Objective: To determine if individuals with cervical dystonia have altered vestibular function compared to unaffected individuals, and whether botulinum toxin treatment alters those variables.

Background: Cervical dystonia is the most common idiopathic focal dystonia, and studies have demonstrated decreased proprioceptive response to stretch of neck muscle spindles in these patients. Individuals with cervical dystonia and tremor also have impaired dynamic balance changes compared to those with tonic cervical dystonia, suggesting tremor may worsen vestibular function.

Methods: Participants with cervical dystonia with and without tremor were assessed at a baseline visit on the day of their regularly scheduled botulinum toxin injections. Assessments included Fukuda, modified Romberg, and subjective visual vertical tests, as well as the Activities-specific Balance Confidence (ABC) Scale, Cervical Dystonia Impact Profile (CDIP-58), and the pain, disability, and motor severity sections of the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS). All measures performed at the baseline visit were repeated 4 to 6 weeks after botulinum toxin injections. Controls only completed Fukuda, modified Romberg, and subjective visual vertical tests at one visit. For data analysis individuals with cervical dystonia will be divided into three groups based on severity of tremor score and degree of rotation, laterocollis, anterocollis, and retrocollis on the TWSTRS motor severity scale: Group 1: tremor score ≤1 on TWSTRS scale, Group 2: tremor ≥ 2 and total score of ≤1 for rotation, laterocollis, anterocollis, and retrocollis on the TWSTRS scale, and Group 3: tremor ≥ 2 and score ≥ 2 for rotation, laterocollis, anterocollis or retrocollis on the TWSTRS scale.

Results: The study is currently being completed and results will be presented at the meeting. To date 30 individuals have been enrolled (10 controls and 20 with cervical dystonia). Mean age of controls is 56 ± 14.7 years and individuals with cervical dystonia 65 ± 8.3 years.

Conclusions: The results of this study will determine whether individuals with cervical dystonia have altered vestibular function compared to controls, and whether factors such as tremor are associated with vestibular dysfunction. The impact of botulinum toxin injections on vestibular function in patients with cervical dystonia will also be examined.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/assessing-vestibular-function-in-individuals-with-cervical-dystonia-and-the-effects-of-botulinum-toxin-treatment/