Treatments of Mal de Debarquement Syndrome (MdDS) by Habituation of Velocity Storage

Not Applicable

Completed

Conditions: Mal de Debarquement Syndrome (MdDS)

Interventions: Device: Habituation of velocity storage of the vestibulo-ocular reflex
Device: re-adaptation of the vestibulo-ocular reflex

Registration Number: NCT04213079

Lead Sponsor: Icahn School of Medicine at Mount Sinai

Brief Summary: Mal de Debarquement Syndrome (MdDS) is an under-recognized but nevertheless common balance disorder, which in most cases occurs after exposure to prolonged passive motion. The current treatment approaches focus on reducing symptoms, but they can be retriggered. This project aims to shift the focus of MdDS treatment to permanently eliminating the symptom trigger while also minimizing symptoms.

Detailed Description: Mal de Debarquement Syndrome (MdDS) is an under-recognized but nevertheless common balance disorder, primarily manifested by constant self-motion sensations consisting of rocking/swaying or gravitational pull of the body, which are accompanied by fatigue, migraine, hypersensitivity to light/noise/crowds, visually induced dizziness, and cognitive dysfunctions. As the name implies ("disembarkation sickness"), in most cases MdDS occurs after exposure to prolonged passive motion, specified as motion-triggered (MT) MdDS. However, the symptoms of MdDS can also occur without a motion trigger, termed as spontaneous MdDS. MdDS is debilitating and entails various mental health issues, such as suicidal thoughts, depression, and anxiety. Treatments for this disorder are still limited, as the specific underlying pathophysiology remains unclear. Recently, the team developed the first treatment method that can safely and effectively ease MdDS symptoms in the majority of patients via readaptation of the vestibulo-ocular reflex (VOR). The hypothesis underlying this treatment is that MdDS is caused by maladaptation of the functional component of the VOR called velocity storage, whose readaptation can be stimulated by exposure to whole-field visual motion coupled with head tilts. Over the past several years, more than 500 patients from around the world have been treated with this method. The success rate immediately after this treatment is 75% for MT MdDS, but some patients report return of symptoms after subsequent flights or prolonged car rides. Thus, the effectiveness of the current MdDS treatment protocol can depend on a serious practical limitation of needing to permanently avoid transportation. Building on the previous hypothesis of velocity storage maladaptation, the study team currently hypothesizes that another method, based on the reduction (habituation) of the velocity storage, can also resolve MdDS symptoms. Velocity storage can be greatly habituated within 4-5 days using a protocol previously developed in the study team's laboratory to reduce susceptibility to motion sickness. Preliminary data support the application of this protocol to MdDS. Moreover, since animal-based research suggests that velocity storage habituation is permanently retained, the study team further hypothesizes that this new treatment method yields robust long-term outcomes. In this project, 50 MT MdDS patients with otherwise normal vestibular and neurological functions will be randomly assigned into two groups, one to be treated by velocity storage habituation and the other by readaptation. Patients will be followed up for 6 months. Based on the preliminary data, the study team expects both groups to yield similar initial success rates for symptom improvement. However, the study team expects the group undergoing the habituation protocol to better retain the initial treatment impact in the long term. This project will significantly impact the MdDS treatment practice. The current approach focuses on reducing symptoms, but they can be retriggered by another prolonged exposure to passive motion. The habituation approach on the other hand focuses on permanently minimizing the symptom trigger while also minimizing symptoms. This project will also increase the current understanding of recurrent MdDS.

Recruitment & Eligibility

Status: COMPLETED

Sex: All

Target Recruitment: 47

Inclusion Criteria

Age 18-78.

Exclusion Criteria

Patient with serious spinal, neck and legs injuries will be excluded, since postural ability is essential for both treatments.

Study & Design

Study Type: INTERVENTIONAL

Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
Habituation of velocity storage	Habituation of velocity storage of the vestibulo-ocular reflex	Participants with motion triggered MdDS
Vestibulo-ocular reflex (VOR)	re-adaptation of the vestibulo-ocular reflex	Treatment by re-adaptation of the vestibulo-ocular reflex (VOR) for participants with motion triggered MdDS

Primary Outcome Measures

Name	Time	Method
Subjective Symptoms Self-report of Overall Severity	During treatment (Day 1), Day 5, and 6 month follow up	The overall severity of MdDS-related symptoms was subjectively reported on a single 11-point scale of 0-10, where the score 0 indicated no symptoms and 10 the most difficult of combined symptoms that the patient subject could imagine. Higher score indicates poorer health outcomes. Among the symptoms to consider were: brain fog, head pressure, fullness of ear, heavy head, headache, nausea, blurry vision, fatigue, sensitivity to fluorescent lights, scrolling of computer screen, sensitivity to smell, sensitivity to noise, walking on trampoline, sensation of gravitational pull up or down. Subjects were trained to estimate the level of symptoms to minimize inconsistency.

Secondary Outcome Measures

Name	Time	Method
VOR Indirect Pathway Coupling Gain	Baseline and Day 5	The gain of the indirect VOR pathway is the term that determines the contribution of velocity storage to the profile of eye rotation speed during prolonged whole-body rotation. The measure is normalized to the head rotation velocity and is thus unitless.
VOR Indirect Pathway Time Constant	Baseline and Day 5	The velocity storage mechanism is an indirect component of the VOR that facilitates the reflex by storing and releasing signals related to head rotation, for example by prolonging the eye movement response beyond the peripheral vestibular activity during head movement and generating similar eye movement response to rotational cues provided by other sensory modalities. The time constant of this indirect VOR pathway is the rate of charging/discharging in the exponential ideation of its behavior, measured in seconds, estimated from the profile of eye rotation speed during prolonged whole-body rotation that is the combination of the contributions from the direct and indirect pathways.
Visual Vertigo Analogue Scale (VVAS)	Baseline and 6 month follow up	Visual Vertigo Analogue Scale. There are 9 separate visual analogue scales to rate intensity of visual vertigo provoking situation. Each scale is on a 0-10 cm line. Full scale from 0-10. Higher score represents more dizziness.
Dizziness Handicap Inventory (DHI) Questionnaire	Baseline and 6 month follow up	Physical, emotional, and functional disability related to MdDS will be assessed with DHI. DHI is a 25-item self report questionnaire, total score range from 0 to 100, with higher score indicating more perceived disability.
VOR Direct Pathway Gain	Baseline and Day 5	The vestibulo-ocular reflex (VOR) is a class of reflex eye movement that counters head movement to stabilize vision. A perfect stabilization occurs when the velocity of the retinal image slip is zero, i.e. when the ratio, or gain, of the eye rotation speed to the head rotation speed is one. The VOR is a fast reflex whose direct pathway consists of a three-neuron arc, but also has parallel, indirect pathways that allow integration of signals from the peripheral vestibular organs with those of other sensory modalities such as vision and proprioception to modulate the eye movement response. The gain of the direct VOR pathway is the ratio of the eye rotation speed to the head rotation speed at the onset of head rotation, and is a unitless measure.