Quantitative oculographic characterisation of internuclear ophthalmoparesis in multiple sclerosis

The versional dysconjugacy index Z score

Elliot Frohman, T. C. Frohman, Padraig E O'Suilleabhain, H. Zhang, K. Hawker, M. K. Racke, W. Frawley, J. T. Phillips, P. D. Kramer

Research output: Contribution to journalArticle

42 Citations (Scopus)

Abstract

Background: There is a poor correlation between multiple sclerosis disease activity, as measured by magnetic resonance imaging, and clinical disability. Objective: To establish oculographic criteria for the diagnosis and severity of internuclear ophthalmoparesis (INO), so that future studies can link the severity of ocular dysconjugacy with neuroradiological abnormalities within the dorsomedial brain stem tegmentum. Methods: The study involved 58 patients with multiple sclerosis and chronic INO and 40 normal subjects. Two dimensional infrared oculography was used to derive the versional dysconjugacy index (VDI)-the ratio of abducting to adducting eye movements for peak velocity and acceleration. Diagnostic criteria for the diagnosis and severity of INO were derived using a Z score and histogram analysis, which allowed comparisons of the VDI from multiple sclerosis patients and from a control population. Results: For a given saccade, the VDI was typically higher for acceleration v velocity, whereas the Z scores for velocity measures were always higher than values derived from comparable acceleration VDI measures; this was related to the greater variability of acceleration measures. Thus velocity was a more reliable measure from which to determine Z scores and thereby the criteria for INO and its level of severity. The mean (SD) value of the VDI velocity derived from 40 control subjects was 0.922 (0.072). The highest VDI for velocity from a normal control subject was 1.09, which was 2.33 SD above the normal control mean VDI. We therefore chose 2 SD beyond this value (that is, a Z score of 4.33) as the minimum criterion for the oculographic confirmation of INO. Of patients thought to have unilateral INO on clinical grounds, 70% (16/23) were found to have bilateral INO on oculographic assessment. Conclusions: INO can be confirmed and characterised by level of severity using Z score analysis of quantitative oculography. Such assessments may be useful for linking the level of severity of a specific clinical disability with neuroradiological measures of brain tissue pathology in multiple sclerosis.

Original languageEnglish (US)
Pages (from-to)51-55
Number of pages5
JournalJournal of Neurology Neurosurgery and Psychiatry
Volume73
Issue number1
DOIs
StatePublished - 2002

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Ophthalmoplegia
Multiple Sclerosis
Saccades
Eye Movements
Brain Stem
Magnetic Resonance Imaging
Pathology
Brain

ASJC Scopus subject areas

  • Neuropsychology and Physiological Psychology
  • Neuroscience(all)
  • Psychiatry and Mental health

Cite this

Quantitative oculographic characterisation of internuclear ophthalmoparesis in multiple sclerosis : The versional dysconjugacy index Z score. / Frohman, Elliot; Frohman, T. C.; O'Suilleabhain, Padraig E; Zhang, H.; Hawker, K.; Racke, M. K.; Frawley, W.; Phillips, J. T.; Kramer, P. D.

In: Journal of Neurology Neurosurgery and Psychiatry, Vol. 73, No. 1, 2002, p. 51-55.

Research output: Contribution to journalArticle

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abstract = "Background: There is a poor correlation between multiple sclerosis disease activity, as measured by magnetic resonance imaging, and clinical disability. Objective: To establish oculographic criteria for the diagnosis and severity of internuclear ophthalmoparesis (INO), so that future studies can link the severity of ocular dysconjugacy with neuroradiological abnormalities within the dorsomedial brain stem tegmentum. Methods: The study involved 58 patients with multiple sclerosis and chronic INO and 40 normal subjects. Two dimensional infrared oculography was used to derive the versional dysconjugacy index (VDI)-the ratio of abducting to adducting eye movements for peak velocity and acceleration. Diagnostic criteria for the diagnosis and severity of INO were derived using a Z score and histogram analysis, which allowed comparisons of the VDI from multiple sclerosis patients and from a control population. Results: For a given saccade, the VDI was typically higher for acceleration v velocity, whereas the Z scores for velocity measures were always higher than values derived from comparable acceleration VDI measures; this was related to the greater variability of acceleration measures. Thus velocity was a more reliable measure from which to determine Z scores and thereby the criteria for INO and its level of severity. The mean (SD) value of the VDI velocity derived from 40 control subjects was 0.922 (0.072). The highest VDI for velocity from a normal control subject was 1.09, which was 2.33 SD above the normal control mean VDI. We therefore chose 2 SD beyond this value (that is, a Z score of 4.33) as the minimum criterion for the oculographic confirmation of INO. Of patients thought to have unilateral INO on clinical grounds, 70{\%} (16/23) were found to have bilateral INO on oculographic assessment. Conclusions: INO can be confirmed and characterised by level of severity using Z score analysis of quantitative oculography. Such assessments may be useful for linking the level of severity of a specific clinical disability with neuroradiological measures of brain tissue pathology in multiple sclerosis.",
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T2 - The versional dysconjugacy index Z score

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AU - Frohman, T. C.

AU - O'Suilleabhain, Padraig E

AU - Zhang, H.

AU - Hawker, K.

AU - Racke, M. K.

AU - Frawley, W.

AU - Phillips, J. T.

AU - Kramer, P. D.

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