1 Spasmodic dysphonia (SD) is a rare voice disorder characterized by involuntary movement of 2 laryngeal muscles that leads to voice breaks and a strained or strangled voice quality that 3 impairs speech. Current therapeutic options are limited. SD does not respond to current forms 4 of behavioral speech therapy. It is treated primarily with Botulinum toxin injections (Botox) to 5 provide temporary symptom relief. There is no cure for SD. 6 While SD motor symptoms are restricted to the laryngeal musculature, recent work from our 7 group (NIH 1R21DC011841) confirmed upper limb proprioceptive deficits in SD demonstrating 8 that an underlying generalized somatosensory deficit is also a feature of SD. This finding opens 9 an avenue for a missing behavioral treatment for SD. Specifically, we suggest that vibro-tactile 10 stimulation (VTS) of the larynx (voice box) is suitable tool, given that it is known to alter afferent 11 signals from the vibrated mechanoreceptors in muscles and skin. Our approach seeks to show 12 that VTS represents a non-invasive form of neuromodulation that induces measurable 13 improvements in the speech of SD patients.
Specific aims : We will demonstrate that VTS 14 induces acute, short term positive effects on voice production in SD (aim 1), and that repeated 15 application of VTS over a period of 6 weeks produces long lasting improvements in SD voice 16 quality that are retained for up to 3 months (aim2).
Aim 3 will elucidate the neurophysiological 17 mechanism behind the effectiveness of VTS by demonstrating that a) SD is associated with 18 abnormally increased levels of neuronal synchronization in the sensorimotor cortex, and b) that 19 VTS can reduce sensorimotor cortical excitation in SD by desynchronizing motor cortical neuron 20 activity. 21 Significance: This is the first systematic study on the effect of VTS on SD voice symptoms. The 22 proposal aligns with PA-14-236 (Advancing Research in Voice Disorders). If successful, the 23 proposed work would lay the scientific foundation for a clinical trial to establish the efficacy of 24 VTS therapy. Innovation: The proposal?s innovation concerns the application of new wearable 25 vibrator technology that allows for the in-home and clinical application of VTS. It will promote 26 the development of new wearable, user-programmable medical devices that could apply VTS 27 while monitoring its effect on voice production in real-time. Impact: Ultimately, VTS could 28 enlarge the limited, available therapeutic arsenal for treating voice symptoms in SD.
1 Spasmodic dysphonia (SD) is a rare, uncurable voice disorder that severely handicaps verbal communication. 2 SD is not responsive to speech therapy and symptom relief is mainly possible through Botulinum toxin 3 injection. This proposal examines the effectiveness of laryngeal vibro-tactile stimulation as a new behavioral 4 treatment for SD, which would enlarge the available therapeutic arsenal.