The goal of this exploratory study is to gain a better understanding of the symptomatology of idiopathic bilateral vestibulopathy (IBV) by characterising as precisely as possible the type and intensity of each patient's peripheral vestibular deficit, and to investigate the link between this symptomatology and some functions influenced by the vestibular system (i.e. cognitive, emotional, vegetative functions).
Bilateral vestibulopathy (BV) is defined as total or partial impairment of vestibular function on both sides, leading to chronic postural and visual instability. Idiopathic bilateral vestibulopathy (IBV) is a rare condition characterised by acquired BV of unknown aetiology. Although described more than thirty years ago, IBV remains a condition with imperfectly understood contours, mechanisms and consequences. The peripheral vestibular system, located in the inner ear, is the main balance organ. Sensory information from the vestibular system is distributed to different brain structures, which perform a wide range of functions, such as maintaining stability of gaze and posture, controlling certain functions such as sleep, spatial memory and emotional processes, and perceiving movement, spatial orientation and self-image. The most common symptoms of IBV are persistent postural instability, and, when moving the head and body, a reduction in visual acuity that can go as far as a sensation of instability of the visual environment. Patients also often report problems with orientation and spatial memory, poor body shape, sleep disorders, attentional problems, and anxiety or depression. Because little is known about this disease, diagnosis often comes late, after several years of various explorations and consultations with doctors and specialists. Based on the observation that patients suffering from IBV have heterogeneous peripheral impairments, both qualitatively (type of sensory organ affected) and quantitatively (the impairment is more or less complete), and that the sometimes complex symptomatology is difficult to relate to the type of peripheral deficit, the aim of this project is to gain a better understanding of the symptomatology of IBV by evaluating certain functions that have recently been shown to be influenced by the vestibular system, and to relate this to the type and intensity of the peripheral deficit. Hence, the main aim of this project is to study the link between symptomatology - both 'classic' (posturo-oculomotor) and cognitive, emotional and vegetative - and the type and intensity of vestibular disorder.
Study Type
OBSERVATIONAL
Enrollment
69
This assessment, designed to evaluate the impact of the vestibular deficit on everyday tasks, will include questionnaires and standardised clinical tests. The questionnaires are the Fall Efficacy Scale; the Dizziness Handicap Inventory; the Oscillopsia Severity Questionnaire; the Hospital Anxiety and Depression Scale; the Hamilton Anxiety Scale; the Global Physical Activity Questionnaire; the Motion Sickness Susceptibility Questionnaire part B; and the Cambridge Depersonalization Scale. In addition, three standardised clinical tests will be carried out: Five Times Sit to Stand Test; Tandem walking test; and Fukuda step test (50 steps). Five specific clinical tests will also be carried out: Sit-to-stand-with-walk-and-turn; Perception of active body rotation; Perception of walking distance; Triangle Completion Task; and Gait assessment.
Four cognitive tests from the French Focus Group on Executive Functions Assessment (GREFEX) battery will be carried out: the Stroop test; the Trail Making Test; the Baddeley's dual task; and a test of Corsi's Blocks.
UMRs 1075 COMETE Unicaen INSERM
Caen, Calvados, France
Center of pressure (CoP) path length
Stabilometric data: Total length travelled by the CoP (in mm)
Time frame: Posturography is assessed once, during about 30 minutes.
Center of pressure (CoP) path amplitude
Stabilometric data: Maximal distance over two points of the stabilogram (in mm)
Time frame: Posturography is assessed once, during about 30 minutes.
Center of pressure (CoP) surface area
Stabilometric data: surface travelled by the CoP (in mm²)
Time frame: Posturography is assessed once, during about 30 minutes.
Ocular torsion
During eccentric axis rotation: measure of the torsion of the eyes (in degree)
Time frame: Unilateral utricular otolith function is assessed once, during about 30 minutes
Duration estimate
During the time perception task, subjects are asked to estimate several durations (in seconds).
Time frame: Time perception task is completed once, during about 30 minutes.
Duration production
During the time perception task, subjects are asked to produce several durations (in seconds).
Time frame: Time perception task is completed once, during about 30 minutes.
Number of correct tandem steps
During tandem stance and walk, subjects are asked to stand upright in a heel-to-toe fashion with their arms crossed on their chest and walk.
