Optimizing Botox regimens in patients with adductor spasmodic dysphonia and essential tremor of voice: A 31‐year experience

Abstract

Objective The purpose of this study was to quantitatively compare the effectiveness of unilateral and bilateral botulinum toxin A (BTX‐A) injections for mitigating undesirable weak/breathy voice quality and dysphagia for patients with adductor spasmodic dysphonia and/or essential tremor of voice (ETV). Methods Data were collected from the medical records of 319 patients, yielding three treatment cohorts: patients who received an equal dose bilateral injection regimen (BL=) throughout their course of treatment at VUMC, patients who switched to a unilateral injection regimen (UL), and patients who switched to an unequal dose bilateral injection regimen (BL≠). Changes in length of improvement, duration of weak/breathy voice, and dysphagia severity were compared. Results The BL = treatment group reported the longest duration of improved voice. Shorter periods of improved voice were reported at baseline by patients who later switched to UL or BL ≠ injection regimens. Patients receiving UL injections reported significantly reduced weak/breathy voice and dysphagia. Patients receiving BL ≠ injections reported increased length of improved voice; however, dysphagia symptoms increased. Ninety‐two percent of patients with ETV switched to a UL regimen, with 61% of patients transitioning within the first three injections. Conclusions Patients with pronounced dysphagia and extended periods of weak/breathy voice may benefit from a UL injection approach to mitigate side effects from BTX‐A without sacrificing improved voice outcomes. For patients seeking to extend their length of improved voice, a BL ≠ injection regimen may be effective provided the adverse side effects from BTX‐A are minimal. Patients with ETV may benefit from a UL injection approach at the outset of their course of treatment with BTX‐A. Level of evidence III.

Comparison of the efficacy and adverse effects of unilateral or bilateral botulinum toxin injections for adductor spasmodic dysphonia: a systematic review and meta-analysis

“…Our study has some limitations. First, the included studies contained patients with both ADSD and comorbid essential vocal tremor [ 18 ]. ADSD and essential tremor both manifest as impaired neuromuscular control of the larynx.…”

“…Finally, there was a general lack of subgroup analysis in the injection approach, which is problematic as the unilateral/bilateral dichotomy is overly simplistic. Some studies used alternating unilateral injections [ 12 , 18 , 19 ] versus consistent unilateral injections, warranting comparison. Other variations, including dose equality for bilateral injections [ 18 ], should also be considered for future subgroup analyses using more granular groupings.…”

“…Some studies used alternating unilateral injections [ 12 , 18 , 19 ] versus consistent unilateral injections, warranting comparison. Other variations, including dose equality for bilateral injections [ 18 ], should also be considered for future subgroup analyses using more granular groupings.…”

“…The length of time that patients experienced a breathy voice quality was reported in four retrospective cohort studies [ 12 , 18 – 20 ], one prospective cohort study [ 22 ], and one non-randomized controlled study [ 15 ].The mixed duration of breathy voice demonstrated significant difference, but showed significant heterogeneity ( I 2 = 59%, P = 0.03), which was completely reduced by excluding the study by Upile et al from the analysis [ 22 ] ( I 2 = 35%, P = 0.19), and the result remained that unilateral injections resulted in a significantly shorter duration of breathy voice compared with bilateral injections (SMD = − 0.51, 95% CI − 0.79 to − 0.22, P = 0.0005; Fig. 4 ) [ 12 , 15 , 18 – 20 ].

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Use of Botulinum Toxin in Spasmodic Dysphonia: A Review of Recent Studies

“…Recent studies also demonstrate that non-pharmacological factors such as education before the procedure, body position, pain, and stress sensation before btx may play a role in the effect of btx on AdSD patients [ 20 ]. In addition, a study compared unilateral and bilateral btx injections quantitatively and concluded that unilateral btx is useful for patients with an extended period with weak/breathy voice quality and those with dysphagia [ 21 ].…”