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Regaining Strength After StrokeTailwind featured in Discoveries + Breakthroughs - 05/01/2011 Regaining Strength After Stroke Read the article »

Scientific Development of the Tailwind Device

More than 780,000 Americans suffer a stroke each year, and over half will experience some paralysis. Encore Path has developed a solution to help improve arm function and range of motion for people with stroke or other brain injury. Published clinical studies demonstrate that stroke survivors with moderate paralysis improved their arm function when using the Tailwind device. Tailwind, formerly known as the Bilateral Arm Trainer with Rhythmic Auditory Cueing, or BATRAC, is patented in the US, Europe and Canada. The Tailwind is:

  • Proven effective in published clinical studies
  • Can be used by patients in their own homes
  • Is the most cost effective solution for arm paralysis on the market today
  • Will restore a significant quality of life for thousands of stroke patients

The Tailwind device

The Tailwind’s primary medical innovation is controlling the independent movement of the arms by reactivating central neuromuscular pathways.  Dormant pathways are reactivated after repetitive training on Tailwind.  Evidence of motor cortex activation after training has been documented in scientifically controlled studies, using functional magnetic resonance imaging (fMRI). There are no invasive components to this device. Tailwind requires the individual to move both arms (independently) along a resistance-free track. The movement must be initiated by the individual thus requiring neuromuscular control. Affected hands may be attached to the device with simple straps in order to facilitate movement for the more moderate to severely impaired individuals. After several 5 minute training sessions over a 6 week period, marked improvement in movement and function are noticeable in individuals as much as 20 years post-stroke. The key benefits to the stroke patient are:

  • Statistically significant improvement in functional motor performance
  • Changes in isometric strength
  • Wider range of motion
  • Ability to practice the therapy at home
  • Durable and lasting results

The Tailwind Inventors

Dr. Sandra McCombe Waller is currently involved in research as part of the Claude Pepper Center for Older Americans in Baltimore, with funding to study an innovative combination of bilateral and unilateral training to improve arm and hand function in patients with moderate severity paresis after brain injury. She also studies the underlying neural mechanisms associated with recovery of function with unilateral, bilateral and combination therapies using transcranial magnetic stimulation and functional magnetic resonance imaging.  She has collaborated the last 8 years with Dr. Jill Whitall in research involving bilateral arm training with rhythmic auditory cueing. Together they developed and patented a unique bilateral arm training device named the BATRAC.

Dr. Whitall has almost 20 years of experience in mentoring graduate students, at the University of Wisconsin, Madison, and at the University of Maryland, Baltimore. She has been or is currently primary or secondary advisor to 10 PhD students and 10 MS students. In addition, since arriving at the UMB, Dr. Whitall has supervised 5 research projects of physical therapy students. In the Department’s PhD program she is currently the primary advisor to three students. Dr. Whitall teaches the principles of motor control, learning, and motor development as they relate to rehabilitation. She trains her students to use and develop paradigms to assess motor coordination (e.g., a tapping apparatus; a gait mat; a reaching protocol) and methods of reducing/analyzing coordination data. In addition, she and her students are actively developing better methods of intervention for adults with stroke and children with movement problems.

Genesis of the BATRAC Idea

 At the time they began to develop the BATRAC, they had already completed a study looking at walking with stroke patients and using rhythmic auditory cues. The two were concerned with competing for subjects who were doing different tests with treadmills, a study associated with walking. Dr. McCombe Waller suggested they switch their focus to looking at upper extremity movement because at the time, there weren’t a lot of studies being done in this area. They also decided to use the same rhythmic auditory cueing as they had done previously with the walking trials. Using motor control principles, Drs. Whitall and McCombe Waller came up with two aspects that were important to include in a new training device they wanted to develop. One aspect was using both arms, but not having them linked, even though only one arm is affected with paresis in stroke survivors. They believed this “neuro-functional brain coupling” would yield better results than just training with one arm. The other aspect was to use in-phase and anti-phase patterning, because those are very stable patterns in motor control and they thought those would be the best ones to try first. The next task was to decide on how such a training device might look. Dr. Whitall noted that Dr. McCombe Waller was instrumental in determining how the handles might be designed, and they knew they needed it to be available for generalization so they could try different angles and other efforts such as having the patients push up against gravity. Once they determined the physical properties of the device, they employed a student who was working with them who also had carpentry experience to build with the first prototype, based on their description.

Different ideas

Dr. Whitall has said that while this was a completely new approach, they did have some clinical experience to rely on. Dr. McCombe Waller pointed out that from a research perspective, this was a completely new area. Forced use therapy was the main ideology being tried in the literature at the time, so they chose to be different.

Discarded ideas

One principal idea that was discarded was the issue of connecting the arms of the device to each other. Dr. McCombe Waller thought about using a bicycle, but discarded that idea because it did not allow patients to extend their arms all the way out. They considered whether they could use commercial equipment to do this but they found nothing applicable, so they decided to design something new. Anything that had the two arms connected, or yoked, that made the arms move in a circular bicycle movement was discarded because that did not offer the range of motion that was needed. Drs. Whitall and McCombe Waller considered several options because they knew what they wanted scientifically and clinically. The very first iteration was a device that held the patient’s body in place, while providing for a very active movement on the user’s part.

How does BATRAC work?

The early prototypes worked, because they could see improvements in the patients. Dr. McCombe Waller decided she wanted to make it work better. They began by modifying the training regimen. They recognized that the need to work the users harder was essential so they can progress. The patients had to reach out further, reach out faster, and reach up higher. Dr. Whitall also was careful to incorporate motor learning principles. When learning a new skill, she notes, there is a need to get the neural pathways going so they are able to become more automatic. Repetition is one aspect that helps it to work, but there were other things that had to be incorporated into the design, such as the neuro functional couplings. Because the arms are unyoked, no help is being given to the patient’s paretic arm by his unaffected arm. Drs. Whitall and McCombe Waller theorized that because the unaffected arm was working at the same time, it was going to help the paretic arm to also work a bit harder. It began with ideas about motor training, but they realized they had to find a way to get the patients to work harder. They did not change the speed of the movement, but they pushed patients to extend their arms farther out. With this, they saw evidence of motor function recovery — not just training the arms but changing the neuromuscular connection from the brain to the arms. Evidence of this was seen in fMRI studies.

Technical and Financial issues

Drs. Whitall and McCombe Waller received grant funding to build the first prototype. It was made of wood and was fairly primitive. The doctors provided the innovation and some of the resources themselves, and Dr. McCombe Waller trained patients how to use the device. The results from using this first prototype were enticing enough for them to be awarded another grant. That funding was used to make a next generation BATRAC prototype and hire people to train patients how to use it.  Parts wore out and broke down, and subsequent prototypes were designed to improve durability and weight.

New ideas on an original design

There are notable differences with the new Tailwind BATRAC. The handles are more comfortable for users, and the trunk constraint has been redesigned for patient comfort. The Tailwind is less than half the weight of the previous prototype, adding to its portability and ease of use.  In addition, the new Tailwind design can be folded for carrying and storage.

Research Experience

Dr. McCombe Waller received her Ph.D. from the University of Maryland Baltimore in 2004. She is a trained physical therapist. She graduated in 1985, and began conducting research in 1995. Dr. Whitall received her Ph.D. from the University of Maryland College Park in 1988. She began doing stroke research in 1990. A student project involving auditory cueing began their research collaboration.