Timothy C. Hain, MD of Chicago Dizziness and Hearing. If you have questions about this treatment, you can email firstname.lastname@example.org.
Page last modified: April 11, 2017
Mal de Debarquement syndrome (MDDs) is a motion sickness variant that mainly occurs after prolonged motion on a cruise (Hain et al, 1999; Hain and Helminski, 2014). Medical treatment is very limited, but there has recently been a new procedure reported to be helpful.
We duplicated the protocol of Dai et al (2014) to treat Mal de Debarquement Syndrome. They reported cure or substantial improvement of 70% of 24 individuals treated, and more recently about 60% improvement in a much larger number of subjects.
|Video Wall at Chicago Dizziness and Hearing||Treatment Paradigm (From Dai et al, 2014).|
We have built a "video wall" consisting of 4 very large televisions (upper left), and we wrote software to duplicate the treatment protocol described by Dai et al (upper right). This is offered through our physical therapy treatment program. An example of the optokinetic stimulus is shown above and also can be seen through the software link above.
Our system largely duplicates the protocol of Dai et al (2014). This is not a research or study protocol -- this is a treatment protocol for dizziness using habituation, similar to other treatments used for visual dependence. We think that this procedure works through the "pseudocoriolis effect" (Dichgans and Brandt; 1973; Grabiel et al; 1969). In essence, the idea is that the OKN stimulus builds up a "bias" in the motion sensing machinery in the brainstem interpreted as rotation about earth vertical, and the roll head movement causes a conflict to occur because when the head tilts, the visual surround does not tilt as well.
Prior to treatment, we measure symptoms using the simulator symptom questionnaire (SSQ). There are 5 treatments/day for 5 days in a row, again checking on progress each day with another SSQ. We encourage patients to stay in a local hotel, to avoid "undoing" the treatment. It is important to "batch" treatments -- and for this reason we schedule them to all occur in a single week.
Patients have to stop taking certain medications that might block adaptation -- such as benzodiazepine medications (e.g. klonazepam, diazepam (Valium), alprazolam (Xanax), lorazepam (Ativan)), vestibular suppressents (e.g. meclizine), for at least 2 weeks prior to starting the treatment protocol. If patients fly back home after the protocol, we will arrange for them to take klonazepam at the beginning of the trip back.
|Computerized Dynamic Posturography to measure sway.||Dr. Hain performing the Fukuda Stepping Test (Fukuda, 1984)|
1. All patients have an initial evaluation by our vestibular physical therapist. They also see a CDH physician, generally Dr. Cherchi, if they have not already done so. We rarely treat patients who do not fit the usual criteria for MDDs (e.g. Hain and Cherchi, 2016) or patients who have not had MDDs for at least 3 months. We will do this if the patient and their doctor understand that they are not a good fit but wish to proceed in any case.
a. Severity of MDDs will be measured using the SSQ.
b. The physical therapist will measure rocking frequency using posturography. While Dai et al used a "Nintendo Wii" to measure postural sway, we use a standard computerized posturography system (see above)
c. Video-oculography is to determine if the subject has vertical nystagmus elicited by rolling of the head at the frequency found in step 1. If, slow-phase velocity is upward with head to the right, and downward with head to the left, we will use an optokinetic stimulus to the left. Otherwise we will use one to the right (see figure from Dai et al. above). This is not our preferred method at this writing (April, 2017), as we find it difficult to detect the vertical nystagmus, and distinguish it from cross-coupling from technical factors. Because of this, we prefer to use method 'd'.
d. The Fukuda stepping test (see above, also Fukuda 1984) is used to determine the optokinetic stimulus direction. This is a procedure that involves stepping in place, with eyes closed, on a mat for 30 seconds. The amount of rotation is determined from the rotation in place. This is our favored method at this writing.
e. Should the daily SSQ scores appear to be worsening rather than improving, or just not changing at all, we switch the direction at mid week (i.e start of third day of treatment). This is extremely rare, because most patients have improved substantially between day 1 and 2 (see graph below).
2. Patients are seated in front of the optokinetic array shown above. The stripes are rotated at constant velocity (initially 5 deg/sec), while the head is rolled +- 20 deg at their rocking frequency. A metronome is used to set the rocking frequency (typical 1/2 Hz). One click/second, combined with the head going to either side, corresponds to 1/2 hz. There are 4 sessions/day (or more) for 5 days.
3. After treatment is finished, posturography is repeated to measure changes in body sway and rocking.
4. Patients are sent home with a home OKN task. This link describes the use of a web program that provides the same OKN stimulus as used in the office, but of course using a smaller screen and possibly less capable graphics hardware.
|Treatment results in first 27 patients (less is better).|
Above is the average score of the simulator sickness questionnaire results in the 27 patients treated so far. There was a large drop in symptoms between day 1 and day 2 (i.e. after the first day of treatment), and a gradual improvement over subsequent days. Of course, this is not a "controlled study", just reporting of results.
We are encouraged by the general improvement, but there are some important points. First, this process seems to reflect more of a gradual process rather than a "quick fix". While some people do better than others, we are not seeing patients going from symptomatic to completely normal as a general rule (actually this did happen once). This fits in with our idea that what is working here is habituation due to cross-axis visual/vestibular stimulation. If this idea is correct, it may not matter which way the stripes are going, or whether the head roll frequency is precise, but rather it may mostly matter how much time is spent on this task, and also if the visual stimulus is "compelling", and creates an illusion that the person is moving.
Treatment results in first 27 patients (more is better, 70 is normal, 100 is perfect).
Regarding posturography results, pre (before day 1) and post (end of day 5) were obtained in 25 subjects. The average score prior to treatment was 61.3, and after treatment, 72.1. Normal persons generally score about 70, and thus the change of 11 is roughly a 15% improvement, and furthermore, patients are "normal" on average when they finish. The track record here is more erratic than with the SSQ. There were many subjects whose posturography did not budge at all, and even one patient where the score went slightly down (from 35 to 33).
Regarding long term results, we have SSQ data from 18 patients at week 2. The average SSQ was 8.9 (which is almost identical to the result at the end of the treatment week), but better than the pre-treatment average of 14.4. Our interpretation of this result is that the intensive exposure in the clinic seems to improve symptoms and balance, but either the improvement has "plateaued" or the home program is not as "strong" as the in-clinic. At this writing, we are just not sure, but would we would tend more to towards the idea that improvement has plateaued. Or to put this into other terms, if someone has an injury, and you have them exercise, you can improve their overall situation, but not necessarily restore them to normal.
It may be that habituation about other axes - -such as with vertical OKN, or perhaps with an "umbrella" type visual stimulus while moving the head up/down or side-side, would be reasonable to add to persons who have "maxed out" benefit on the horizontal paradigm. The PT literature calls increasing the difficulty of an exercise once a simpler one is mastered, "progression". This is unexplored territory and more data is needed.