Timothy C. Hain, MD Page last modified: January 19, 2013
Mal de Debarquement or "MDD" is a type of vertigo and imbalance that occurs after getting off of a boat. The usual situation is that of a middle aged woman who has gone on a cruise. We use the abbreviation "MDD" here for clarity, because it has been used in the past. It has been pointed out that "MDD" can be confused with other disorders, and some prefer to use "MdDs" or various combinations of these letters.
To our knowledge, the first reference to the syndrome was made by Erasmus Darwin, in 1796. He wrote:
"Those, who have been upon the water in a boat or ship so long, that they have acquired the necessary habits of motion upon that unstable element, at their return on land frequently think in their reveries, or between sleeping and waking, that they observe the room, they sit in, or some of its furniture, to librate like the motion of the vessel. This I have experienced myself, and have been told, that after long voyages, it is some time before these ideas entirely vanish. The same is observable in a less degree after having travelled some days in a stage coach, and particularly when we lie down in bed, and compose ourselves to sleep; in this case it is observable, that the rattling noise of the coach, as well as the undulatory motion, haunts us. " (Darwin, 1796).
Table1: Characteristics of MDDS
Median Duration (mo)
Cha et al, 2008
Hain et al, 1999
3.5 (6 mo to 10 years)
Brown and Baloh, 1987
Total or (average)
Table 1 summarizes the available literature about MDDS. It is a disorder that mainly affects women (87%) in their mid 40's. Except in California where men are also affected, (the site of Dr. Cha's study), most individuals with MDDS are women who go on a 7-day cruise. After getting off the boat, or "debarking" (debarquement), they develop a rocking sensation, as if they are still on the boat. The rocking sensation may persist for months or even years ! Most people seem to have it for a month or less though -- our study largely recruited people with longer duration symptoms, 3.5 years was the mean (Hain et al, 1999)
Table 2: Features Distinguishing MDDS from Land-sickness (LDS)
1 or more months
2 days maximum
About 90% female
Motion-sick on boat
Relieved by driving
There are several variants of motion induced malaise, that are not MDDS. Table 2 lists the features that distinguish MDDS from simple land-sickness. Land-sickness (LDS) is common, and between 41% and 73% of persons disembarking from seagoing voyages experience a brief unsteadiness syndrome (Gordon, Spitzer et al. 1995; Cohen 1996; Gordon, Shupak et al. 2000). Common LDS typically persists for 2 days or less. Persons with LDS are also likely to have sea-sickness, (Gordon, Spitzer et al. 1995) while persons with MDDS generally are untroubled by sea-sickness. Males and females do not appear differ significantly in the incidence, intensity, or duration of land-sickness symptoms. (Cohen 1996). LDS, confusingly, is also termed "mal de debarquement" by some. Table 1 does not include reports or data concerning subjects who symptoms that last less than 1 month, i.e. potential land-sickness, except for the work of Cha, in whom the duration of patients with "classic" MDD could not be determined due to study design(Cha, Brodsky et al. 2008).
MDDS also has some similarities to motion sickness (sea sickness, mal de mer). However, MDDS is again easily distinguished by the relatively short duration of motion sickness and gender distribution. Persons with MDDS reliably have relief of symptoms when in motion, such as driving a car, but experience recurrence of rocking once motion has stopped (Hain, Hanna et al. 1999; Cha, Brodsky et al. 2008). In motion sickness, many persons find driving very difficult. This is also often true for persons with vestibular disorders.
MDDS also overlaps with a little studied group of patients called "rockers", who develop similar symptoms to MDDS, without a preceding motion exposure. (Cha 2012) Often these patients develop head or trunk rocking, which is called "titubation" (Wassmer, Davies et al. 2003). In our clinical experience, the age, gender and pattern of medication responsiveness of this group are similar to those of MDDS. Although titubation is associated with cerebellar disturbance, evidence of cerebellar damage is generally not found in "rockers".
Little is known about this rare disorder. It is the general opinion, however, that MDDS is not caused by an injury to the ear or brain. At this writing (2012), the predominant opinion is that MDD is a variant motion sickness. While this theory doesn't explain why MDD seems to mainly affect women in their 40's it does seem to account for observations of naval personnel who have a similar land-sickness experience.
Some dizziness experts believe that MDDS is caused by a variant of migraine. Others think that it is caused by inappropriately high weighting of somatosensory input for balance (Naichem et al, 2004). As somatosensory information and vestibular are unreliable on a boat, this is a difficult explanation to follow. We think that the internal model theory explanation (which follows) is the better one at this writing (2007). A recent conjecture is that MDDS is caused by adaptation to roll while rotating. In other words, if one is rocking side-side (roll), and also rotating the head, for long periods of time, one might develop an inappropriate cross-coupling between roll and rotation (Dai et al, 2009). Our position on this idea is that it could explain brief (2 hour) symptoms after getting off of a boat, and also offers an explicit hypothesis that might be tested formally (i.e. people who do a lot of head rotation on a boat would be more likely to get this than people who sit quietly).
