To provide a systematic overview of interventions for stroke related visual impairments.
Transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (TDCS) are two types of non-invasive transcranial brain stimulation (TBS). They are useful tools for stroke research and may be potential adjunct therapies for functional recovery. However, stroke often causes large cerebral lesions, which are commonly accompanied by a secondary enlargement of the ventricles and atrophy. These structural alterations substantially change the conductivity distribution inside the head, which may have potentially important consequences for both brain stimulation methods. We therefore aimed to characterize the impact of these changes on the spatial distribution of the electric field generated by both TBS methods. In addition to confirming the safety of TBS in the presence of large stroke-related structural changes, our aim was to clarify whether targeted stimulation is still possible. Realistic head models containing large cortical and subcortical stroke lesions in the right parietal cortex were created using MR images of two patients. For TMS, the electric field of a double coil was simulated using the finite-element method. Systematic variations of the coil position relative to the lesion were tested. For TDCS, the finite-element method was used to simulate a standard approach with two electrode pads, and the position of one electrode was systematically varied. For both TMS and TDCS, the lesion caused electric field “hot spots” in the cortex. However, these maxima were not substantially stronger than those seen in a healthy control. The electric field pattern induced by TMS was not substantially changed by the lesions. However, the average field strength generated by TDCS was substantially decreased. This effect occurred for both head models and even when both electrodes were distant to the lesion, caused by increased current shunting through the lesion and enlarged ventricles. Judging from the similar peak field strengths compared to the healthy control, both TBS methods are safe in patients with large brain lesions (in practice, however, additional factors such as potentially lowered thresholds for seizure-induction have to be considered). Focused stimulation by TMS seems to be possible, but standard tDCS protocols appear to be less efficient than they are in healthy subjects, strongly suggesting that tDCS studies in this population might benefit from individualized treatment planning based on realistic field calculations.
Transcranial brain stimulation (TBS) methods are useful tools to induce and to quantify neural plasticity, and as such are increasingly being used in stroke research and as potential adjunct therapies in stroke rehabilitation. The cerebral lesions caused by stroke result in persisting physical or cognitive impairments in around 50% of all survivors (Di Carlo, 2008; Leys et al., 2005 ; Young and Forster, 2007), meaning that new therapies are urgently needed. Transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (TDCS) are two TBS approaches which are being increasingly utilised in stroke research. Single-pulse TMS combined with electromyography (EMG) or electroencephalography (EEG) can be used to assess cortical excitability, for example to index the functional state of the perilesional tissue. The neuromodulatory effects of repetitive TMS protocols (rTMS) may, in association with neuro-rehabilitative treatments, enhance motor recovery (Liew et al., 2014). Similar results have been demonstrated for TDCS. For example, anodal TDCS of the hand area in the primary motor cortex has been shown to improve motor performance of the affected hand (Allman et al., 2016; Hummel et al., 2005 ; Stagg et al., 2012) and anodal TDCS applied over the left frontal cortex enhanced naming accuracy in patients with aphasia (Baker et al., 2010). However, not all studies report a clear-cut positive impact of TBS on the stroke symptoms. Rather, the observed effects are often weak and not consistent across patients, demonstrating the need for a better understanding of the underlying biophysical and physiological mechanisms.
Compared with healthy subjects, several factors might contribute to a change in the neuroplastic response to TBS protocols in stroke patients, including changes in the neural responsiveness to the applied electric fields, as well as differences in the underlying physiology and metabolism (Blicher et al., 2009; Blicher et al., 2015 ; O’Shea et al., 2014). When the lesions are large, they may also substantially alter the generated electric field pattern, meaning that the assumptions on spatial targeting as derived from biophysical modelling and physiological experiments in healthy subjects might no longer be valid. Stroke lesions are often accompanied by secondary macrostructural changes such as cortical atrophy and enlargement of the ventricles (e.g., Skriver et al., 1990), which may further contribute to changes in the field pattern. In addition, the safety of TBS in patients with large lesions needs to be further clarified, as it is possible that the lesions might cause stimulation “hot spots”. In chronic patients, the stroke cavity becomes filled with corticospinal fluid (CSF), which might cause shunting of current, funnelling the generated currents towards the surrounding brain tissue and potentially causing localized areas of dangerously high field strengths.
