Mal de Debarquement syndrome

Mal de Debarquement, which is French for “sickness of disembarkment”, is a common feature of many sea-travellers who return to land and feel a prolonged sense of illusionary motion or “rocking”. Normally, this “sea-legs”sensation will subside within days. However, for some people the sensation continues for more than 1 month, at which point it has become chronic, and may be titled Mal de Debarquement Syndrome (MdDS).

MdDS was first mentioned in 1881 yet only described clinically in 1987. It is a rare disorder, predominantly in females of ages 40-50 years old, and refers to the false perception of movement, usually as an aftereffect of motion, such as travelling on a boat. MdDS can be classified as motion-triggered or spontaneous, which is non-motion triggered.

One theory around the cause of MdDS is the theory of VOR (vestibulo-ocular reflex) maladaptation. The VOR pertains to the ability to maintain a stable image whilst the head is moving. It is thought that whilst the brain’s VOR is able to adapt to motion, such as the motion of a boat, it is sometime unable to re-adapt back to normal when returning to land. It is thought that this lack of re-adaptation results in MdDS.

Symptoms of MdDS include:

• Gravitational pull
• Visually-induced dizziness
• Anxiety
• Constant sense of self-motion, with fluctuating symptoms
• Migraine
• Photophobia
• Depression

When testing for vestibular dysfunction, it is common that MdDS sufferers will exhibit NORMAL findings on the typical vestibular test battery. Essentially, everything seems normal, but the symptoms are there. One important diagnostic finding in MdDS is that symptoms often feel better during passive motion, for example, when moving in a car. If symptoms are not better during passive motion, it is possible that the person is suffering Persistent Postural Perceptual Dizziness (PPPD).

Science is currently investigating the role of the female hormones in MdDS due its high prevalence in females of ages 40-50 years old, with researchers showing particular interest in estrogen.

There is evidence for optokinetic therapy for MdDS patients, which involves exposure to a visual stimulus in the form of moving lines. The graduated exposure can improve postural stability and the reduce the perception of movement, with the theory being that the visual stimulus during a head-roll promotes re-adaptation of the VOR.