Reference
Glossary
The working vocabulary of Mal de Débarquement Syndrome. Inline dotted terms throughout the chapter link here.
- Mal de débarquement syndrome (MdDS) · MdDS · disembarkment syndrome
- A central disorder of persistent oscillatory self-motion (rocking, bobbing, swaying) lasting more than 48 hours, classically after a sea voyage, and characteristically eased — not worsened — by being back in passive motion.
- Maladaptive adaptation
- The core mechanism of MdDS: the brain adapts its vestibular processing to the rhythmic motion of a boat, then fails to readapt to stable ground — leaving a persistent internal sense of rocking.
- Motion relief (the MdDS paradox)
- The near-paradoxical temporary reduction of MdDS symptoms during re-exposure to passive motion, e.g. while driving. A highly characteristic feature that separates MdDS from PPPD and other dizziness.
- Motion-triggered MdDS (MT-MdDS)
- The classic subtype following passive motion (cruise, flight, long drive). It tends to have a better prognosis and to respond better to VOR readaptation than the spontaneous form.
- Oscillatory self-motion · rocking dizziness
- Non-spinning vertigo experienced as continuous rocking, bobbing or swaying — as though still on a boat. The defining symptom of MdDS, distinct from rotational (spinning) vertigo.
- Persistent postural-perceptual dizziness (PPPD) · PPPD
- A chronic functional dizziness worsened by upright posture, motion and complex visual scenes. A key differential — but unlike MdDS it is not relieved by passive motion.
- Repetitive transcranial magnetic stimulation (rTMS) · rTMS
- Non-invasive cortical neuromodulation, applied over the dorsolateral prefrontal cortex, which has shown symptom reduction in MdDS trials — still investigational.
- Spontaneous / non-motion-triggered MdDS
- MdDS arising without a clear motion trigger, sometimes after stress or illness. It is more often associated with anxiety and migraine and tends to be more persistent and refractory.
- Transient mal de débarquement ('sea legs')
- The brief, self-limited after-rocking that most people feel for hours after a voyage. It resolves within 48 hours and is a normal phenomenon — not the syndrome.
- Velocity storage
- A brainstem–cerebellar mechanism that prolongs and integrates vestibular signals. Maladaptive entrainment of velocity storage to rhythmic boat motion is a leading model for how MdDS arises and persists.
- Vestibulo-ocular reflex (VOR) · VOR
- The reflex stabilising gaze during head movement. Readaptation of the VOR to roll-while-viewing-moving-stripes is the basis of the Dai treatment protocol for MdDS.
- VOR readaptation (Dai protocol)
- A treatment in which the patient views full-field moving optokinetic stripes while the head is rolled at the perceived rocking frequency, aiming to re-tune the maladapted vestibular adaptation.