Because the condition largely occurs in females, it may also have something to do with sex hormones, such as estrogen or progesterone. It could also be genetic, related to two copies of the 'X' chromosome perhaps combined with other susceptibility factors. The "Norwalk" virus is common on cruise ships, and perhaps this syndrome is somehow related to this virus.
It seems unlikely to be a psychological disturbance -- although it is always difficult to entirely exclude psychological problems, the male:female ratio and other aspects of this disorder would make this unlikely.
Moeller and Lempert (2007) recently suggested that MDD is due to "deafferentation" or panic. We disagree with both of these ideas.
Cha et al (2012) recently reported changes in brain connectivity in persons with MDD. MDD seems to be associated with changes metabolism in the brain, in circuits related to vision, vestibular processing and emotional reactions. It would be interesting to see how much of this is due to MDD and how much is secondary to being dizzy.
There are some reports of MDD following use or withdrawall from serotonergic medications. The connection here is that serotonin may inhibit glutamate, an excitatory transmitter in the vestibular nucleus (Smith and Darlington, 2010.). This idea also provides an explanation why serotonergic medications may help MDD (see treatment section).
Note that the MDD of "Mal de Debarquement" has nothing to do with the other MDD of "Manic Depressive Disorder". The support group for MDDS, being sensitive to this, has suggested that the proper name of the syndrome would best be "MdDs". Our own feeling is that there are many medical disorders that share initials with other disorders (PAN is an example -- periodic alcohol nystagmus and periodic alternating nystagmus), and one should not get too anxious about the initials
A plausible mechanism for the development of MDDS is that it is due to formation of an inappropriate internal predictive model. Internal models are sophisticated estimators that have been used to explain such difficult observations that one cannot "tickle" onself (see the work of Wolpert and others). Examples of internal models are very easy to find in daily life -- suppose you pick up a suitcase, expecting it to be full, but it is empty ! Internal models are sophisticated methods of reacting to events even before they happen !
On a boat, one is faced with a difficult balancing problem, with components of rotation (pitch plane rotation -- about the axis between the ears), and linear movement (surge -- front-back movement of the boat). Both are somewhat predictable as the boat is large and it's interface between it and the ocean constrains it to low frequencies of movement.
Lets take an example -- when the boat pitches (rotates) forward, there is a small amount of pushing the person backward accompanied by a tilt of the visual world as the angle between upright and the boat surface becomes more acute. To stay upright in response to pitch, a person should not activate their ankle muscles much as inertia tends to keep their body upright. Vision is accurate on the deck but inaccurate inside. Thus vision is unreliable. Although there is rotation around the ankle joint, and thus somatosensory input, there should be no "righting" response from the person because the body is upright in space. Visual responses are correct on deck and incorrect inside, and thus a "rule" cannot be made. The rule then for pitch rotation of the boat, one should ignore somatosensory information signaling rotation . Thus for pitch of the boat, a selective "downweighting" of somatosensory information, or both somatosensory and visual information according to context, would be a reasonable adaptation (or rule).
For linear acceleration of the boat under the person, or "surge" as it is called in nautical contexts, inertia attempts to keep the person still in space, but due to shear force at the feet, the person becomes destabilized and rotates at the ankles. Then vision, vestibular and somatosensation senses are activated by the bodily rotation with respect to the boat, and an active response is needed to prevent a fall. Thus for surge of the boat, no relative sensory reweighting would be needed, although increased responses to all types of input might be helpful.
How does the brain figure which rule to apply ? We propose that people develop a predictive model of the boat motion, and use their prediction to select the rule to apply for boat motion (and avoid falling).
Normally, it seems likely that over a few days, people develop an internal model of periodic motion on the boat so that they predict and cancel out input (visual or somatosensory) that is phase-locked to pitch rotation, and enhance responses due to surge that is not. The internal model normally is disposed of once the person returns to terra firma, again over a period of hours to days. Persons with MDD are unable to dispose of this internal model, which is only useful when they are exposed to periodic motion (such as when driving a car).
This theory explains most of the features of MDD.
What does the data say ?
With respect to the hypothesis that MDDS is caused by reweighting of visual, vestibular or somatosensory input, the data so far is contradictory. Nachum and associates used posturography to study young males aged 18-22 with motion sickness and land-sickness (they considered land-sickness to be equivalent to mal de debarquement in their paper -- see table 2 above). They reported that these young men developed increased reliance on somatosensory input after motion exposure, and reduced weighting of vision and vestibular input (Nachum, Shupak et al. 2004). While the accuracy of visual input depends on whether one is inside the boat or on the deck, semicircular canal input is accurate on boats, and somatosensory input is intermittently accurate. Accordingly, it is difficult to understand a rationale for this adaptation. An intrinsic problem with this study is that the study group were persons with young men motion sickness and land-sickness, not middle aged women with the month or greater MDDS syndrome.
A more reasonable possibility is that individuals with MDDS may develop an increased reliance on visual and vestibular information (and thus decreased somatosensory weighting). This occurs in normal subjects who are exposed to situations where somatosensory feedback is distorted (Peterka, 2002), and would also be a reasonable adaptation to boat pitch. Either adaptation might result in inaccurate land sensorimotor integration. Nevertheless, neither of these adaptations explain the rocking sensation of MDD or the characteristic improvement on driving a car.
