Introduction: Mal de Debarquement Syndrome (MdDS) is the rare condition of enduring rocking sensations and subjective unsteadiness following a lengthy exposure to passive motion. The pathogenesis of MdDS is unknown and the available treatment is limited. Here, we developed an experimental model of MdDS that may facilitate systematic inquiry of MdDS pathophysiology and the development of prevention or treatment strategies for this condition.
Methods: In an initial series of pilot experiments, suitable stimulation devices and conditions were evaluated. The final paradigm consisted of a low-frequency oscillatory motion stimulation, simultaneously deployed as roll and pitch rotation as well as heave on a six-degrees-of-freedom motion platform. Twelve healthy participants were stimulated under this condition for 30 min during free stance. Aftereffects with respect to rocking sensations and posturographic sway were monitored up to 60 min post-stimulation and compared to an initial pre-stimulation assessment as well as to posturographic recordings of spontaneous sway in ten patients with MdDS.
Results: Motion stimulation consistently evoked MdDS-like rocking sensations and postural alterations that lasted up to 45 min after cessation of passive motion exposure. Body sway alterations were most pronounced in anterior-posterior dimension during standing with eyes closed and primarily characterized by a distinct peak in the low-frequency sway spectrum close to stimulation frequency. These postural aftereffects further closely resembled spontaneous oscillatory low-frequency sway observed in patients with MdDS.
Conclusion: Subsequent neurophysiological and imaging examinations are required to investigate whether the model of transient, experimental MdDS actually shares a common substrate with the enduring pathological condition of MdDS.
Keywords: Aftereffect; Body sway; Mal de Debarquement Syndrome; Postural stimulation.