Dear Movement Disorder Specialist,

I would like to draw your attention to a rather remarkable medical phenomenon which we have been witnessing and studying in recent years.

I’ve witnessed a significant improvement in the walking abilities of patients with movement disorders (including PD, MS, stroke, CP and senile gait) achieved through training with visual and auditory sensory feedback provided by a virtual reality device. This may not come as a complete surprise as there have been numerous reports in the medical literature about the linkage between gait and sensory inputs. Yet, I find that beside the understandable natural reluctance to embrace alternative approaches, there are also some misconceptions about how this approach works and whether it’s effective.

Some critical observations made during our clinical studies should help to clarify this issue.

The first reported observations using visual feedback (Martin, 1967) involved natural feedback cues, such as equally spaced transverse lines drawn on the ground. The early attempts to produce such cues by artificial means via technology used an "open loop" approach. This early device displayed transverse lines projected on a head-mounted display and moved at a constant speed regardless of the patient's motion.

Tests showed these "open-loop" visual cues had positive effects on gait in some patients, but their unnatural dynamics caused by imposing constant speed, compromised patient's safety, comfort, and performance, even causing freezing in some PD patients. This consequently reduced the patients’ willingness to continue using the approach and participate in further trials. ƒdoeds

On the other hand, patients participating in studies utilizing the latest virtual reality device report feeling safe and comfortable while experiencing the natural visual and auditory feedback it produces based on its measurement of their own body motion.

The safety and comfort that comes with natural visual and auditory feedback can only be produced by a closed-loop system using technology now known as "virtual reality". Although some people mistakenly included “open-loop” sensory signals under the virtual reality name-tag, only closed loop systems should be labeled “virtual reality”.

Indeed, virtual reality feedback is considerably more difficult to produce than rhythmic auditory cues or constant velocity visual cues, and it constitutes the only way to achieve an effect similar to the "natural" one. Moreover, the virtual reality devices available now make the "natural" effect more pronounced for training purposes, by bringing the feedback sensory signals closer to the patients own sensors – the eyes and the ears. In addition, unlike markings on the ground or an “open loop” system, the visual cues produced by the latest closed loop system are always aligned with the patient. That means each visual cue is perfectly placed in front of the patient’s next step even if he changes his step size, speed, direction, or even if he stumbles. Better yet, because the newest device resembles a cell phone in size and weight, patients can take it anywhere and practice at their convenience.

The geometry of the visual feedback cues also makes a big difference. The glide-symmetry of the human locomotion system must be matched by glide-symmetry in the visual cues. In our early trials, the virtual reality device displayed transverse lines without distinct symmetry. We then changed the display to a checkerboard tile arrangement more closely matching human glide-symmetry.

The difference proved astonishing: gait improvement, specifically walking speed and stride length, was about three times as high after training with the glide-symmetric cue than with the cue having no distinct symmetry. Needless to say, in our later trials we used the checkerboard tile option exclusively. It is now standardized in our latest device.

A lasting improvement in gait can only be achieved through persistent training, although some improvement is noticed in about half the patients walking while wearing the device for the first time. The other half don't show any improvement during their first use, and some even show a slight deterioration in initial performance. Unfortunately, noticing this phenomenon some of our early collaborators were too quick to give up. Fortunately, some leading movement disorders specialists persisted, and the results of their clinical studies are now published in the leading medical journals. Most importantly, primarily because of word of mouth, many patients have relentlessly asked to participate in the medical tests and to own a device, so that they can train at home.

During our studies, we found a stronger and lasting residual effect appears after training with the device for a few weeks. A training period of two to three weeks at home produces the best results. Training should also be kept fun, not made into work. The patient should take as many rests as desired, for as long as desired.

A case in point; the son of one of the patients who acquired the device for his father reported his father enthusiastically trained with the device at home every day for several weeks and showed substantial progress. Then the son called us saying his father got tired of the device and not only stopped showing progress, he even started retreating from his earlier improvement. We told him to have his father take a break from his training. "How long?" asked the son? "For as long as he feels like", we replied, "He should only restart his training when he really wants to". A few weeks later, the son called again. His father went back to training with the device, and now his freezing episodes are completely gone and he is walking normally even when he’s not wearing the device.

Presently, in our clinical testing, we hardly pay any attention to "on-line improvement" anymore. It’s the residual, lasting effect we are looking for. We compare after-training performance to baseline performance.

It took us twelve years to develop, test, and bring to market the US-patented GaitAid virtual reality device. Patients who’ve already acquired the device have written us numerous thank-you letters telling us how the device has changed their lives. You can find their testimonials on our website. Numerous clinical trials show the device’s effectiveness as well.

If you would like more information please fill out the form below.

With best wishes,

Prof. Yoram Baram
Roy Matas / Winnipeg Chair in Biomedical Engineering
Computer Science Department
Technion, Israel Institute of Technology
Haifa, 32000
Israel
Phone: +972-4-8294266
Fax: +972-4-8293900
Email: baram@cs.technion.ac.il
Web site: www.cs.technion.ac.il/~baram
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