A little-known disorder of balance, causing an illusion of continuing movement, lasting weeks or months, even years, after a period of exposure to an episode of persistent movement.
MDD, debarkment or disembarkment syndrome.
What is this?
An abnormal sensation of continuing movement and discomfort after fairly prolonged exposure to motion, almost like experiencing some aspects of sea-sickness continuing long after you have landed. Originally described after travelling at sea, it has since been described after train travel and flights, or even after spending time on a water-bed! It has also been described in astronauts after returning to earth after a journey into space. It seems to occur more often in women.
What causes this?
It appears to be due to a problem of a type not fully understood, in the areas of brain dealing with balance, rather than with the organs of balance within the inner ear. Having adjusted to a period of continuing motion, the brain seems to fail to recognise that the motion has ceased. Some consider it a variant of migraine. So it's a failure of re-adaptation to conditions of rest.
What are its symptoms?
A sensation of rocking, swinging, or similar motion while at rest, along with unsteadiness and disequilibrium, and anxiety. It may feel worse while sitting or lying at rest in bed, and better during a condition of steady movement, such as walking or being driven as passenger in a car. It does not include vertigo, nausea, vomiting, sweating or visual disturbance. The symptoms tend to start within hours of the stopping of the novel movement that appears to have set this off, and tend to last for 6 to 12 months. Rarely, it may apparently last for years.
How is it diagnosed?
The disorder is still controversial, and there isn't full agreement even as to whether this is a valid diagnosis, let alone how to diagnose or manage it. Diagnosis is made mainly by excluding other possible causes of the symptoms, combined with a typical history. The usual tests of balance and neurological examinations are usually normal.
How is it treated?
No single treatment method has been broadly accepted as useful. The drugs used for motion sickness (diphenhydrinate, meclizine, or scopolamine patches) seem not to help. Among the treatments used are walking while watching the horizon to orient oneself, tricyclic antidepressants, anti-epileptic medicines, even diuretics. Some find relief from benzodiazepine tranquillizers, but there is concern that long-term use may lead to dependency. Physical activity does seem to be helpful.
What is the prognosis?
Generally the unpleasant symptoms fade away within months, but they may persist for years.
When to call your doctor.
If you experience typical symptoms after a significant period of travel or other cause of persistent irregular movements.
How can it be prevented?
There's no known way of recognising the risk or preventing the first episode. But it does seem common, once the symptoms have disappeared, for the syndrome to recur after another long flight or cruise. Some believe that using a benzodiazepine during such a subsequent journey may reduce the risk of recurrence.