

Anaestesi- og Operationsklinikken, HovedOrtoCentret, Rigshospitalet, 2100 København Ø, Denmark.

Chylomicronaemia syndrome is a rare disorder primarily caused by a genetic defect which increases triglycerides, combined with a secondary inducing factor. We describe the fatal course of a 33-year-old, pregnant woman with known dyslipidaemia who had been treated with in vitro fertilisation and developed chylomicronaemia syndrome with severe hypertriglyceridaemia, hypertriglyceridaemia-induced acute pancreatitis and septic shock. Appropriate treatment including close monitoring, severe restriction of dietary fat intake and early plasmapheresis is emphasized - especially during pregnancy.
View Article and Find Full Text PDF

Download full-text PDF

Source
May 2010

[Adverse reactions to anthrax vaccination in Danish military personnel deployed to Iraq].

Ugeskr Laeger 2005 Sep;167(36):3393-6

Reservelaege Christian Svane, reservelaege Morten Sonne & stabslaege Lars Ravnborg Nissen.

Introduction: On Denmark's decision to join the war in Iraq, it was decided to immunise all personnel to be deployed there with anthrax vaccine. This paper describes the types and frequency of adverse reactions to the vaccine.

Materials And Methods: Between March 2003 and February 2004, 1,899 immunisations against anthrax in 755 personnel were registered at the health care facilities of the Danish Defence.

Results: No serious or life-threatening adverse reactions were reported. The data showed a statistically significant decrease in adverse reactions between the four immunisation series. For males, adverse reactions after the second immunisation depended on possible adverse reactions to the first immunisation. In females, this correlation was not found. No differences in the frequency of adverse reactions between males and females were found.

Discussion: None of the vaccinated persons suffered serious or life-threatening adverse reactions. Compared to other studies on self-reported adverse reactions, the overall frequency was low. The data showed a statistically significant decrease in adverse reactions between the four immunisation series. This has been described in comparable studies. The correlation between adverse reactions in the second immunisation being dependent on adverse reactions to the first immunisation has been partly confirmed by other studies. No differences between the sexes were found, probably because only a few females were included in the study. In case of a significant level of threat concerning biological weapons, immunisation against anthrax is considered appropriate.
View Article and Find Full Text PDF

Download full-text PDF

Source
September 2005
-->