Mal de debarquement literally means "sickness of disembarkment." This term originally referred to the illusion of movement felt as an aftereffect of travel by ship or boat. Some experts now include other types of travel, such as by train and airplane, and situations with new and different movement patterns, such as reclining on a waterbed.

Exposure to unfamiliar movement and then the cessation of that movement initiates mal de debarquement. Sea travel is the most common starting point for the disorder. For a handful of people, this illusion of movement seems to last for long periods of time: weeks to months, even years after a voyage. Some physicians refer to it as mal de debarquement syndrome (MMDS), reflecting that it is a collection of symptoms rather than a specific disease. There is no universal agreement among physicians about what mal de debarquement is or how to diagnose it. Not all doctors even agree that persistent mal de debarquement exists.

Leading explanations for the syndrome conclude that the problem is not in the inner ear and most likely occurs someplace in the balance areas of the brain. The brain adapts to the motion of the ship or other vehicle; but once the movement stops, the brain is unable to readapt once again. Why this ability to adapt would suddenly stop is not understood. One theory is that certain movements, such as experienced in a boat, expose a person to simultaneous upward and downward movements, along with tilts to the left and right, as well as forward movement in a nearly straight path. During this time the brain must send out signals to the leg and body muscles so that they move in ways that will counter the different, rhythmical shipboard movements. Adaptation to such movement is sometimes referred to as gaining “sea legs.” These new patterns of adjustment are unlike usual movements, so it may be that the brain becomes accustomed to this new pattern of signals and cannot return immediately to the old patterns once the movement stops. This prevents the redevelopment of “land legs.”

Another theory is that mal de debarquement is a migraine variant; long-lasting mal de debarquement is experienced by middle-aged woman more than by other groups, and more women than men experience migraines.

Symptoms of mal de debarquement include the sensations of bobbing, rocking, swaying, swinging, floating or tumbling. These may be accompanied by unsteadiness, disequilibrium, anxiety, difficulty concentrating, and a loss of self-confidence. The symptoms usually increase in enclosed spaces and when trying to be motionless, as when attempting to fall asleep in bed or when stopped at a traffic light. They improve during constant, steady movement such as experienced while in a moving car. Mal de debarquement does not include other symptoms associated with vestibular disorders, including spinning vertigo, vomiting, cold sweat, ear pressure, ear pain, sound sensitivity, tinnitus, hearing loss or distortion, double vision, or bouncing vision.

Persistent mal de debarquement usually begins within hours of stopping the novel movement and resolves within about six to twelve months. There are also reports of it not resolving for years.

A physician diagnoses mal de debarquement by collecting a thorough history, conducting a physical examination, and doing tests to rule out other causes for the symptoms. For a diagnosis of mal de debarquement to be made, there must be a history of a ship voyage or other new movement, the return to a normal environment, and then the start of the symptoms. Symptoms start immediately, not weeks or months later.

At this time there appears to be no single highly successful treatment approach to mal de debarquement. Standard drugs given for motion sickness (including meclizine, diphenhydrinate, and scopolamine patches) seem to be ineffective. Some treatments suggested by physicians include walking while watching the horizon, vestibular rehabilitation therapy, diuretics, anti-seizure drugs, antidepressants of the tricyclic family, and benzodiazepines. However, when benzodiazepines or antidepressants are stopped, the symptoms can reappear, at least for a while, and seem stronger than they were before the treatment began. This phenomenon is generally referred to as “rebound.” 

Although there is no single established method of symptom management, some useful coping tips include:

• Reducing stress and getting a full night's sleep is vital.
• Vestibular rehabilitation therapy (VRT) and home-based exercise has been helpful to some people with MMDS.
• When driving, move your head while stopped at a traffic light, and still and look ahead for a few minutes prior to leaving the car.
• After the end of an activity with constant movement, take a walk while focusing on the horizon.
• If your symptoms are lessened by movement, try using a rocking chair during sedentary activities.