The diagnosis of MDDS is made by a combination of the history (rocking after prolonged exposure to a boat or other source of prolonged motion), improvement with driving, and exclusion of reasonable alternatives. A motion exposure of 2 hours is a bare minimum. The typical duration of exposure is a week.
Tests to exclude Menieres disease should be done, and if there is a history of plane flight, perilymph fistula should also be considered. A typical patient is a woman of appropriate age (see figure above), who has gone on a cruise and who is now rocking. Recently, the criterian has been expanded to require getting better on driving. This feature is extremely common in MDD, but extremely rare in inner ear disorders or Migraine.
In my practice, I get the following tests, in persons who are not "classic" -- i.e. not improved by driving and not on a cruise, see table 1:
If people are "classic", I get no tests at all.
After MDDS has started, most medications that work for other forms of dizziness or motion sickness are ineffective. Specifically, antivert (bonine, meclizine), dramamine, and scopolamine seem to be of little use. The author has tried out many other medications, and has also not found response to more unusual agents for dizziness such as betahistine, baclofen, or verapamil. The usual treatment strategy for MDDS is to attempt to make the patient comfortable, while waiting for the MDDS to end by itself (typically within 6 months, see table 1). Conventional vestibular suppressants that affect anticholinergic pathways such as meclizine and transdermal scopolamine are not helpful in MDDS. (Hain, Hanna et al. 1999) Benzodiazepines, such as clonazepam, are of the most benefit. (Hain, Hanna et al. 1999; Cha 2012), and SSRI type antidepressants are also suggested as being potentially helpful (Cha 2012). There are also anecdotal reports of good responses to gabapentin, amitriptyline, and venlafaxine – all medications that are also helpful in migraine.
Medications to stop and procedures to consider stopping.
Medications taken prior and during boat travel might prevent development of MDD.
Physical therapy: The evidence for a positive role for Physical Therapy in MDD is somewhere between nonexistent and weak (Hain and Helminski, 2007). In our original study, 10/15 persons who had vestibular rehabilitation reported improvement, but the natural history of MDD is to improve, and one wonders what would have happened had they not undergone rehabilitation. In other words, this was an uncontrolled study, which sheds no light on whether PT is helpful. Cha commented in passing that "only rare patients seem to be cured by vestibular therapy". (Cha 2012). In fact, the only literature describing physical therapy treatment for MDDS is a single case report. (Zimbelman and Watson 1992). Of course, it is not known how this case would have done without PT. In general, while many individuals with MDDS undergo vestibular rehabilitation, again because of a lack of controls, it is not possible to determine whether they did any better than persons who were not treated (Hain, Hanna et al. 1999). Thus the efficacy of vestibular rehabilitation for MDDS is unknown.
Motion sickness has been treated successfully with habituation (Dai, Raphan et al. 2011), and one might reasonably argue that MDDS, being a motion sickness variant, might also respond to a similar approach. Habituation entails a down-weighting of motion input, and can reduce the long duration vestibular responses commonly associated with motion sickness susceptibility (Dai, Raphan et al. 2007). Although there are well developed self-directed motion habituation protocols such as the PUMA exercises (Puma 2010), there are presently no published reports of their efficacy in MDDS (or motion sickness for that matter). Nevertheless, we are sympathetic to the general idea that things that make you feel worse (when you are dizzy) usually does result in some improvement (if you can stand it). The Puma protocol exercises are just so extremely stimulating that so far -- nobody has been able to tolerate them for more than a session or two. The Puma protocol exercises can be bought on the web in the form of a DVD from Dr. Puma's website.
While we find this idea very doubtful, if MDD is indeed due to inappropriately high weighting of somatosensory input, vestibular physical therapy protocols that teach down-regulation of somatosensory input may be helpful. A controlled trial of vestibular rehabilitation in MDD would be helpful.
If MDDS is instead caused by an internal oscillator developed to predict boat motion, one's treatment strategy should be aimed at manipulation of psychological variables rather than somatosensory integration. Patients need to ignore their aberrant internal signal, in the same way that most persons with tinnitus eventually develop an ability to ignore abnormal internally generated sounds. Treatments that decrease vigilance, obsessiveness, and anxiety as well as "tincture of time", would be the optimum strategy. If this conjecture is correct, therapy that focuses attention on the rocking sensation could even be counterproductive.
Going on another boat:
MDD is not very well studied. As of 2013, only 29 papers come up on a "Pubmed" search for "mal de debarquement". Considering that many other obscure conditions have 1000's of papers written about them, this means that MDD has been generally ignored. There are many open questions. Here are a few:
We know of three ongoing research projects regarding MDD, one in Oklahoma (Dr. Cha), another in Ohio(Clark), and a third in New York (Dai). An abstract concerning the research project in Ohio is here.
There is a MdDs foundation, which maintains it's own website and encompasses quite active group of volunteers. The author of this page, Dr. Hain, is loosely associated -- I sometimes provide some advice to this group.
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