The Bertec and Gyrostim devices -- unproven treatments for MdDS.

Timothy C. Hain, MD • Page last modified: September 24, 2022

Bertec has a MdDS protocol in their very cool looking balance device, dynamic CDP, as shown above(https://bertec.com/). This device appears to be basically a visual stimulator with a posture platform underneath it. It is probably better than the TV array (that we used in our clinic for a few years), or the OKN drum (used by Dr. Dai), as it is more "immersive" than our flat screen, and it does more axes (than the drum). We don't see why the posture platform is helpful. We were disturbed in interviewing an MdDS patient who told us that this device was being used for treatment (not very successful), using a 3 times/week 1 hour protocol. To us, this seems to be not enough. Our thought is that any "device" based treatment, that is successful, will take a lot of time (i.e. similar to the Dai protocol), and because it "locks down" both the patient and the room and the device, be very costly. We don't think there will be any one hour treatments and cures, or for that matter, series of 1 hour treatments 3 times/week for 8 weeks with cures. Still, time will tell. We hope to see some papers on the topic.

The "Gyrostim" device, above to the right, is a recent addition to the procedures advocated for treatment of MdDS. This device is mainly found in Chiropractic practices (Especially chiropractors who call themselves "functional neurologists"), as well as in a physical therapy practice in North Carolina. It is another cool looking device which resembles a carnival ride like the "tilt-a-whirl". While we are not sure about it's effectiveness or lack thereof, Gyrostim treatment is unencumbered by any scientific literature, aside from the following:

According to an email that I was sent on 6/13/2019, Dr. Kim Fox of AVORA health centers (Kim is a doctor of physical therapy) presented an abstract on treatment with the Gyrostim at the "International Congress on Motion Sickness", on July 2019. The Gyrostim protocol was called "SMART" training, for sensorimotor, multi-axis, rotational training, combined with "mindfullness breathing, relaxation and grounding" techniques. The abstract does not mention a placebo control and it is called a "retrospective chart review". So a rather low level of evidence, but at least there is a start.

Although the Gyrostim is just a device, it does seem to be used in some suspicious contexts, and we have more discussion about the Gyrostim device on our "fraud" page. Some of the MdDS patients who have been treated with the Gyrostim provided me with some comments about their experience. These are found here.

The Gyrostim resembles a ride we took once in an amusement park. It seems to do both Yaw and pitch. In other words, it is a "pitch while rotating" device (yaw is the rotating about the updown-axis of the head part). It doesn't seem to have any optokinetic component, although the subjects may do some visual tasks during the ride. The old literature on these stimuli suggests that pitch while rotating is very nauseating (Raphan et al, 1983; Raphan et al,1999) . Nevertheless, as the time that people report being "exposed" to the gyrostim is generally very short, about 60 seconds, perhaps this doesn't matter.

Our take on these is that anything that provides multi-axis visual-vestibular stimulation will probably habituate the vestibular system, and has a some chance of helping MdDS. Judging from previous literature about habituation, it is best to "batch" multiple sessions. The protocol used in the Dr. Dai treatment is 4 sessions/afternoon, with about 10-15 minutes of exposure each session. This seems pretty reasonable.

We would think the Gyrostim might also help MdDS if people were exposed to it for 10 minutes at a time, 4x/day, but the issue would be tolerability (i.e. vomiting), and also because this device looks pretty fancy, high cost.

From the reports we have been provided from patients that had Gyrostim exposure, it appears that the duration of rotation is actually about 30-60 seconds, and that this is provided for an undisclosed number of repetitions/hour. There isn't much detail given by the successful patients. Presumably the duration is short to avoid motion sickness. If there is only a few minutes of stimulation/hour, it is difficult to see how this works. It is well worked out in other literature that habituation takes a lot of time. Sort of a "no pain -- no gain". If it isn't habituation, how do these brief (?) exposures for 5 days, cure MdDS ? It is very puzzling.

Well given the claims of high efficacy, it should be very easy to prove that the Gyrostim works for MdDS. We would like to see the results of a series, on the Gyrostim device, including roughly 20 MdDS patients. It is difficult to see how one could provide a placebo control, and also difficult to see how one could find an objective outcome measure. Perhaps the time constant of a rotatory chair step response would work, as this has been used in older studies. But a good start would be just to do some before/after surveys on a group of people with well defined MdDS. We would not expect 100% success, but a general trend towards improvement might advance the field.

Neither of these devices combines multi-axis with visual stimulation. Combine Bertec with Gyrostim. So there is still room for more gadgets ! The military must have these things (they are called flight simulators).

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