Objective: To describe the difficulties and limited treatment options for isolated vocal tremor.

Background: Isolated vocal tremor is a unique phenotype of isolated focal tremor defined as tremor of the voice with no signs of dystonia, other tremor, or other focal deficits [1][2]. Currently limited interventions are available for isolated vocal tremor as typical treatments of essential tremor are not generally effective. Current reports and treatments are infrequent and further case series can lead to more treatment options.

Case1: A 68-year-old woman comes for abnormal voice for last 1.5 years. Laryngoscopy showed vocal cord tremor with no signs of dystonia. She had tried primidone, propranolol, gabapentin, and amantadine with no benefit. She underwent botulinum injections (BoNT) with improvement in her tremor.

Case 2: A 73-year-old woman with 6 months of vocal tremor. No sign of dystonia on flexible laryngoscope. She tried propranolol with no benefit. Low dose BoNT did not help with tremor, however higher dose did but she developed dysphagia.

Case 3: A 62-year-old woman with 3-year history of vocal tremulousness. Laryngoscopy was notable for rhythmic tremor of larynx during phonation. She tried primidone and propranolol with no effect. She is now interested in trying BoNT.

Case 4: A 65-year-old female with 5-year period of difficulty with phonation. Exam and laryngoscope with laryngeal tremor with no dystonia. She tried primidone with no effect. She underwent BoNT with improvement in her vocal tremor and phonation with minimal side effects.

Method: This is a case series.

Results: In our cases vocal tremors were observed on exam with no evidence of spasmodic dysphonia on laryngoscopy and with normal exam and no sign of action tremor in the extremities. Many of the patients had tried primidone, propranolol, gabapentin, or amantadine with little to no effect. Most underwent BoNT with improvement, though only one patient continued while 2 patients discontinued due to side effects including soft and breathy voice and mild dysphagia.

Conclusion: Isolated vocal tremor is phenomenon with scarce literature but is often distinguished as separate from essential tremor or essential tremor plus disorders. Current literature of phenomenology, pathophysiology, and treatments is limited. Further case studies regarding treatments will help guide understanding of the phenomenon and lead to more targeted therapeutic options.

*5 videos to be included in poster presentation.

References: [1] Bhatia, K.P., Bain, P., Bajaj, N., Elble, R.J., Hallett, M., Louis, E.D., Raethjen, J., Stamelou, M., Testa, C.M., Deuschl, G. and (2018), Consensus Statement on the classification of tremors. from the task force on tremor of the International Parkinson and Movement Disorder Society. Mov Disord., 33: 75-87. https://doi.org/10.1002/mds.27121
[2] Torrecillas V, Dwenger K, Barkmeier-Kraemer JM. Classification of vocal tremor using updated consensus-based tremor classification criteria. Laryngoscope Investig Otolaryngol. 2021;6(2):261-276. Published 2021 Mar 9. doi:10.1002/lio2.544

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