Botulinum Toxin for Essential Tremor of the Voice With Multiple Anatomical Sites of Tremor: A Crossover Design Study of Unilateral Versus Bilateral Injection

Authors

  • Paul Warrick MD,

    1. Department of Otolaryngology, University Health Network, University of Toronto, Toronto, Ontario, Canada
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  • Christopher Dromey PhD,

    1. Department of Otolaryngology, University Health Network, University of Toronto, Toronto, Ontario, Canada
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  • Jonathan C. Irish MD, MSc, FRCSC, FACS,

    Corresponding author
    • Jonathan C. Irish, MD, Princess Margaret Hospital, Room 3-952, University Health Network, Toronto, Ontario M5G 2M9, Canada.
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  • Lisa Durkin MSc,

    1. Department of Speech-Language Pathology, University Health Network, University of Toronto, Toronto, Ontario, Canada
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  • Anthony Pakiam MD, FRCPC,

    1. Division of Neurology, Toronto General Hospital/Toronto Western Hospital, University Health Network, University of Toronto, Toronto, Ontario, Canada
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  • Anthony Lang MD, FRCPC

    1. Division of Neurology, Toronto General Hospital/Toronto Western Hospital, University Health Network, University of Toronto, Toronto, Ontario, Canada
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  • Presented in part at the 52nd Annual Meeting of the Canadian Society of Otolaryngology—Head and Neck Surgery, Montreal, Quebec, Canada, June 14–17, 1998.

    Funded in part through the Spasmodic Dysphonia Research Fund, The Toronto General Hospital, University Health Network, a Burroughs-Wellcome Medical Research Council Scholarship, and a Center of Excellence Grant from the National Parkinson Foundation in Miami.

Abstract

Objectives/Hypothesis To evaluate the relative efficacy of unilateral and bilateral injections of botulinum toxin injection (BOTOX) in the treatment of essential tremor of the voice (ETV).

Study Design Prospective open-label crossover study.

Methods Patients referred to the Neurolaryngology Clinic at Toronto General Hospital with a diagnosis of ETV were eligible for the study. Patients were sequentially assigned to receive BOTOX as either a bilateral 2.5-U or a unilateral 15-U electromyography-guided injection, followed by the alternative injection 16 to 18 weeks later. Acoustic, aerodynamic, and nasopharyngoscopic data were collected approximately 2, 6, 10, and 16 weeks after each injection. Patients were asked to provide a perceptual evaluation of BOTOX effects at the conclusion of the study.

Results Three of 10 patients demonstrated an objective reduction in tremor severity with bilateral injection, and 2 of 9 with unilateral injection. However, 8 of 10 patients wished to be re-injected at the conclusion of the study. A reduction in vocal effort appeared to be coincident with reduction in laryngeal airway resistance after BOTOX injection.

Conclusions Using objective acoustic measures, only a small proportion of patients achieved benefit from BOTOX injection for ETV. However, a majority of patients in our study benefited from a subjective reduction in vocal effort that may have been attributable to reduced laryngeal airway resistance.

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