Disembarkment syndrome or Mal de Debraquement Syndrome (MdDS) is the sickness of disembarkment originally coined for the illusion of movement experienced by an individual after sea travel, but recently researchers have also used it to include other modes of travel. Though it has been around for a while, MdDS has not been recognised internationally and awareness about the disease is poor. A lack of interest in this disease has also resulted in poor research and definitive treatment.
The condition has been under reported in medical literature with the disease considered to be in existence for centuries because of sea-faring people. A popular reference made by MdDS awareness volunteers is about Charles Darwin’s father writing about him experiencing symptoms similar to MdDS after boat and stage coach travel in the 1700s. In the year 1999, a series of 27 MdDS cases were reported which had a male to female ratio of 1:9. The male-female ratio has been reaffirmed in recent surveys by the Mal de Debraquement Syndrome Foundation. In 2010 a survey conducted by the MdDS Foundation revealed 243 female patients and 19 male patients diagnosed with MdDS and the average age was between 43 – 45 years.
There are two main types of MdDS experienced by patients, the first and more popular being triggered by motion and the other has no apparent cause or known trigger, named as spontaneous MdDS.
MdDS is experienced as a withdrawal syndrome, when a patient experiences unfamiliar motion while travelling through any mode of transport and then becomes detached from that movement. Most number of cases have been reported after sea travel by patients. There is no solid explanation about why only a fraction of the travelling community develops this syndrome and the higher number of cases occur with the female population.
A popular theory brought forth as an explanation for the onset of the syndrome states that the problem is not related to the inner ear as proposed earlier but of the brain. The syndrome takes place someplace in the balance area of the brain which gets accustomed to the sea movements and is not able adjust to the land stillness once the travel ends. There is no proper explanation why this ability to readapt stops functioning and also why it affects only a certain number of people.
Dr Yoon-Hee Cha, one of the very few researchers working to understand this syndrome presented a paper on MdDS in an American Academy of Neurology meeting. The paper findings are based on PET and fMRI studies conducted on 20 patients with motion triggered MdDS and 12 patients suffering from spontaneous MdDS. The studies pinpointed that the fundamental problem in MdDS is that there is greater connectivity between the areas that process and store spatial information (information of location of objects), while there is less connectivity between these areas and the areas that regulate the storage areas. This lack of connectivity may be the cause of the illusion of motion.
The symptoms displayed by MdDS most commonly include a constant sense of motion characterised by bobbing, rocking swaying side to side (sea legs), difficulty in concentration, loss of self confidence, swinging, tumbling, loss of balance and more. The symptoms do not have a fixed trigger and could be observed anytime during the day, only with varying intensity. Although none have yet been able to explain the cause of varying intensity, there are reports which suggest increased symptoms during the evening period. The most commonly known triggers are fatigue, bright lights, dark rooms, running on a treadmill, illness as well as shopping, household chores and walking in crowds. The MdDS symptoms might persist for a month, a couple of months or it may never get resolved at all, which differs from the general symptoms of “Land Sickness” observed by most travellers after long journeys.
Because of the lack of research and awareness about this disease, it goes undiagnosed or misdiagnosed most number of times. There are no definitive tests to determine but doctors might recommend some neural and vestibular tests. Diagnostic procedures are based on ruling out other diseases with similar symptoms like BPPV or labyrinthitis. The tests recommended by a physician include posturography and rotary chair test for assessing the balancing function of the body, MRI scan for neurological assessment and caloric tests for checking the vestibular system. The diagnosis heavily depends on patient history which might be indicative of MdDS like a recent travel.
Since there is no definitive diagnostic procedure for MdDS, the physicians rely on ruling out medical conditions with similar symptoms to arrive on a conclusion.
Benign Paroxysmal Positional Vertigo (BPPV)
The BPPV symptoms are caused by a sudden jerk movements of the head like instantly lying down on the bed, suddenly getting up from your chair or quickly jerking your head in a certain direction. The onset of BPPV leads to a vertigo attack and nystagmus (eye movement). Though severe, the attack might usually last only for a minute or two as compared to the constant symptoms displayed by MdDS. The trigger for BPPV is the head movement which has nothing to do with triggering MdDS as explained in the symptoms section.
The attacks of unsteadiness caused by Meniere’s disease are quite similar to that of MdDS and are more severe than the attacks related to BPPV. Unlike MdDS, this can be treated or controlled with drugs and diet.
There is no definitive cure for MdDS but there are treatments available to curb the underlying symptoms. Anti-vertigo medication such as Valium might be helpful to a small extent in bringing down dizziness, inner ear disorder or motion sickness. These medications are habit forming and hence prolonged intake is not recommended. The balancing problems are addressed with vestibular rehabilitation / therapy to control the loss of balance. Other treatment options suggested might include diuretics, anti-seizure drugs and antidepressants of the tricyclic family. Since there is no definitive treatment, physicians heavily rely on their previous experiences of handling such cases.
The MdDS Balance Disorder Foundation is an online support group which is most active of the various support groups on the internet. This online community is a knowledge base for MdDS and related information as well as a support group for patients. They conduct independent surveys for and hold events for generating awareness about the medical condition.