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Clinical usefulness of the rotatory, caloric, and vestibular evoked myogenic potential test

Leen Maes UGent (2010)
abstract
Examination of dizzy patients is often diagnostically challenging, because of the complexity of the vestibular system and its interaction with other sensory systems. A thorough history, physical examination and performance of vestibular screening tests often result in a probable diagnosis. To confirm this diagnosis or in cases where no precise diagnosis can be found, extensive vestibular laboratory investigations are necessary. Moreover, these tests are of great importance to further define and specify the extent, location, and side of the vestibular pathology, and to follow up central and/or peripheral recovery processes. The primary objective of this thesis was to investigate the clinical usefulness of the rotatory, caloric, and vestibular evoked myogenic potential (VEMP) test. This goal was achieved through five different research aims: test protocols were developed for the different laboratory techniques, normative data were determined in young adults, the reliability or variability was examined, the influence of a possible age effect was scrutinized, and the clinical relevance of the rotatory, caloric, and VEMP test was investigated in a patient population. A rotational protocol was developed consisting of ten rotations distributed over three different rotational paradigms, i.e. five sinusoidal harmonic acceleration tests (SHAT), a pseudorandom rotation test (PRRT), and four velocity step tests (VST). Normative data were calculated for each of these ten rotations and a high reliability was obtained for the SHAT, PRRT, and VST gain values, SHAT phase and asymmetry values, and for the VST time constant parameters. For the caloric test, irrigation with water as a stimulus was compared with air insufflations, resulting in the determination of normative data for both techniques. The water irrigation technique was preferred as standard irrigation medium, based on higher slow component velocity (SCV) values, a smaller variability, and a better subject tolerance. Normative data were also calculated for the VEMP technique. Good to excellent reliability was obtained for all response parameters with the latency and threshold presenting the highest reliability compared to the amplitude parameters, presenting the lowest reliability for the asymmetry ratio. The investigation of age effects on the laboratory techniques showed no age trends for the SHAT and VST test, and only subtle decreasing gain values for the PRRT. For the caloric test, increasing SCV and fixation index values with advancing age were demonstrated, being more pronounced for the warm irrigations. The largest age trends were detected with the VEMP, showing decreasing amplitudes, increasing thresholds, and decreasing N1 latencies with increasing age. Therefore, no separate age-related normative data were needed for the SHAT and VST, in contrast to age-specific normative data for several response parameters for the PRRT, caloric, and VEMP test. The clinical usefulness of each of those techniques was investigated in a patient population diagnosed with a unilateral peripheral vestibular pathology. Investigation of the diagnostic capacity of the rotatory paradigms resulted in a limitation of the formerly used rotational test protocol to only three SHAT rotations, being a clinically more feasible protocol. Comparison of the three laboratory techniques for the detection of a unilateral pathology revealed the highest diagnostic capacity for the caloric test, with high sensitivity and specificity values. However, the slowest SHAT rotation appeared more sensitive and the VEMP technique more specific compared to the caloric test. Because of these sensitivity – specificity relations, the different approach of the rotatory and caloric test to examine the same parts of the vestibular system, and because of the investigation of different parts of the vestibular system with the VEMP technique, the results of all three tests should be taken into account to obtain an adequate function evaluation of the vestibular system. The rotatory phase parameter, the unilateral weakness parameter of the caloric test, and the presence or absence of VEMP responses in combination with the asymmetry ratio were clinically the most relevant response parameters. In conclusion, this research work resulted in the construction of a set of laboratory specific age-related normative data, focussed on the most reliable and clinically most important response parameters, allowing for a more accurate test result interpretation of dizzy patients in the future.
Please use this url to cite or link to this publication:
author
promoter
UGent and UGent
organization
year
type
dissertation
publication status
published
subject
pages
243 pages
publisher
Ghent University. Faculty of Medicine and Health Sciences
place of publication
Ghent, Belgium
defense location
Gent : UZ (auditorium E)
defense date
2010-05-25 17:30
language
English
UGent publication?
yes
classification
D1
additional info
dissertation consists of copyrighted materials
copyright statement
I have transferred the copyright for this publication to the publisher
id
1093335
handle
http://hdl.handle.net/1854/LU-1093335
date created
2011-01-02 16:58:10
date last changed
2017-01-16 10:37:57
@phdthesis{1093335,
  abstract     = {Examination of dizzy patients is often diagnostically challenging, because of the complexity of the vestibular system and its interaction with other sensory systems. A thorough history, physical examination and performance of vestibular screening tests often result in a probable diagnosis. To confirm this diagnosis or in cases where no precise diagnosis can be found, extensive vestibular laboratory investigations are necessary. Moreover, these tests are of great importance to further define and specify the extent, location, and side of the vestibular pathology, and to follow up central and/or peripheral recovery processes. 
