Long-term depression-like plasticity of the blink reflex for the treatment of blepharospasm

Authors

  • Gottfried Kranz MD,

    Corresponding author
    1. Department of Neurology, Medical University of Vienna, Wien, Austria
    • Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
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  • Ejaz A. Shamim MD, MS,

    1. Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
    2. Department of Neurology, Mid-Atlantic Permanente Research Institute of the Mid-Atlantic Permanente Medical Group, Rockville, Maryland, USA
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  • Peter T. Lin MD,

    1. Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
    2. Department of Neurology, Santa Clara Valley Medical Center, San Jose, California, USA
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  • George S. Kranz MSc,

    1. Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria
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  • Mark Hallett MD

    1. Human Motor Control Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA
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  • Funding agencies: This work was supported by the National Institutes of Health/National Institute for Neurological Disorders and Stroke Human Motor Control Section and the Max Kade Foundation (New York, New York, USA; to G.K.).

  • Relevant conflicts of interest/financial disclosures: Nothing to report.

  • Full financial disclosures and author roles may be found in the online version of this article.

Correspondence to: Dr. Gottfried Kranz, Department of Neurology, Medical University of Vienna, Waehringer Guertel 18-20, A-1090 Vienna, Austria; gottfried.kranz@meduniwien.ac.at

ABSTRACT

Our previous work showed a beneficial therapeutic effect on blepharospasm using slow repetitive transcranial magnetic stimulation, which produces a long-term depression (LTD)-like effect. High-frequency supraorbital electrical stimulation, asynchronous with the R2 component of the blink reflex, can also induce LTD-like effects on the blink reflex circuit in healthy subjects. Patients with blepharospasm have reduced inhibition of their blink recovery curves; therefore, a LTD-like intervention might normalize the blink reflex recovery (BRR) and have a favorable therapeutic effect. This is a randomized, sham-controlled, observer-blinded prospective study. In 14 blepharospasm patients, we evaluated the effects of high-frequency supraorbital stimulation on three separate treatment days. We applied 28 trains of nine stimuli, 400 Hz, either before or after the R2 or used sham stimulation. The primary outcome was the blink rate, number of spasms rated by a blinded physician and patient rating before, immediately after and 1 hour after stimulation while resting, reading, and talking; secondary outcome was the BRR. Stimulation “before” and “after” the R2 both showed a similar improvement as sham stimulation in physician rating, but patients felt significantly better with the before condition. Improvement in recovery of the blink reflex was noted only in the before condition. Clinical symptoms differed in the three baseline conditions (resting, reading, and talking). Stimulation before R2 increased inhibition in trigeminal blink reflex circuits in blepharospasm toward normal values and produced subjective, but not objective, improvement. Inhibition of the blink reflex pathway by itself appeared to be insufficient for a useful therapeutic effect. © 2013 Movement Disorder Society

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