Page last modified: March 2, 2021
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. This 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.
We duplicated their protocol, and used it for several years at CDH. We stopped doing this because the logistics were just too difficult. Nevertheless, this protocol is still offered by Dr. Dai, and perhaps other places in the country.
|Video Wall at Chicago Dizziness and Hearing||Treatment Paradigm (From Dai et al, 2014).|
This material is kept here in case someone else wishs to "clone" this approach. While we found the logistics challenging, this may not be the case for another situation. The logistics were difficult because this required us to train and dedicate a staff member and a room to this project for a half-day 5 days/week.
We 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 duplicated the protocol of Dai et al (2014). 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 measured 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 had to stop taking certain medications that might block adaptation -- such as benzodiazepine medications (e.g. clonazepam (Klonopin), diazepam (Valium), alprazolam (Xanax), lorazepam (Ativan)), vestibular suppressents (e.g. meclizine), for at least 2 weeks prior to starting the treatment protocol. Two weeks is chosen to be enough time for these drugs to leave the system. The half-life of some of these drugs can be as long as 3 days. This elimination of benzodiazepines also makes it sure that the medications themselves are not causing dizziness.
If patients flew back home after the protocol, we arranged for them to take halcion (triazolam, in the lowest dose) at the beginning of the trip back. The same goes for being driven home by someone else. Triazolam is a short acting drug (5 hours), of the same family as clonazepam. Of course, it is suggested that you do NOT drive yourself home on a medication that you have never taken before, and you should either have someone else drive you home, or not take this medication.
|Computerized Dynamic Posturography to measure sway.||Dr. Hain performing the Fukuda Stepping Test (Fukuda, 1984)|
1. All patients had an initial evaluation by a 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 was measured using the SSQ.
b. The physical therapist measured rocking frequency using posturography. While Dai et al used a "Nintendo Wii" to measure postural sway, we used a standard computerized posturography system (see above)
c. Video-oculography was 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 prefered 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 was rare, because most patients improved substantially between day 1 and 2 (see graph below).
2. Patients were seated in front of the optokinetic array shown above. The stripes were rotated at constant velocity (initially 5 deg/sec), while the head is rolled +- 20 deg at their rocking frequency. A metronome was used to set the rocking frequency (typically 1/4 Hz). We usually set the metronome for one click per second. If the head is gradually rolled to the right for 2 clicks, and then gradually to the left for two clicks, this is 1/4 hz. There were 4 sessions/day (or more) for 5 days.
3. After treatment is finished, posturography was repeated to measure changes in body sway and rocking.
4. Patients were sent home with a home OKN task.
|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 as of early 2018. 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). Note that 70 is just barely normal for most people.
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.
This treatment takes a lot of time, and costs quite a bit for both the patients and the clinic It seems to us that it would be more reasonable to concentrate on home programs -- either VR goggles, or home projectors.
We would not want someone to "patent" a VR type habituation treatment or software. For this reason, we are writing here explicitly that as of 9/1/2018 as well as from several years prior to this, it is "obvious" to us as well as presumably to any worker in the field that a VR protocol could be implemented that keeps the visual surround "horizontal", as patients roll their heads, or tilt them about other axes. This might be useful both for treatment of MdDS as well as for habituation of vestibular responses in general. It is obvious that this might be achieved using a commercial "VR" goggle as well as perhaps even a cell-phone. "Obvious" things are not patentable in the USA.