Objective: To delineate correlates of altered sensory processing in laryngeal dystonia (LD) in both presence and absence of somatosensory input and their modulation by botulinum toxin.

Background: Abnormal sensory processing is implicated in dystonia pathophysiology, but has within the larynx area yet only been seen in the vocalization task setting[1]. Further, assessment of its role in relation to auditory sensory processing, an important component in the phonation loop, cannot easily be modelled during task. While botulinum toxin improves symptoms, its effect on the sensory systems in LD has not yet been delineated.

Method: 14/15 adductor-type LD patients/healthy controls where compared undergoing tactile-stimulation of face and hand areas and hypothesis-driven evaluations of sensorimotor/auditory resting-state long- and short-range connectivity using independent component and regional homogeneity analysis. Patients were investigated before and additionally 4-6 weeks after botulinum toxin treatment.

Results: LD patients showed increased primary and higher-order somatosensory cortex activity involving both face and hand representations during tactile stimulation. Long-range resting state functional-connectivity was altered in the supplementary/premotor cortex in the sensorimotor network and auditory cortex in the auditory network. Altered short-range functional connectivity was seen in the temporo-parietal junction. While the spatial pattern of connectivity/activity changes persisted as trend after botulinum toxin injection in sensorimotor cortices, this was not the case for primary auditory cortex connectivity changes.

Conclusion: Task-related abnormal sensory processing in the disease affects both somatosensory and auditory domains. The pattern of functional connectivity changes hints at an altered integration of somatosensory with auditory information. While botulinum toxin relieves symptoms, it does not seem to modulate the underlying cortical sensorimotor system dysfunction in the disease.

References: [1] Simonyan K., Ludlow CL. Abnormal Activation of the Primary Somatosensory Cortex in Spasmodic Dysphonia: An fMRI Study, Cerebral Cortex, Volume 20, Issue 11, 1 November 2010, Pages 2749–2759

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MDS Abstracts - https://www.mdsabstracts.org/abstract/altered-sensory-processing-in-somatosensory-and-auditory-domains-in-laryngeal-dystonia/