rTMS in Spasmodic Dysphonia

Focal dystonia is a neurological movement disorder characterized by excessive involuntary muscle contractions of any body part. Spasmodic dysphonia (SD) is a type of focal dystonia characterized by excessive contraction of intrinsic muscles in the larynx, leading to difficulty in speaking and affecting effective communication. The cause of SD is unknown and there are no treatments that produce long-term benefits. Previous studies have suggested that SD and other focal dystonias are associated with decreased inhibition in sensorimotor areas in the brain. However, no studies have investigated the effects of modulating excitability of the laryngeal motor cortex in healthy individuals or SD. The goal of this pilot project is to determine if brain excitability of the laryngeal motor cortex can be changed with low-frequency inhibitory repetitive transcranial magnetic stimulation (rTMS) in individuals with SD and healthy controls. Considering that rTMS at low frequencies (≤1 Hz) produces lasting inhibition in the brain, and that SD is associated with decreased cortical inhibition, the purpose of this pilot study is to determine safety, feasibility and response to 1Hz rTMS to the laryngeal motor cortex in individuals with SD and healthy people. The results will help understand changes associated with the disorder, as well as contribute to the development of future clinical interventions for SD.