Posts Tagged noninvasive
[WEB PAGE] The Use of Noninvasive Brain Stimulation, Specifically Transcranial Direct Current Stimulation After Stroke
Motor impairment is a leading cause of disability after stroke. Approaches such as noninvasive brain stimulation are being investigated to attempt to increase effectiveness of stroke rehabilitation interventions. There are several types of noninvasive brain stimulation: repetitive transcranial magnetic stimulation, transcranial direct stimulation (tDCS), transcranial alternative current stimulation, and transcranial pulsed ultrasound to name a few. Of the types of noninvasive brain stimulation, repetitive transcranial magnetic stimulation and tDCS have been most extensively tested to modulate brain activity and potentially behavior. These two techniques have distinctive modes of action. Repetitive transcranial magnetic stimulation directly stimulates neurons in the brain and, given the appropriate conditions, leads to new action potentials. On the other hand, tDCS polarizes neuronal tissue including neurons and glia modulating ongoing firing patterns. There are also differences in cost, utility, and knowledge skill required to apply tDCS and repetitive transcranial magnetic stimulation. Transcranial direct stimulation is relatively inexpensive, easy to administer, portable, and may be applied while undergoing therapy, with lasting excitability changes detectable up to 90 minutes after administration. Repetitive transcranial magnetic stimulation equipment is bulkier, expensive, technically more challenging, and a patient’s head must remain still when treatment is being applied therefore needs to be administered before or after a session of rehabilitation. Because of these differences, tDCS has been more accessible and has rapidly grew as a potential tool to be used in neurorehabilitation to facilitate retraining of activities of daily living (ADL) capacity and possibly to improve restoration of neurological function after stroke.
There are three current stimulation approaches using tDCS to modulate corticomotor regions after stroke. In anodal stimulation mode, the anode electrode is placed over the lesioned brain area and a reference electrode is applied over the contralateral orbitofrontal cortex. Anodal tDCS is placed over the ipsilesional hemisphere to improve the responses of perilesional areas to training protocols. In cathodal stimulation, the cathode electrode is placed over the nonlesioned brain area and reference electrode over the contralateral (ipsilesional) orbitofrontal cortex. This approach has been predicated on the hypothesis that the nonstroke hemisphere will be inhibited by tDCS resulting in an increased activation of the ipsilesional hemisphere due to rebalancing of a presumably abnormal interhemispheric interaction. Although some studies have shown this approach to be beneficial, the causative role of interhemispheric interaction imbalance has been recently challenged and refuted.1 Thus, if cathodal stimulation approaches are beneficial, the behavioral effect cannot be explained by a presumed correction of abnormal interhemispheric connectivity. Finally, dual tDCS approach involves simultaneous application of the anode over the ipsilesional and the cathode over the contralesional side. Here again, the intended mechanism of action is to rebalance the presumably abnormal interhemispheric interaction.
CLINICAL QUESTIONS ADDRESSED
What is the best tDCS type and electrical configuration? What are the effects of tDCS with rehabilitation program for upper limb recovery after stroke?
RESEARCH FINDINGS OF tDCS
This short article discusses data obtained from a network meta-analysis of randomized controlled trials and a recent meta-analysis. The network meta-analysis included 12 randomized controlled trials including 284 participants examining the effect of tDCS on ADL function in the acute, subacute, and chronic phases after stroke.2 The meta-analysis included 9 studies with 371 participants in any stage after stroke.3
The network meta-analysis found evidence of a significant moderate effect in favor of cathodal tDCS without significant effects of dual tDCS, anodal tDCS, or sham tDCS. There was no difference in safety (as assessed by dropouts and adverse events) between sham tDCS, physical rehabilitation, cathodal tDCS, dual tDCS, and anodal tDCS. Elsner in a previous review of tDCS in 2016 found an effect on improving ADL, as well as function of the arm and lower limb, muscle strength, and cognition. Thus, the findings from the most recent meta-analysis indicating cathodal that tDCS improves ADL capacity are in line with previous meta-analyses. Of note, there was no evidence of an effect of either cathodal or other tDCS stimulation approaches on upper paretic limb impairment after stroke as measured by the Fugl-Meyer scale.
A meta-analysis that included participants in any stage after the stroke showed that tDCS in conjunction with multiple sessions of rehabilitation had no significant effect over delivering therapy alone for upper limb impairment and activity after stroke. This negative finding might be due to patient’s being in an acute, subacute, or chronic stage after stroke as well as variations in the type of therapy performed paired with tDCS (ie, conventional vs. constraint-induced movement therapy vs. robot protocol).
RECOMMENDATIONS FOR PHYSIATRIC PRACTICE
There seems to be a modest effect supporting the use of tDCS as a co-adjuvant of rehabilitation interventions to improve ADLs after stroke. Cathodal tDCS seems to be the most promising approach, especially when applied early after the stroke. However, the evidence remains preliminary and does not warrant a widespread change in clinical rehabilitation practice at this time.