Time frame: Assessment of postural stability and active motion perception is completed once, during about 30 minutes
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This test, also known as the unilateral centrifugation test, provides a quantitative assessment of unilateral utricular otolith function, whereas the tests currently used (vestibular evoked myogenic potential, VEMP) only provide a qualitative assessment.
To assess the participants' bone mineral density, the reference technique of densitometry using two-photon absorptiometry will be used.
Participants' ability to maintain their balance will be assessed using measurements taken on the Synapsys platform. To standardise their position, they will have to stand on the platform with their feet apart, arms at their sides and look straight ahead. Volunteers will be asked to sit down between each trial. The surface area and length of the centre of pressure will be measured under open-eye balance conditions with and without image reading/exploration and dynamics. During this test, 9 balance assessment situations lasting approximately 1 minute each will be performed.
Participants will be seated on a rotating chair in the dark. Using a virtual reality headset, three visual stimuli will be presented: (A) no visual stimulus (darkness), (B) visual stimulus corresponding to a displacement of the participant along a cylindrical trajectory, (C) visual stimulus corresponding to a displacement of the participant along a conical trajectory. These 3 types of visual stimuli will be presented alone or during an Off-Vertical Axis Rotation (OVAR) with the chair axis inclined at an angle of 10° to the vertical and a rotation speed of 60°/s. During each sequence, blood pressure, heart rate and end-tidal carbon dioxide (CO2) will be continuously recorded using standard medical equipment.
Participants will have to complete five standardised clinical questionnaires: Pittsburgh Sleep Quality Index; Spiegel questionnaire assessing sleep quality; Morningness-Eveningness questionnaire; Insomnia Severity Scale; and Epworth Sleepiness Scale. Moreover, the activity/rest rhythm will be measured continuously by actimetry over a period of 11 days. The volunteer will also have to wear a Somno-Art® bracelet all night long during the eleven days of monitoring to collect the volunteer's actimetry and heart rate in order to specify which sleep stage the volunteer is in and thus monitor changes in sleep stages over the course of the night. Finally, participants will have to complete a sleep diary.
* Classic geometric illusions (inverted T, Mueller-Lyer, Ponzo, Poggendorff, Zoellner, Hering) which generate systematic distortions will be used. * Time perception task: Participants will wear a virtual reality headset in which instructions will appear for 6 consecutive tasks each repeated 10 times with different durations. * Perception of rotation amplitude and duration: Participants will be seated on a rotating chair, in complete darkness with noise-cancelling headphones. Participant will have to estimate the duration and the amplitude of rotations of the chair. * Perceptual time constant: Participants will be seated on a rotating chair, in complete darkness, with a mask over their eyes and noise-cancelling headphones. After each chair rotation, participants will have to turn a crank every time the chair stops and reproduce their sensation of rotation in terms of direction (left or right) and intensity.
Participants will wear a virtual reality headset which allows them to be immersed in a virtual room similar in appearance to the one they are in. They will sit on a stool and hold a joystick in their hand. An avatar seen from behind, also sitting on a stool, will be presented in the centre of the virtual room approximately 2 m from them. The experimenter will touch several areas of the participant's back, over his clothes, with the end of the joystick. This movement will be reproduced by the virtual joystick in contact with the avatar's back, in two conditions: the synchronous condition, and the asynchronous condition. After 2 min of stimulation, participants will perform a mental imagery task: a ball in the background of the virtual scene will roll towards them. After 3'', a black screen will appear and participants will have to imagine that the ball keeps moving towards them at the same speed. They will have to press the trigger when they think the ball has reached their level.
The imaging evaluation will include an acquisition of anatomical images of the brain in its entirety and centred on the hippocampus.; and T2\*-weighted images sensitive to the blood-oxygen-level-dependent (BOLD) effect to assess functional brain activation during cognitive tasks and functional brain connectivity during rest. For the functional activation sequences, three activation tasks will be performed, each lasting approximately 5 minutes: a mental rotation task, a time estimation task, and a prediction task. These acquisitions will be combined with a collection of cardiorespiratory variables: respiratory movements and plethysmography. These signals will be used in the pre-processing of the functional MRI to remove physiological noise from the BOLD signal.
