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CONCLUSION LBTX is an effective therapy in patients with vocal tremor of all subtypes, including those with vertical and/or horizontal components and those with minor pro fi les of spasmodic dysphonia. Characterization of horizon tal and vertical components is recommended, as injection to both thyroarytenoid and strap muscles in patients with both components can maximize outcomes. BIBLIOGRAPHY 1. Sulica L, Louis ED. Clinical characteristics of essential voice tremor: a study of 34 cases. Laryngoscope 2010;120:516 – 528. 2. Merati A, Heman-Ackah Y, Abaza M, Altman K, Sulica L, Belamowicz S. Common movement disorders affecting the larynx: a report from the Neu rolaryngology Committee of the AAO-HNS. Otolaryngol Head Neck Surg 2005;133:654 – 665. 3. Justicz N, Hapner E, Josephs J, Boone B, Jinnah H, Johns M. Comparative effectiveness of propranolol and botulinum for the treatment of essential voice tremor. Laryngoscope 2015;126:113 – 117. 4. Gurey L, Sinclair C, Blitzer A. A new paradigm for the management of essential vocal tremor with botulinum toxin. Laryngoscope 2013;123: 2497 – 2501. 5. Kaye R, Blitzer A. Chemodenervation of the larynx. Toxins 2017;9:1 – 16. 6. Patel P, Kabagambe E, Starkweather J, et al. Outcomes of onabotulinum toxin a treatment for adductor spasmodic dysphonia and laryngeal tremor. JAMA Otolaryngol Head Neck Surg 2018;144:293 – 299. 7. Barkmeier-Karemer J, Lato A. Development of a speech treatment program for a client with essential vocal tremor. Semin Speech Lang 2011;32: 43 – 57. 8. Barkmeier-Karemer J, Clark H. Speech-language pathology evaluation and management of hyperkinetic disorders affecting speech and swallowing function. Tremor Other Hyperkinet Mov (N Y) 2017;7:489. 9. Nida A, Alston J, Schweinfurth J. Primadone therapy for essential vocal tremor. JAMA Otolaryngol Head Neck Surg 2016;142:117 – 121. 10. Estes C, Sadoughi B, Coleman R, Sarva H, Mauer E, Sulica L. A prospective crossover trial of botulinum toxin chemodenervation versus injection aug mentation for essential voice tremor. Laryngoscope 2018;128:437 – 446. 11. Adler C, Bansberg S, Hentz J, et al. Botulinum toxin type a for treating voice tremor. Arch Neurol 2004;61:1416 – 1420. 12. Van Esch B, Wegner I, Stegeman I, Grolman W. Effect of botulinum toxin and surgery among spasmodic dysphonia patients. Otolaryngol Head Neck Surg 2017;156:238 – 254. 13. Wolraich D, Vasile Marchis-Crisan C, Redding N, Khella S, Mirza N. Laryn geal tremor: co-occurrence with other movement disorders. ORL J Otorhi nolaryngol Relat Spec 2010;72:291 – 294. 14. White L, Klein A, Hapner E, et al. Co-prevalence of tremor with spasmodic dysphonia: a case-control study. Laryngoscope 2011;121:1752 – 1755.

questionnaires that they felt that the effect of their last injection was wearing off at the time of follow-up. There fore, we believe our VHI-10 and CAPE-V scores may underestimate injection bene fi t. Our subjective scores, however, asked patients to recall their maximum bene fi t, which may provide a more accurate assessment of peak bene fi t. We also acknowledge that these measures are not ideal at the time of injection, but were another data point that could hold more meaning if studied prospectively. Though this introduces the risk of recall bias, the fact that VHI-10 and overall CAPE-V scores both show improvement alongside subjective scores — albeit to a non – statistically signi fi cant degree — suggests a consis tent and real response when comparing TA+S injections to TA alone in patients with both tremor types. Previous studies have used patient diaries to better ascertain peak bene fi t 6 ; however, CAPE-V scores must be obtained in person. Asking patients to come into clinic during peak bene fi t could incur time and cost bene fi ts, as patients would not likely be ready for their subsequent injections and this would require additional clinic visits. This was beyond the scope of this retrospective series. Additionally our study did include patients with elements of spas modic dysphonia, which is unsurprising as the two pathologies are known to be frequently comorbid. 13,14 In an effort to focus on VT, only patients with a majority pro fi le of tremor were included. To ensure the coincidence of VT and spasmodic dysphonia did not skew our data, we compared outcomes between pure tremor patients and those with a minor spasmodic dysphonia pro fi le, and found no statistically signi fi cant difference in outcomes. Further studies, such as prospective and randomized trials, could provide more insight into outcomes of strap muscle injections for patients with vertical tremor compo nents. Additionally, methodology to assess voice outcomes during peak bene fi t would be bene fi cial but may be logis tically challenging.

Laryngoscope 129: June 2019

Nelson et al.: Strap Muscle Injections for Vocal Tremor 1437