Damaged Vestibular System Clinical Trial
Official title:
Spatial Orientation and Vestibular Function in Patients With Acute or Chronic Unilateral Vestibular Deficits and in Patients With Bilateral Vestibular Deficits
Spatial orientation is achieved through central integration of various sensory inputs and
prior knowledge in a statistically optimal way based on the reliability of the different
signals. When upright, the subjective visual vertical (SVV) is accurate and precise in
healthy human subjects. However, when roll-tilted, both systematic physiologic, roll-angle
dependent errors (termed A- und E-effect) and a decrease in precision of SVV estimates have
been described. In case of a sudden unilateral vestibular deficit (UVD) a significant
imbalance between the two vestibular organs occurs at the level of the vestibular nuclei,
disrupting the percept of vertical. The most frequent cause for such a unilateral vestibular
deficit is an inflammation of the vestibular nerve by viral infection, termed vestibular
neuritis (VN). While in the acute stage these patients are usually immobilized due to the
severity of symptoms, recovery is overall good and most patients return to their daily
activities within a few weeks. Central compensation is considered the most important
contributor to recovery in these patients, while recovery of the damaged vestibular nerve
occurs only in a minority of cases. While acute VN presents with sudden UVD, bilateral
vestibular deficits (BVD) typically evolve more slowly and re-sult in distinct complaints.
The percept of vertical can be quantified by assessing the subjective visual vertical or SVV,
which is usually done by letting subjects adjust a luminous line along perceived direction of
gravity. Modifications of this paradigm which are independent from retinal input are e.g.
adjustments of a rod along perceived vertical in complete darkness (termed subjective haptic
vertical or SHV) and self-alignments along perceived vertical (subjective postural vertical
or SPV) and perceived horizontal (subjective postural horizontal or SPH) in complete
darkness. Previous research has proposed no unified percept of vertical as errors assessed in
different domains (visual, haptic, postural) were diverging in patients with acute UVD. While
errors were profound for the SVV, the SPV remained accurate.
Here the investigators aim to quantify verticality perception in patients with either acute
or chronic UVD and patients with BVD both in upright and roll-tilted positions. Specifically,
the investigators will use different paradigms to address the ques-tion whether there is a
unified percept of vertical and how a bias in this percept changes over time.
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