Here, using finite-element calculations and individual head models derived from structural MR images, we focused on the impact of a large cortical lesion in chronic stroke on the electric field pattern generated in the brain by TMS and TDCS, respectively. Firstly, we assessed the safety of the stimulation by comparing the achieved field strengths with those estimated for a healthy control. Secondly, we tested how reliably we can accurately target the perilesional tissue, often the desired target for TBS, as reorganisation here is thought to underpin functional recovery (Kwakkel et al., 2004). Finally, we were also interested to see whether any observed changes in the field pattern were specific to a patient with a cortical lesion (which is connected to the CSF layer underneath the skull), or whether similar effects might occur in case of large chronic subcortical lesion. We therefore additionally tested the field distribution in a head model of a patient with a subcortical lesion occurring at a similar position as the cortical lesion.
The aim of this study was to characterize the effect of a large chronic cortical stroke lesion on the electric field distribution generated by TBS, and to compare the effects of this lesion to that caused by a large chronic subcortical lesion. MR images of several patients were visually inspected to select two datasets, which had a cortical [P01] and subcortical lesion [P02], respectively, within the same gross anatomical regions.
Patient P01 was a 36 year old female with episodic migraine; she was admitted with left hemiparalysis, fascial palsy and a total NIHSS score of 16 due to a right ICI/MCI occlusion. She was treated with IV thrombolysis and thrombectomy and recanalization was achieved 5 h after symptom onset. One year post-stroke she still suffered from motor impairment (Wolf Motor Function Test [WMFT] score of 30) and was scanned as part of a clinical study investigating the effect of combining Constraint-Induced Movement Therapy and tDCS (Figlewski et al., 2017; Clinical trials NCT01983319, Regional Ethics approval: 1-10-72-268-13). The structural scans showed a cortical lesion in the right parietal lobe (Fig. 1A). The lesion volume, delineated manually with reference to T1- and T2-weighted imaging, was 26,415 mm3.
A) Coronal view of patient P01 with a cortical lesion in the right hemisphere. The top shows the T1-weighted MR image and the bottom the reconstructed head mesh. The view was chosen to include the lesion centre. The lesion is marked by red dashed circles. B) Corresponding view of patient P02 with a large subcortical lesion at a similar location in the right hemisphere. C) Corresponding view of the data set of the healthy control. D) The coil and electrode positions were systematically moved along two directions that were approximately perpendicular to each other. Five positions were manually placed every 2 cm in posterior – anterior direction symmetrically around the centre of the cortical lesion. The same was repeated along the lateral – medial direction. Both lines share the same centre position above the lesion, resulting in 9 positions in total. E) At each position, two coil orientations were tested which resulted in a current flow underneath the coil centre from anterior to posterior (top) and from lateral to medial, respectively (bottom). F) For each position of the yellow “stimulating” electrode, two positions of the blue return electrode were tested. First, the contralateral equivalent of the electrode position above the centre of the cortical lesion was used (top). In addition, a position on the contralateral forehead was tested (bottom).
by Lisa Kreber, Ph.D. CBIS
Senior Neuroscientist, Centre for Neuro Skills
What is Neuroplasticity?
How Neuroplasticity Works
Mechanisms of Plasticity
Modulation of Neurotransmission
Forms of Neuronal Plasticity
Depression and Hippocampal Plasticity
Ten Principles of Neuroplasticity
Learning, Injury and Recovery
Children whose mothers have taken anti-epilepsy medicine during pregnancy, do not visit the doctor more often than children who have not been exposed to this medicine in utero. This is the result of a new study from Aarhus.
