Abstract
In many patients with an acute unilateral vestibular deafferentiation (uVD) syndrome symptoms are expected to resolve spontaneously because of central compensation. However, more detailed observations have revealed that 29-66 % of uVD patients develop disabling chronic dizziness lasting >1 year after the acute event. Identifying predictors of chronic dizziness would allow patients at high risk to be targeted with personalized therapies to reduce healthcare costs. Therefore, the main objective of this study is to identify predictors of chronic dizziness after an acute uVD.
Despite the consensus on the usefulness of physical therapy, incorporation of physical therapy programs in daily management of patients after acute uVD remains troublesome. The approach usually consists of encouraging patients to move around as much as possible without the supervision of the physical therapist. However, there are no known studies that investigate exercise adherence in acute patients who rehabilitate based on home exercise programs. Therefore, the first objective is to study the effect of the actual level of physical activity in the acute stage on long term (LT) outcome.
Recent data show that LT prognosis is more linked to anxiety and somatization traits than to objective vestibular findings. Avoiding complaint-inducing movements is a known compensation strategy used by patients with an acute uVD. However these movements are very important to promote compensation. Therefore, the second objective is to study the effect of activities avoidance behavior on LT outcome.
As stated above it is questioned whether objective vestibular findings can predict chronicity. However recently the Perez and Rey (PR) score was developed. It is a measure of temporal organization of refixation saccades that enables to distinguish between compensated and uncompensated vestibular patients. Therefore, the third objective is to study the effect of early central vestibular compensation as measured by the PR score on LT outcome.
In patients with poor central vestibular compensation the remaining sensory cues will need to compensate for the loss of vestibular information. Patients using a visual compensation strategy can become dependent of stable visual cues. Evidence is mounting that visual field dependency is a factor contributing to visual vertigo which is a specific form of persistent perceptual postural dizziness (PPPD) which is classified as a chronic functional vestibular disorder. Therefore, the fourth objective is to study the effect of visual motion sensitivity on LT outcome.
A 2-year prospective cohort study will be performed to study aforementioned risk factors for chronic dizziness. Up to 200 consecutive patients with an acute uVD will be included. Triage at the emergency department is performed by neurologists and ENT clinicians. All patients will undergo a standard ENT evaluation for dizziness. Subsequently they will be treated by means of symptomatic treatment (antivertiginous drugs) and early start of vestibular rehabilitation. Patients will be seen by a physical therapist at all measurement sessions within the first three months. Chronic dizziness is indicated by a score >30 on the Dizziness Handicap Inventory (primary outcome) after 6 months. In addition, the criteria from the Barany society will be used to see whether patients suffer from PPPD (visual vertigo) or not. Possible risk factors will be evaluated by using MOX1-activity loggers (objective 1), the Vestibular Activities Avoidance Inventory (objective 2), video Head Impulse Testing including the Perez & Rey score (objective 3), Subjective Visual Vertical test and Rod & Disc test (objective 4). Measurements will be taken 1, 2, 3, 6, 9, 10, 26 and 52 weeks after the acute event. The risk factors will be used as predictors in a logistic regression model, that predicts whether a patient will have a DHI-score above or below 30. The predictive accuracy of the model will be assessed using ROC curves.
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