Deviation distance (Fukuda stepping test)
During the Fukuda stepping test, subjects are asked to take 50 steps on the spot, on a mat, with their eyes closed and their arms outstretched in front of them. Deviation distance is measured in cm.
Time frame: Assessment of postural stability and active motion perception is completed once, during about 30 minutes
Deviation angle (Fukuda stepping test)
During the Fukuda stepping test, subjects are asked to take 50 steps on the spot, on a mat, with their eyes closed and their arms outstretched in front of them. Deviation angle is measured in degrees.
Time frame: Assessment of postural stability and active motion perception is completed once, during about 30 minutes
Hippocampal volume
Images of hippocampus are acquired by MRI
Time frame: MRI exam is completed once, during about 1 hour
Brain activation during functional tasks
Images of the brain when participants are performing cognitive tasks (mental rotation task, prediction task) are acquired by functional magnetic resonance imaging (fMRI)
Time frame: MRI exam is completed once, during about 1 hour
Center of pressure (CoP) standard deviation - Anteroposterior
Stabilometric data: Standard deviation of the CoP position in the anteroposterior axis (in mm)
Time frame: Posturography is assessed once, during about 30 minutes.
Center of pressure (CoP) standard deviation - Mediolateral
Stabilometric data: Standard deviation of the CoP position in the mediolateral axis (in mm)
Time frame: Posturography is assessed once, during about 30 minutes.
Duration of the word reading in the congruent condition
Stroop color and word test : time spent to read the words in the congruent condition (in seconds)
Time frame: Cognitive functions are assessed once, during about 30 minutes
Duration of the colour naming
Stroop color and word test : time spent to name the colours (in seconds)
Time frame: Cognitive functions are assessed once, during about 30 minutes
Duration of the word reading in the incongruent condition
Stroop color and word test : time spent to read the words in the incongruent condition (in seconds)
Time frame: Cognitive functions are assessed once, during about 30 minutes
Trail making test part A
Paper and pencil Trail Making Test: Time spent by the subject to draw a line between numbers from 1 to 25 (in seconds)
Time frame: Cognitive functions are assessed once, during about 30 minutes
Trail making test part B
Paper and pencil Trail Making Test: Time spent by the subject to draw a line between numbers and letters (1-A, 2-B, etc.) (in seconds)
Time frame: Cognitive functions are assessed once, during about 30 minutes
Digit span during dual-task
Number of digits correctly recalled during the Baddeley's dual-task
Time frame: Cognitive functions are assessed once, during about 30 minutes
Number of sequences correctly recalled
In the simple and dual conditions of the Baddeley's dual-task
Time frame: Cognitive functions are assessed once, during about 30 minutes
Spatial span
Number of blocks correctly recalled during the Corsi task
Time frame: Cognitive functions are assessed once, during about 30 minutes
Estimation of the duration of rotation
During the Perception of the amplitude and duration of rotations task, subjects seated in a rotating chair are asked to estimate the duration of the rotations (in seconds)
Time frame: Perception of the amplitude and duration of rotations task is completed once, during about 30 minutes.
Estimation of the amplitude of rotation
During the Perception of the amplitude and duration of rotations task, subjects seated in a rotating chair are asked to estimate the amplitude of the rotations (in degree)
Time frame: Perception of the amplitude and duration of rotations task is completed once, during about 30 minutes.
Deviation distance (Triangle completion task)
During the triangle completion task, the participant will wear a blindfold and a noise-cancelling headphones. Guided by the experimenter, who will hold them by the shoulders, they will walk along the first two sides of a triangle. The participant will then have to turn on their own and walk along the third side to get back to the starting point. The deviation distance is measured in cm.
Time frame: Assessment of postural stability and active motion perception is completed once, during about 30 minutes
Deviation angle (Triangle completion task)
During the triangle completion task, the participant will wear a blindfold and a noise-cancelling headphones. Guided by the experimenter, who will hold them by the shoulders, they will walk along the first two sides of a triangle. The participant will then have to turn on their own and walk along the third side to get back to the starting point. The deviation angle is measured in degree.
Time frame: Assessment of postural stability and active motion perception is completed once, during about 30 minutes