Previous studies have shown that anti-epilepsy medicine may lead to congenital malformations in the foetus and that the use of anti-epilepsy medicine during pregnancy affects the development of the brain among the children. There is still a lack of knowledge in the area about the general health of children who are exposed to anti-epilepsy medicine in foetallife. But this new study is generally reassuring for women who need to take anti-epilepsy medicine during their pregnancy.
Being born to a mother who has taken anti-epilepsy medicine during pregnancy appears not to harm the child’s health. These are the findings of the first Danish study of the correlation between anti-epilepsy medicine and the general health of the child which has been carried out by the Research Unit for General Practice, Aarhus University and Aarhus University Hospital.
The results have just been published in the international scientific journal BMJ Open.
The researchers have looked into whether children who have been exposed to the mother’s anti-epilepsy medicine have contact with their general practitioner (GP) more often than other children – and there are no significant differences.
No reason til worry
“Our results are generally reassuring for women who need to take anti-epilepsy medicine during their pregnancy, including women with epilepsy,” says Anne Mette Lund Würtz, who is one of the researchers behind the project.
The difference in the number of contacts to the general practitioner between exposed and non-exposed children is only three per cent.
“The small difference we found in the number of contacts is primarily due to a difference in the number of telephone contacts and not to actual visits to the GP. At the same time, we cannot rule out that the difference in the number of contacts is caused by a small group of children who have more frequent contact with their GP because of illness,” explains Anne Mette Lund Würtz.
Of the 963,010 children born between 1997 and 2012, who were included in the survey, anti-epilepsy medicine was used in 4,478 of the pregnancies that were studied.
Anti-epilepsy medicine is also used for the treatment of other diseases such as migraine and bipolar disorder. The study shows that there were no differences relating to whether the women who used anti-epilepsy medicine during pregnancy were diagnosed with epilepsy or not.
Background for the results
Type of study: The population study was carried out using the Danish registers for the period 1997-2013.
The analyses takes into account differences in the child’s gender and date of birth, as well as the mother’s age, family situation, income, level of education, as well as any mental illness, use of psychiatric medicine and insulin, and substance abuse.
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To provide a systematic overview of interventions for stroke related visual impairments.
A systematic review of the literature was conducted including randomized controlled trials, controlled trials, cohort studies, observational studies, systematic reviews, and retrospective medical note reviews. All languages were included and translation obtained. This review covers adult participants (aged 18 years or over) diagnosed with a visual impairment as a direct cause of a stroke. Studies which included mixed populations were included if over 50% of the participants had a diagnosis of stroke and were discussed separately. We searched scholarly online resources and hand searched articles and registers of published, unpublished, and ongoing trials. Search terms included a variety of MESH terms and alternatives in relation to stroke and visual conditions. Article selection was performed by two authors independently. Data were extracted by one author and verified by a second. The quality of the evidence and risk of bias was assessed using appropriate tools dependant on the type of article.
Forty-nine articles (4142 subjects) were included in the review, including an overview of four Cochrane systematic reviews. Interventions appraised included those for visual field loss, ocular motility deficits, reduced central vision, and visual perceptual deficits.
Further high quality randomized controlled trials are required to determine the effectiveness of interventions for treating post-stroke visual impairments. For interventions which are used in practice but do not yet have an evidence base in the literature, it is imperative that these treatments be addressed and evaluated in future studies.
Visual impairments following stroke may include abnormalities of central and/or peripheral vision, eye movements and a variety of visual perception problems such as inattention and agnosia. The visual problems (types of visual impairment) can be complex including ocular as well as cortical damage (Jones & Shinton, 2006; Rowe et al., 2009a). Visual impairments can have wide reaching implications on daily living, independence, and quality of life. Links with depression have also been documented in the literature (Granger, Cotter, Hamilton, & Fiedler, 1993; Nelles et al., 2001; Ramrattan et al., 2001; Tsai et al., 2003; West et al., 2002). The estimation of the overall prevalence of visual impairment is approximately 60% at the acute stage following stroke (Ali et al., 2013; Barrett et al., 2007; Clisby, 1995; Freeman & Rudge, 1987; Isaeff, Wallar, & Duncan, 1974; Rowe et al., 2009b; Rowe et al., 2013). A review of the individual prevalence figures and the recovery rates for each of the possible post-stroke visual impairments has been reported elsewhere in the literature (Hepworth et al., 2016).