There is no evidence supporting the use of tDCS to improve motor impairment (as measured by the FMS) at this point.
Importantly, tDCS remains as a very safe intervention, with no differences in safety when real vs. control tDCS is applied.
A new meta-analysis of existing studies shows that a technique called repetitive transcranial magnetic stimulation might be a useful tool to help stroke survivors regain the ability to walk independently.
Repetitive transcranial magnetic stimulation (rTMS) is a noninvasive brain stimulation technique; magnetic coils are placed on a person’s scalp, and short electromagnetic pulses are delivered to specific brain areas through the coil.
Although these pulses only cause an almost imperceptible “knocking or tapping” sensation for the patient undergoing the procedure, they reach into the brain, triggering electric currents that stimulate neurons.
rTMS has mainly been used to treat psychosis, depression, anxiety, and other mood disorders with a fair degree of success. In a recent study, more than one third of people living with auditory verbal hallucinations — a marker of schizophrenia — reported a reduction in their symptoms following the procedure.
But researchers have also been delving into the potential that the technique has for improving life after stroke. Four years ago, for instance, a team of researchers at The Ohio State University Wexner Medical Center in Columbus used rTMS to improve arm movement in people who had experienced a stroke, and more studies have explored this therapeutic potential since.
Now, a team of researchers — jointly led by Dr. Chengqi He, of Sichuan University in the People’s Republic of China, and Shasha Li, of Massachusetts General Hospital and Harvard Medical School, both in Boston, MA — set out to review these studies.
Dr. He and colleagues wanted to see if the technique improved motor skills for people who had stroke; to do so, the researchers examined the impact rTMS has on walking speed, balance, and other key factors for post-stroke rehabilitation.
The findings were published in the American Journal of Physical Medicine & Rehabilitation, the official journal of the Association of Academic Physiatrists.
rTMS ‘significantly improves walking speed’
Dr. He and team reviewed nine studies of rTMS — including five randomized controlled trials — which were published between 2012 and 2017.
The people who participated in these studies had either had an ischemic stroke — that is, a stroke caused by a blood clot in one of the brain’s arteries — or a hemorrhagic stroke — that is, one caused by bleeding within the brain.
Of the nine studies, six included data on the walking speed of 139 stroke survivors. The researchers carried out a pooled analysis of these studies, and the results revealed that rTMS “significantly improves walking speed.”
This improvement was greater among people who received stimulation on the same side of the brain that the stroke occurred. By contrast, those who received rTMS on the opposite side did not see any improvement.
Other key health outcomes for stroke survivors such as balance, motor function, or brain responsiveness did not show any improvement as a result of rTMS.
In the United States, it is estimated that almost 800,000 people annually have a stroke, which makes the condition a leading cause of long-term disability in the country. More than half of the seniors who survived a stroke have reduced mobility as a result.
Although the review shows that rTMS is a promising strategy for restoring independent walking, the authors say that more research is needed. Dr. He and colleagues conclude:
“Future studies with larger sample sizes and an adequate follow-up period are required to further investigate the effects of rTMS on lower limb function and its relationship with changes in cortical excitability with the help of functional neuroimaging techniques.”
[BLOG POST] Brain Computer Interfaces (That Translate Human Thought To Direct Action): Their Evolution And Future
In the last few years, we have read quite a bit about how technology has allowed our brain to control devices or objects around us without the use of limbs. (If you haven’t, you can read about some examples here, here, and here). Futurism.com, a great website that posts about how human potential can be maximized, has this infographic that explains the basics of Brain Computer Interfaces – the use of technology to translate human thoughts into machine commands. We are seeing the use of BCI more and more with prosthetic limbs but where does it end? Will we able to upload our memories straight from our brain to the cloud in the future? Sky is the limit when it comes to innovation through technology.
Read this infographic to know the types of Brain-Computer Interfaces, their origin, what they have in store for us in the future, and how they can bridge the gap between disabled and able-bodied. Text version of infographic is right below the image.
Imagine a world where machines can be controlled by thought alone. This is the promise of brain-computer interfaces (BCIs) – using computers to decode and translate human thoughts into machine commands. Here’s a look at the evolution of BCI technology, its current state, and future prospects.
Invasive: Signal-transmitting devices are implanted directly in the brain’s gray matter. This method produces the highest quality signals, but scar tissue build up can cause signal degradation.
Partially Invasive: Devices are implanted within the skull but not within the brain tissues. Produce higher quality signals than noninvasive techniques by circumventing the skull’s dampening effect on transmissions, and has less risk of scar tissue buildup.
Noninvasive: Involves simple wearables that register the EM transmissions of neurons, with no expensive or dangerous surgery needed. This technique is certainly easier, but suffers from poor resolution caused by the skull’s interference with signals.
A Short History of BCI
1924: German neuroscientist Hans Berger discovers neuroelectrical activity using electroencephalography (EEG).
