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Visual influences on vestibular compensation and postural control

Hafström, Anna LU (2007)
Abstract (Swedish)
Popular Abstract in Swedish

Interaktionen mellan syn- och balanssinne för orienterings- och balansförmåga studerades hos friska försökspersoner, alkoholpåverkade friska försökspersoner och personer med en väldefinierad, ensidig vestibulär skada: translabyrintär vestibulär nervavskärning pga vestibularisschwannom. Balansförmåga i stående studerades med posturografi. Visuo-vestibulär orienteringsförmåga undersöktes med test av subjektiv visuell horisont och vertikal som är ett enkelt test där den testade personen i mörker ska ställa in en svagt lysande linje till upplevd horisont respektive vertikal. Testet har hög samstämmighet med direkta mått på okulär torsion (ögonbottenfoto) och avspeglar därmed, åtminstone delvis,... (More)
Popular Abstract in Swedish

Interaktionen mellan syn- och balanssinne för orienterings- och balansförmåga studerades hos friska försökspersoner, alkoholpåverkade friska försökspersoner och personer med en väldefinierad, ensidig vestibulär skada: translabyrintär vestibulär nervavskärning pga vestibularisschwannom. Balansförmåga i stående studerades med posturografi. Visuo-vestibulär orienteringsförmåga undersöktes med test av subjektiv visuell horisont och vertikal som är ett enkelt test där den testade personen i mörker ska ställa in en svagt lysande linje till upplevd horisont respektive vertikal. Testet har hög samstämmighet med direkta mått på okulär torsion (ögonbottenfoto) och avspeglar därmed, åtminstone delvis, otolitorganens funktion.



Sammanfattningsvis visar avhandlingsarbetet att samspelet mellan syn- och balanssinne och grad av synberoende är viktiga faktorer vid utredning och rehabilitering av patienter med vestibulära skador och balansproblem. För första gången har ett test som avspeglar otolitorganens funktion applicerats på en stor, konsekutiv grupp patienter med väldefinierade ensidiga vestibulära skador. Visuell information kan ge missledande signaler för rumsuppfattning och uppfattning av subjektiv visuell horisont och vertikal. I avhandlingen visas för första gången att subkliniska, ensidiga vestibulära skador och också alkoholberusning kan leda till asymmetrisk påverkan av visuo-spatial förmåga. Fynden tyder på att det är lättare att misstolka visuell information vid vestibulära skador, stigande ålder och alkoholpåverkan och möjligen kan detta bidra till en ökad olycksfallsrisk. God syninformation är viktig för att förebygga fallolyckor och vid rehabilitering av patienter med balansproblem. (Less)
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.

... (More)
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. (Less)
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author
opponent
  • Professor Ygge, Jan, Inst. för Klinisk Neurovetenskap (CNS), sektionen för Ögon och Syn, Sankt Eriks Ögonsjukhus, Karolin
organization
publishing date
type
Thesis
publication status
published
subject
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
pages
122 pages
publisher
Department of Otorhinolaryngology, Lund University
defense location
"Kulturanatomen", Inst. för Kulturvetenskaper, Biskopsgatan 7, Lunds Universitet
defense date
2007-05-12 11:45
ISSN
1652-8220
ISBN
978-91-85559-48-0
language
English
LU publication?
yes
id
f9591db2-f234-4a23-a885-5a844e38b76c (old id 548530)
date added to LUP
2007-09-12 07:45:51
date last changed
2016-09-19 08:44:54
@phdthesis{f9591db2-f234-4a23-a885-5a844e38b76c,
  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).<br/><br>
<br/><br>
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.<br/><br>
<br/><br>
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.<br/><br>
<br/><br>
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.<br/><br>
<br/><br>
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.<br/><br>
<br/><br>
Older patients with a vestibular schwannoma have increased visual dependency and decreased compensation of the SVH and SVV compared to younger patients.<br/><br>
<br/><br>
Alcohol intoxication impairs the ability to use gravitational vestibular cues in SVH and SVV tests, and increases visual field dependence.<br/><br>
<br/><br>
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.},
  author       = {Hafström, Anna},
  isbn         = {978-91-85559-48-0},
  issn         = {1652-8220},
  keyword      = {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},
  language     = {eng},
  pages        = {122},
  publisher    = {Department of Otorhinolaryngology, Lund University},
  school       = {Lund University},
  title        = {Visual influences on vestibular compensation and postural control},
  year         = {2007},
}