In order to treat and manage visual impairments caused by stroke it is important to establish the range and effectiveness of the available treatment options. The aim of this literature review is to provide a comprehensive synthesis of the evidence relating to treatment of visual problems after stroke.
The use of non-invasive brain neurostimulation (NIBS) techniques to treat neurological or psychiatric diseases is currently under development. Fatigue is a commonly observed symptom in the field of potentially treatable pathologies by NIBS, yet very little data has been published regarding its treatment. We conducted a review of the literature until the end of February 2017 to analyze all the studies that reported a clinical assessment of the effects of NIBS techniques on fatigue. We have limited our analysis to repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS). We found only 15 studies on this subject, including 8 tDCS studies and 7 rTMS studies. Of the tDCS studies, 6 concerned patients with multiple sclerosis while 6 rTMS studies concerned fibromyalgia or chronic fatigue syndrome. The remaining 3 studies included patients with post-polio syndrome, Parkinson’s disease and amyotrophic lateral sclerosis. Three cortical regions were targeted: the primary sensorimotor cortex, the dorsolateral prefrontal cortex and the posterior parietal cortex. In all cases, tDCS protocols were performed according to a bipolar montage with the anode over the cortical target. On the other hand, rTMS protocols consisted of either high-frequency phasic stimulation or low-frequency tonic stimulation. The results available to date are still too few, partial and heterogeneous as to the methods applied, the clinical profile of the patients and the variables studied (different fatigue scores) in order to draw any conclusion. However, the effects obtained, especially in multiple sclerosis and fibromyalgia, are really carriers of therapeutic hope.
In this paper, we present the combination of our soft supernumerary robotic finger i.e. Soft-SixthFinger with a commercially available zero gravity arm support, the SaeboMAS. The overall proposed system can provide the needed assistance during paretic upper limb rehabilitation involving both grasping and arm mobility to solve task-oriented activities. The Soft-SixthFinger is a wearable robotic supernumerary finger designed to be used as an active assistive device by post stroke patients to compensate the paretic hand grasp. The device works jointly with the paretic hand/arm to grasp an object similarly to the two parts of a robotic gripper. The SaeboMAS is a commercially available mobile arm support to neutralize gravity effects on the paretic arm specifically designed to facilitate and challenge the weakened shoulder muscles during functional tasks. The proposed system has been designed to be used during the rehabilitation phase when the arm is potentially able to recover its functionality, but the hand is still not able to perform a grasp due to the lack of an efficient thumb opposition. The overall system also act as a motivation tool for the patients to perform task-oriented rehabilitation activities.
With the aid of proposed system, the patient can closely simulate the desired motion with the non-functional arm for rehabilitation purposes, while performing a grasp with the help of the Soft-SixthFinger. As a pilot study we tested the proposed system with a chronic stroke patient to evaluate how the mobile arm support in conjunction with a robotic supernumerary finger can help in performing the tasks requiring the manipulation of grasped object through the paretic arm. In particular, we performed the Frenchay Arm Test (FAT) and Box and Block Test (BBT). The proposed system successfully enabled the patient to complete tasks which were previously impossible to perform.
