Abstract
This thesis aimed to investigate visual-vestibular interactions in healthy subjects and in patients with a well defined unilateral vestibular lesion (vestibular schwannoma before and six months after translabyrinthine surgery).
Visual information is particularly important for balance control during perturbed stance. The physical act of having the eyes open or closed affects motion strategy in postural control. Standing with eyes open in darkness during balance perturbations is initially of disadvantage compared to standing with eyes closed. The postural control system appears to expect visual feedback information when eyes are open, which delays a re-weighting to vestibular and proprioceptive information.
A pathologic deviation of the subjective visual horizontal (SVH) and vertical (SVV) toward the lesioned side is still present six months after unilateral vestibular deafferentation. There is great SVH and SVV variability between patients which proposes an idiosyncrasy in the compensation of graviceptive vestibular tone imbalance.
Postural sway is not related to the deviation of the SVH and SVV which indicates that utriculo-ocular compensation is not related to postural compensation.
Patients with a unilateral vestibular schwannoma are not more visually field dependent than healthy subjects are, but have an increased ipsilesional deviation in the rod and frame test. This suggests asymmetric visual field dependence, and that the rod and frame test can reveal a hidden vestibular imbalance.
Older patients with a vestibular schwannoma have increased visual dependency and decreased compensation of the SVH and SVV compared to younger patients.
Alcohol intoxication impairs the ability to use gravitational vestibular cues in SVH and SVV tests, and increases visual field dependence.
Visual dependence and visual-vestibular interactions are important factors to consider when investigating and rehabilitating patients with balance disorders. With conflicting gravitational and visual information a re-weighting from a vestibular to a more visual dependency in balance control might increase the risk of misinterpreting the visual information and thus increase the risk of accidents. It is important with good lighting conditions to provide patients with adequate sway referencing visual information.
Visual information is particularly important for balance control during perturbed stance. The physical act of having the eyes open or closed affects motion strategy in postural control. Standing with eyes open in darkness during balance perturbations is initially of disadvantage compared to standing with eyes closed. The postural control system appears to expect visual feedback information when eyes are open, which delays a re-weighting to vestibular and proprioceptive information.
A pathologic deviation of the subjective visual horizontal (SVH) and vertical (SVV) toward the lesioned side is still present six months after unilateral vestibular deafferentation. There is great SVH and SVV variability between patients which proposes an idiosyncrasy in the compensation of graviceptive vestibular tone imbalance.
Postural sway is not related to the deviation of the SVH and SVV which indicates that utriculo-ocular compensation is not related to postural compensation.
Patients with a unilateral vestibular schwannoma are not more visually field dependent than healthy subjects are, but have an increased ipsilesional deviation in the rod and frame test. This suggests asymmetric visual field dependence, and that the rod and frame test can reveal a hidden vestibular imbalance.
Older patients with a vestibular schwannoma have increased visual dependency and decreased compensation of the SVH and SVV compared to younger patients.
Alcohol intoxication impairs the ability to use gravitational vestibular cues in SVH and SVV tests, and increases visual field dependence.
Visual dependence and visual-vestibular interactions are important factors to consider when investigating and rehabilitating patients with balance disorders. With conflicting gravitational and visual information a re-weighting from a vestibular to a more visual dependency in balance control might increase the risk of misinterpreting the visual information and thus increase the risk of accidents. It is important with good lighting conditions to provide patients with adequate sway referencing visual information.
| Original language | English |
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| Qualification | Doctor |
| Awarding Institution |
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| Supervisors/Advisors |
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| Award date | 2007 May 12 |
| Publisher | |
| ISBN (Print) | 978-91-85559-48-0 |
| Publication status | Published - 2007 |
Bibliographical note
Defence detailsDate: 2007-05-12
Time: 11:45
Place: "Kulturanatomen", Inst. för Kulturvetenskaper, Biskopsgatan 7, Lunds Universitet
External reviewer(s)
Name: Ygge, Jan
Title: Professor
Affiliation: Inst. för Klinisk Neurovetenskap (CNS), sektionen för Ögon och Syn, Sankt Eriks Ögonsjukhus, Karolin
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<div class="article_info">A Hafstrom, PA Fransson, M Karlberg, T Ledin and M Magnusson. <span class="article_issue_date">2002</span>. <span class="article_title">Visual influence on postural control, with and without visual motion feedback.</span> <span class="journal_series_title">Acta Otolaryngol</span>, <span class="journal_volume">vol 122</span> <span class="journal_pages">pp 392-7</span>.</div>
<div class="article_info">. <span class="article_issue_date">2004</span>. <span class="article_title">Idiosyncratic compensation of the subjective visual horizontal and vertical in 60 patients after unilateral vestibular deafferentation.</span> <span class="journal_series_title">Acta Otolaryngol</span>, (manuscript)</div>
<div class="article_info">A Hafstrom, PA Fransson, M Karlberg and M Magnusson. <span class="article_issue_date">2004</span>. <span class="article_title">Idiosyncratic compensation of the subjective visual horizontal and vertical in 60 patients after unilateral vestibular deafferentation.</span> <span class="journal_series_title">Acta Otolaryngol</span>, <span class="journal_volume">vol 124</span> <span class="journal_pages">pp 165-71</span>.</div>
<div class="article_info">A Hafstrom, PA Fransson, M Karlberg and M Magnusson. <span class="article_issue_date">2006</span>. <span class="article_title">Subjective visual tilt and lateral instability after vestibular deafferentation.</span> <span class="journal_series_title">Acta Otolaryngol</span>, <span class="journal_volume">vol 126</span> <span class="journal_pages">pp 1176-81</span>.</div>
<div class="article_info">A Hafstrom, PA Fransson, M Karlberg and M Magnusson. <span class="article_issue_date">2004</span>. <span class="article_title">Ipsilesional visual field dependency for patients with vestibular schwannoma.</span> <span class="journal_series_title">Neuroreport</span>, <span class="journal_volume">vol 5;15</span> <span class="journal_pages">pp 2201-4</span>.</div>
<div class="article_info">A Hafstrom, F Modig, M Karlberg and PA Fransson. <span class="article_issue_date">2007</span>. <span class="article_title">Increased visual dependence and otolith dysfunction with alcohol intoxication.</span> <span class="journal_series_title">Neuroreport</span>, <span class="journal_volume">vol 5;18</span> <span class="journal_pages">pp 391-394</span>.</div>
Subject classification (UKÄ)
- Oto-rhino-laryngology
Free keywords
- Otorhinolaryngology
- audiology
- auditive system and speech
- Otorinolaryngologi
- Medicin (människa och djur)
- Vestibular schwannoma
- Alcohol intoxication.
- Medicine (human and vertebrates)
- Vestibular deafferentation
- Visual-vestibular interactions
- Subjective visual horizontal and vertical
- Visual dependence
- Utriculus
- Balance
- Vision
- audiologi
- hörsel- och talorganen