The primary objective of this thesis was to investigate the clinical usefulness of the rotatory, caloric, and vestibular evoked myogenic potential (VEMP) test. This goal was achieved through five different research aims: test protocols were developed for the different laboratory techniques, normative data were determined in young adults, the reliability or variability was examined, the influence of a possible age effect was scrutinized, and the clinical relevance of the rotatory, caloric, and VEMP test was investigated in a patient population. 
A rotational protocol was developed consisting of ten rotations distributed over three different rotational paradigms, i.e. five sinusoidal harmonic acceleration tests (SHAT), a pseudorandom rotation test (PRRT), and four velocity step tests (VST). Normative data were calculated for each of these ten rotations and a high reliability was obtained for the SHAT, PRRT, and VST gain values, SHAT phase and asymmetry values, and for the VST time constant parameters. For the caloric test, irrigation with water as a stimulus was compared with air insufflations, resulting in the determination of normative data for both techniques. The water irrigation technique was preferred as standard irrigation medium, based on higher slow component velocity (SCV) values, a smaller variability, and a better subject tolerance. Normative data were also calculated for the VEMP technique. Good to excellent reliability was obtained for all response parameters with the latency and threshold presenting the highest reliability compared to the amplitude parameters, presenting the lowest reliability for the asymmetry ratio. 
The investigation of age effects on the laboratory techniques showed no age trends for the SHAT and VST test, and only subtle decreasing gain values for the PRRT. For the caloric test, increasing SCV and fixation index values with advancing age were demonstrated, being more pronounced for the warm irrigations. The largest age trends were detected with the VEMP, showing decreasing amplitudes, increasing thresholds, and decreasing N1 latencies with increasing age. Therefore, no separate age-related normative data were needed for the SHAT and VST, in contrast to age-specific normative data for several response parameters for the PRRT, caloric, and VEMP test. 
The clinical usefulness of each of those techniques was investigated in a patient population diagnosed with a unilateral peripheral vestibular pathology. Investigation of the diagnostic capacity of the rotatory paradigms resulted in a limitation of the formerly used rotational test protocol to only three SHAT rotations, being a clinically more feasible protocol. Comparison of the three laboratory techniques for the detection of a unilateral pathology revealed the highest diagnostic capacity for the caloric test, with high sensitivity and specificity values. However, the slowest SHAT rotation appeared more sensitive and the VEMP technique more specific compared to the caloric test. Because of these sensitivity -- specificity relations, the different approach of the rotatory and caloric test to examine the same parts of the vestibular system, and because of the investigation of different parts of the vestibular system with the VEMP technique, the results of all three tests should be taken into account to obtain an adequate function evaluation of the vestibular system. The rotatory phase parameter, the unilateral weakness parameter of the caloric test, and the presence or absence of VEMP responses in combination with the asymmetry ratio were clinically the most relevant response parameters. 
In conclusion, this research work resulted in the construction of a set of laboratory specific age-related normative data, focussed on the most reliable and clinically most important response parameters, allowing for a more accurate test result interpretation of dizzy patients in the future.},
  author       = {Maes, Leen},
  language     = {eng},
  pages        = {243},
  publisher    = {Ghent University. Faculty of Medicine and Health Sciences},
  school       = {Ghent University},
  title        = {Clinical usefulness of the rotatory, caloric, and vestibular evoked myogenic potential test},
  year         = {2010},
}

Chicago
Maes, Leen. 2010. “Clinical Usefulness of the Rotatory, Caloric, and Vestibular Evoked Myogenic Potential Test”. Ghent, Belgium: Ghent University. Faculty of Medicine and Health Sciences.
APA
Maes, Leen. (2010). Clinical usefulness of the rotatory, caloric, and vestibular evoked myogenic potential test. Ghent University. Faculty of Medicine and Health Sciences, Ghent, Belgium.
Vancouver
1.
Maes L. Clinical usefulness of the rotatory, caloric, and vestibular evoked myogenic potential test. [Ghent, Belgium]: Ghent University. Faculty of Medicine and Health Sciences; 2010.
MLA
Maes, Leen. “Clinical Usefulness of the Rotatory, Caloric, and Vestibular Evoked Myogenic Potential Test.” 2010 : n. pag. Print.