The present study investigated the effects of anodal transcranial direct current stimulation (tDCS) on lower extremity muscle strength training in 24 healthy participants. In this triple-blind, sham-controlled study, participants were randomly allocated to the anodal tDCS plus muscle strength training (anodal tDCS) group or sham tDCS plus muscle strength training (sham tDCS) group. Anodal tDCS (2 mA) was applied to the primary motor cortex of the lower extremity during muscle strength training of the knee extensors and flexors. Training was conducted once every 3 days for 3 weeks (7 sessions). Knee extensor and flexor peak torques were evaluated before and after the 3 weeks of training. After the 3-week intervention, peak torques of knee extension and flexion changed from 155.9 to 191.1 Nm and from 81.5 to 93.1 Nm in the anodal tDCS group. Peak torques changed from 164.1 to 194.8 Nm on extension and from 78.0 to 85.6 Nm on flexion in the sham tDCS group. In both groups, peak torques of knee extension and flexion significantly increased after the intervention, with no significant difference between the anodal tDCS and sham tDCS groups. In conclusion, although the administration of eccentric training increased knee extensor and flexor peak torques, anodal tDCS did not enhance the effects of lower extremity muscle strength training in healthy individuals. The present null results have crucial implications for selecting optimal stimulation parameters for clinical trials.
Transcranial direct current stimulation (tDCS) is a non-invasive cortical stimulation procedure in which weak direct currents polarize target brain regions (Nitsche and Paulus, 2000). The application of anodal tDCS to the primary motor cortex of the lower extremity transiently increases corticospinal excitability in healthy individuals (Jeffery et al., 2007; Tatemoto et al., 2013) and improves motor function in healthy individuals and patients with stroke (Tanaka et al., 2009, 2011; Madhavan et al., 2011; Sriraman et al., 2014; Chang et al., 2015; Montenegro et al., 2015, 2016; Angius et al., 2016; Washabaugh et al., 2016). Thus, anodal tDCS has a potential to become a new adjunct therapeutic strategy for the rehabilitation of leg motor function and locomotion following a stroke.
Lower leg muscle strength is an important motor function required for patients who have had a stroke to regain activities of daily living (ADL). Lower leg muscle strength correlates with performance in activities, including sit-to-stand, gait, and stair ascent (Bohannon, 2007). Furthermore, lower leg muscle strength training increases muscle strength and improves ADL in patients with stroke (Ada et al., 2006). Therefore, lower leg muscle strength training is one of the important activities rehabilitating patients with stroke to regain their independence in ADL.
Several studies have examined the effect of a single session of tDCS on lower leg muscle strength, although the evidence is inconsistent (Tanaka et al., 2009, 2011; Montenegro et al., 2015, 2016; Angius et al., 2016; Washabaugh et al., 2016). Its effects seem dependent on tDCS protocols, training tasks, muscle groups, and subject populations. Although, most tDCS studies on lower leg muscle strength have focused on the acute effects of a single tDCS application, to the best of our knowledge, no study has examined how lower extremity strength training combined with repeated sessions of tDCS affects lower leg muscle strength. This type of investigation has strong clinical implications for the application of tDCS in rehabilitation for patients with lower leg muscle weakness.
Thus, to examine whether anodal tDCS can enhance the effects of lower extremity muscle strength training, the present study simultaneously applied anodal tDCS and lower extremity muscle strength training to healthy individuals and evaluated their effects on lower extremity muscle strength.
Continue —> Frontiers | Transcranial Direct Current Stimulation Does Not Affect Lower Extremity Muscle Strength Training in Healthy Individuals: A Triple-Blind, Sham-Controlled Study | Perception Science
Feeding and drinking are Activities of Daily Living which can be used to assess the motor control and functional ability of the upper limb. This paper presents the upper-limb kinematics during the execution of feeding and drinking activities, such analysis consisted in the measurement of angles of flexion for trunk and arm. Eight healthy subjects performed these activities in a simulated-environment while they were video recorded. Markers on anatomical landmarks were used to analyze the kinematics of the upper limb in the sagittal plane. Additionally an electro-hydraulic sensor was attached to each upper limb to assess the vertical position of the wrist relative to the shoulder. Results showed a difference on the angles of the elbow and trunk. The electro-hydraulic sensor showed to be an efficient way to record the vertical position of wrist.