ABSTRACT: Mal de Débarquement Syndrome (MdDS) is an under-recognized but nevertheless common balance disorder, which in most cases occurs after exposure to prolonged passive motion. MdDS, a chronic illness that can last for many years, is manifested by persistent false sensations of rocking/swaying or gravitational pull. MdDS is debilitating as these symptoms and signs are typically accompanied by other presumably secondary physical, cognitive, and affective problems. In addition to motion-triggered (MT) cases, the same or indistinguishable symptoms can occur without a specific trigger, identified as spontaneous-onset (SO) MdDS. Treatment options for MdDS are limited, and it was only recently that a breakthrough was made in our clinical laboratory with physiological readaptation of the vestibulo-ocular reflex (VOR). The premise of this treatment is that MdDS is caused by maladaptation of a functional component of the VOR called velocity storage, which shapes spatial orientation and the perception of self-motion. The treatment has been administered by maneuvering the head of the patient seated inside a cylindrical chamber during a full-field optokinetic stimulation (OKS). Our current success rates immediately after treatment of MT and SO MdDS are 75% and 50%, respectively. A follow-up study indicated that the success rates later fluctuate as well as that a significant number of patients remain sensitive to bright lights, movements of visual objects, and transportation, pointing to the treatment method's limitations. A primary hurdle is access to the treatment. Full-field OKS requires a specialized set-up in a dedicated room, making the treatment possible only in several laboratories around the world. We recently successfully pilot tested the efficacy of virtual reality (VR) goggles for MdDS treatment with the readaptation approach. In this proposed project, VR goggles will be tested on a larger group of patients, and the effects will be compared to those of full-field OKS. If proven to be effective, MdDS can be treated locally to patients in many vestibular therapy offices, not only for initial treatment but also for remedial or follow-up treatment when symptoms return. This proposal also addresses the weaknesses of the VOR readaptation approach by testing complementary approaches. We hypothesize that reducing (habituating) the velocity storage capacity decreases sensitivity to physical movement and improves MdDS symptoms as well as limits symptom recurrence. We further hypothesize that desensitization to visual stimuli can reduce visually induced dizziness frequently observed in patients with MdDS. We will verify whether these complementary treatments will provide a better outcome compared to the readaptation treatment by itself. Lastly, we hypothesize that OKS without head motion can reduce the false sensation of gravitational pull commonly reported by MdDS patients. Two hundred MdDS patients will be recruited for the study. Patients will be tre...