Consequence of Unilateral Vestibular Loss on Visual Abilities
Condition: Vestibular Schwannoma; Visual Impairment; Vestibular Meniere Syndrome
MeSH terms: Neurilemmoma; Neuroma, Acoustic; Meniere Disease; Vision Disorders; Vision, Low
Study type: Interventional

Summary: 
      Unilateral vestibular lesions are frequent and disabling pathologies causing a set of
      oculomotor, postural and perceptual symptoms. These symptoms reduce over time according to a
      vestibular compensation. However, vestibular compensation should be considered as a set of
      sub-processes whose duration and recovery level differ. Indeed, after a unilateral vestibular
      loss, some functions remain asymmetrical as a long-term effect, and these disorders may be
      observed among patients with no functional complaints. Balance disorders may persist in some
      patients.

      The equilibration consists in handling real-time a considerable amount of information coming
      from the environment and the subject himself, allowing an adaptation of the position and
      movements of his body to satisfy the needs of posture, balance and orientation. This
      information comes mainly from the vision, the vestibule and the somesthesic system. It is
      pre-treated and harmonized in the brainstem, before being transmitted to the higher brain
      centres. Brain centers thus learn about peripheral conditions. According to these and the
      project of the movement, brain centers address in response orders to ophtalmological and
      motor effectors ensuring look, posture and balance to be provided. The eye is a cornerstone
      of the balancing system through the retina, an environmental sensor, and its extraocular
      muscles, effectors of the system.

      The aim of this study is to assess the effects of acute unilateral vestibular loss on visual
      abilities evaluated by orthoptic balance in patients who presented acute unilateral
      vestibular loss by surgical deafferentation (removal of vestibular schwannoma, vestibular
      neurotomy or surgical labyrinthectomy for Meniere's disease), during the early phase and
      decline of vestibular compensation.

      Our secondary objective is to evaluate the effect of a pre-existing anomaly of the visual
      abilities evaluated by orthoptic assessment on the vestibular compensation capacities.

      All in all, this study seems crucial to improve the management of patients with unilateral
      vestibular dysfunction and contribute to improving their clinical management.

      As a standardized management of these patients, an audio-vestibular evaluation will be
      performed before surgery (-1D), after acute unilateral vestibular loss at the early stage
      (+7D), and then after vestibular compensation (+2M) as well as an orthoptic evaluation. A
      good tolerance of the orthoptic evaluation is expected in this surgical context.
    

Detailed description: 
      Unilateral vestibular lesions are frequent and disabling pathologies, with significant
      psychological impacts, as well as on the socio-professional and daily life of the affected
      subjects. Furthermore, socio-economic consequences have to be considered.

      The involvement of the vestibular system in the stabilization control of the look, the
      eye-head coordination, posture, locomotion and perception of verticality is widely
      recognized. Therefore, the unilateral vestibular diseases cause a set of oculomotor, postural
      and perceptual symptoms. These symptoms reduce over time according to a process known as
      vestibular compensation. However, vestibular compensation should be considered as a set of
      sub-processes whose duration and recovery level differ. Indeed, after a unilateral vestibular
      loss, some functions remain asymmetrical as a long-term effect, and these disorders may be
      observed among patients with no functional complaints. Balance disorders may persist in some
      patients.

      The equilibration consists in handling real-time a considerable amount of information coming
      from the environment and the subject himself, allowing an adaptation of the position and
      movements of his body to satisfy the needs of posture, balance and orientation. This
      information comes mainly from the vision, the vestibule and the somesthesic system. It is
      pre-treated and harmonized in the brainstem, before being transmitted to the higher brain
      centres. Brain centres thus learn about peripheral conditions. According to these and the
      project of the movement, brain centers address in response orders to ophtalmological and
      motor effectors ensuring look, posture and balance to be provided. The eye is a cornerstone
      of the balancing system through the retina, an environmental sensor, and its extraocular
      muscles, effectors of the system.

      The aim of this study is to assess the effects of acute unilateral vestibular loss on visual
      abilities evaluated by orthoptic balance in patients who presented acute unilateral
      vestibular loss by surgical deafferentation (removal of vestibular schwannoma, vestibular
      neurotomy or surgical labyrinthectomy for Meniere's disease), during the early phase and
      decline of vestibular compensation.

      Our secondary objective is to evaluate the effect of a pre-existing anomaly of the visual
      abilities evaluated by orthoptic assessment on the vestibular compensation capacities.

      All in all, this study seems crucial to improve the management of patients with unilateral
      vestibular dysfunction and contribute to improving their clinical management by prescribing
      an appropriate rehabilitation.

      As a standardized management of these patients, an audio-vestibular evaluation (clinical ENT
      examination, pure tone and speech audiometry, videonystagmography, vestibular evoked myogenic
      potentials, Posturography, Vertical Visual Subjective, quality of life by Dizziness Handicap
      Inventory) will be performed before surgery (-1D), after acute unilateral vestibular loss at
      the early stage (+7D), and then after vestibular compensation (+2M).

      An orthoptic evaluation will be performed during 30 min and the audio vestibular evaluation
      will be carried out at the same time. A good tolerance of the orthoptic evaluation is
      expected in this surgical context.
    

Intervention name(s): orthoptic balance
Intervention type(s): Diagnostic Test
Intervention description(s): Measurement of visual acuity by far: Monocular measurement, right eye, left eye and binocular Measurement of visual acuity closely: Monocular measurement, right eye, left eye and binocular Corneal reflection method or Hirschberg: Analysis of the corneal reflection after fixation of a point of fixation of light from a distance, then from near.
Cover-Test: Study of the restitution movement following the fixation of the fixation point
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Other