Advertisement

Journal of Neurology

, Volume 254, Issue 11, pp 1569–1574 | Cite as

Ocular myasthenia revisited: Insights from pseudo-internuclear ophthalmoplegia

  • S. Khanna
  • K. Liao
  • H. J. Kaminski
  • R. L. Tomsak
  • A. Joshi
  • R. J. Leigh
ORIGINAL COMMUNICATION

Abstract

Ocular myasthenia can mimic central disorders of eye movements. We compared horizontal saccades in two patients with myasthenia gravis who presented as pseudo-internuclear ophthalmoplegia (pseudo-INO), two patients with true INO due to multiple sclerosis (MS), and five healthy subjects. In myasthenics, peak velocity of horizontal saccades was similar to, or greater than, controls; in MS patients, adducting saccades were slower than controls. Differences between the peak velocity of abducting and adducting eyes for each saccade were similar to controls for myasthenic pseudo-INO, but greater than controls for true INO. Using the technique of phase-plane analysis, in which eye velocity is plotted against eye position, we found that initial components of abducting and adducting saccades in the myasthenics were as conjugate as controls, even though later components of myasthenic saccades were highly and variably disjunctive. Conversely, phase planes of saccades in true INO showed disjunctive early components of abducting and adducting saccades. Two hypotheses have been offered to account for preservation of fast saccades despite reduced range of eye movements in ocular myasthenia. The first is intrasaccadic neuromuscular fatigue, which is variable over time. Our finding that initial components of saccades were consistently conjugate in the myasthenics gives support to a second hypothesis: selective sparing of pale global fibers, which are important for generating highspeed eye movements, and which are unique amongst extraocular fibers in possessing well developed synaptic folding.

Key words

extraocular muscle saccades diplopia multiple sclerosis (MS) eye movements 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    Barton JJ, Fouladvand M (2000) Ocular aspects of myasthenia gravis. Semin Neurol 20:7–20CrossRefPubMedGoogle Scholar
  2. 2.
    Cogan DG, Yee RD, Gittinger J (1976) Rapid eye movements in myasthenia gravis. I. Clinical observations. Arch Ophthalmol 94:1083–1085PubMedGoogle Scholar
  3. 3.
    Dell'Osso LF, Ayyar DR, Daroff RB, Abel LA (1983) Edrophonium test in Eaton-Lambert syndrome: Quantitative oculography. Neurology 33:1157–1163PubMedGoogle Scholar
  4. 4.
    Donaldson IM (2000) The functions of the proprioceptors of the eye muscles. Philos Trans R Soc Lond B Biol Sci 355:1685–1754CrossRefPubMedGoogle Scholar
  5. 5.
    Flipse JP, Straathof CS, van der SJ, van Leeuwen AF, van Doorn PA, Van der Meche FG, Collewijn H (1997) Binocular saccadic eye movements in multiple sclerosis. J Neurol Sci 148:53–65CrossRefPubMedGoogle Scholar
  6. 6.
    Frohman EM, Frohman TC, O'Suilleabhain P, Zhang H, Hawker K, Racke MK, Frawley W, Phillips JT, Kramer PD (2002) Quantitative oculographic characterisation of internuclear ophthalmoparesis in multiple sclerosis: the versional dysconjugacy index Z score. J Neurol Neurosurg Psychiatry 73:51–55CrossRefPubMedGoogle Scholar
  7. 7.
    Glaser JS (1966) Myasthenic pseudointernuclear ophthalmoplegia. Arch Ophthalmol 75:363–366PubMedGoogle Scholar
  8. 8.
    Hedges TR, Jones A, Stark L, Hoyt WF (1983) Botulin ophthalmoplegia. Clinical and oculographic observations. Arch Ophthalmol 101:211–213PubMedGoogle Scholar
  9. 9.
    Hughes BW, Kusner LL, Kaminski HJ (2006) Molecular architecture of the neuromuscular junction. Muscle and Nerve 33:445–461CrossRefPubMedGoogle Scholar
  10. 10.
    Hughes BW, Moro De Casillas ML, Kaminski HJ (2005) Pathophysiology of myasthenia gravis. Seminars in Neurology 24:21–30CrossRefGoogle Scholar
  11. 11.
    Kusner LL, Puwanant AA, Kaminski HJ (2006) Ocular myasthenia: Diagnosis, treatment, and pathogenesis. The Neurologist 12:231–239CrossRefPubMedGoogle Scholar
  12. 12.
    Martin AR (1994) Amplification of neuromuscular transmission by postjunctional folds. Proceeding of the Royal Society of London: Biological Sciences 258:321–326Google Scholar
  13. 13.
    Porter NC, Salter BC (2005) Ocular Myasthenia Gravis. Curr Treat Options Neurol 7:79–88CrossRefPubMedGoogle Scholar
  14. 14.
    Ramat S, Somers JT, Das VE, Leigh RJ (1999) Conjugate ocular oscillations during shifts of the direction and depth of visual fixation. Invest Ophthalmol Vis Sci 40:1681–1686PubMedGoogle Scholar
  15. 15.
    Scott AB, Collins CC (1973) Division of labor in human extraocular muscle. Arch Ophthalmol 90:319–322PubMedGoogle Scholar
  16. 16.
    Spencer RF, McNeer KW (1987) Botulinum paralysis of adult monkey extraocular muscle: structural alterations in the orbital, singly innervated muscle fibers. Arch Ophthalmol 105:1703–1711PubMedGoogle Scholar
  17. 17.
    Spencer RF, Porter JD (2006) Biological organization of the extraocular muscles. Prog Brain Res 151:33–79Google Scholar
  18. 18.
    Stahl JS, Averbuch-Heller L, Remler BF, Leigh RJ (1998) Clinical evidence of extraocular muscle fiber-type specificity of botulinum toxin. Neurology 51:1093–1099PubMedGoogle Scholar
  19. 19.
    Yee RD, Cogan DG, Zee DS, Baloh RW, Honrubia V (1976) Rapid eye movements in myasthenia gravis. II. Electro-oculographic analysis. Arch Ophthalmol 94:1465–1472PubMedGoogle Scholar

Copyright information

© Steinkopff-Verlag 2007

Authors and Affiliations

  • S. Khanna
    • 1
  • K. Liao
    • 2
  • H. J. Kaminski
    • 1
  • R. L. Tomsak
    • 1
  • A. Joshi
    • 2
  • R. J. Leigh
    • 1
    • 2
    • 3
  1. 1.Daroff-Dell'Osso Laboratory, Dept. of NeurologyVeterans Affairs Medical Center and University Hospitals Case Western Reserve UniversityCleveland
  2. 2.Daroff-Dell’Osso Laboratory, Dept. of Biomedical EngineeringVeterans Affairs Medical Center and University Hospitals Case Western Reserve UniversityCleveland
  3. 3.Dept. of NeurologyVeterans Affairs Medical Center and University Hospitals Case Western Reserve UniversityCleveland

Personalised recommendations