1970: The Defense Advanced Research Projects Agency (DARPA) begins to explore the potential BCI applications of EEG technology.
1998: First brain implant produces high quality signals.
2005: A monkey’s brain is successfully used to control a robotic arm.
2014: Direct brain-to-brain communication achieved by transmitting EEG signals over the internet.
Types of Noninvasive BCI
- Eye movement and pupil size oscillation
- Magnetic resonance imaging and magnetoencephalography
Applications of BCI
- Direct mental control of prosthetic limbs.
- Neurogaming – interaction within video game and virtual reality environments without the need for clumsy interface.
- Synthetic telepathy – the establishment of a direct mental connection or communications pathway between minds.
- The use of BCI in tele-robotics will allow human operators to directly “link” with robotic machines. – granting us a new way to explore aliens worlds, handle dangerous materials, and perform remote surgery.
- A wealth of new possibilities for interfacing with computers opens up – including linking to the internet, uploading memories to the cloud, etc.
It will effectively erase the divide between the disabled and the able-bodied.
National Academy of Engineering, Techradar, Brain Vision UK, PLOS ONE
This infographic was originally posted on futurism.com.
Transcranial magnetic stimulation (TMS) is a noninvasive procedure that uses magnetic fields to stimulate nerve cells in the brain to improve symptoms of depression. TMS is typically used when other depression treatments haven’t been effective.
How it works
During a TMS session, an electromagnetic coil is placed against your scalp near your forehead. The electromagnet painlessly delivers a magnetic pulse that stimulates nerve cells in the region of your brain involved in mood control and depression. And it may activate regions of the brain that have decreased activity in people with depression.
Though the biology of why rTMS works isn’t completely understood, the stimulation appears to affect how this part of the brain is working, which in turn seems to ease depression symptoms and improve mood.
Treatment for depression involves delivering repetitive magnetic pulses, so it’s called repetitive TMS or rTMS.
Spasticity, Second Edition: Diagnosis and Management
Allison Brashear, MD
[ARTICLE] The feasibility of a brain-computer interface functional electrical stimulation system for the restoration of overground walking after paraplegia – Full text HTML
Background: Direct brain control of overground walking in those with paraplegia due to spinal cord injury (SCI) has not been achieved. Invasive brain-computer interfaces (BCIs) may provide a permanent solution to this problem by directly linking the brain to lower extremity prostheses. To justify the pursuit of such invasive systems, the feasibility of BCI controlled overground walking should first be established in a noninvasive manner. To accomplish this goal, we developed an electroencephalogram (EEG)-based BCI to control a functional electrical stimulation (FES) system for overground walking and assessed its performance in an individual with paraplegia due to SCI.
Methods: An individual with SCI (T6 AIS B) was recruited for the study and was trained to operate an EEG-based BCI system using an attempted walking/idling control strategy. He also underwent muscle reconditioning to facilitate standing and overground walking with a commercial FES system. Subsequently, the BCI and FES systems were integrated and the participant engaged in several real-time walking tests using the BCI-FES system. This was done in both a suspended, off-the-ground condition, and an overground walking condition. BCI states, gyroscope, laser distance meter, and video recording data were used to assess the BCI performance.
Results: During the course of 19 weeks, the participant performed 30 real-time, BCI-FES controlled overground walking tests, and demonstrated the ability to purposefully operate the BCI-FES system by following verbal cues. Based on the comparison between the ground truth and decoded BCI states, he achieved information transfer rates >3 bit/s and correlations >0.9. No adverse events directly related to the study were observed.
Conclusion: This proof-of-concept study demonstrates for the first time that restoring brain-controlled overground walking after paraplegia due to SCI is feasible. Further studies are warranted to establish the generalizability of these results in a population of individuals with paraplegia due to SCI. If this noninvasive system is successfully tested in population studies, the pursuit of permanent, invasive BCI walking prostheses may be justified. In addition, a simplified version of the current system may be explored as a noninvasive neurorehabilitative therapy in those with incomplete motor SCI.
[REVIEW] Transcranial Direct Current Stimulation: From Basic Research on Psychological Processes to Rehabilitation – Full Text PDF
Transcranial direct current stimulation (tDCS) is an “old/new” noninvasive brain modulation technique that has gained increasing popularity and relevance in psychology and neuroscience. The contemporary tDCS procedure is effective and painless. It was shown to modulate motor performance and several sensory and cognitive functions. It can be used to study cortical organization and clarify brain-behavior relationships.
Using tDCS for rehabilitation is a promising strategy, and numerous publications suggest that it can be used alone or combined to augment the outcomes of behavioral training and pharmacological interventions. Compared with other brain modulation techniques, it has the advantage of being noninvasive and safe, with easy and effective placebo controls. Its efficacy, low cost, and ease of use make tDCS a very convenient tool for researchers in developing countries.
This review introduces tDCS to a new audience and seeks to inspire future investigations in the field. We highlight work that illustrates the main concepts and applications of tDCS as a basic research and rehabilitation tool.