Objective: To investigate brain activity in laryngeal dystonia (LD) patients compared to healthy controls during asymptomatic motor tasks of sequential and learned finger-tapping, as well as LD phenotype- and genotype-specific differences in brain activity for each tapping task.

Background: LD is an isolated focal dystonia characterized by involuntary spasms in the laryngeal muscles during speech production. The phenomenology of LD has been well documented during symptomatic and asymptomatic speech tasks, but less is known about the affected neural mechanisms during asymptomatic motor tasks involving unaffected body regions.

Method: We performed functional magnetic resonance imaging using a block design to study brain activity during a right-handed sequential finger-tapping task and a left-handed learned finger-tapping task in LD patients and controls. During sequential tapping, participants tapped continuously for 30 seconds with their right hand. During learned tapping, participants tapped continuously for 30 seconds with their left hand, repeating the learned sequence of 5-4-2-3-1 fingers. Group-level comparisons between LD patients and controls, abductor vs. adductor LD, and sporadic vs. familial LD were performed using voxel-wise ANOVA. Statistical significance was set at family-wise error corrected p ≤ 0.05.

Results: During sequential finger-tapping, LD patients showed increased activity in the left precuneus compared to healthy controls. Patients with abductor LD had increased activity in the left inferior parietal and middle temporal cortices compared to patients with adductor LD. During learned finger-tapping, brain activity was increased in the right cerebellum in LD patients compared to controls but there were no differences between abductor and adductor LD patients. There were no differences between sporadic and familial LD patients on any task.

Conclusion: Altered brain activity during asymptomatic finger tapping in LD patients might be related to previously found abnormal striatal dopamine release during the execution of a similar task. Abnormal brain activity is phenotype- but not genotype-specific, pointing to likely a compensatory feature of these alterations.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/neural-signatures-of-laryngeal-dystonia-during-asymptomatic-tasks-of-sequential-and-learned-finger-tapping/