The goals of this project are 1) to determine the incidence of neurological voice disorders in patients with dystonia and essential tremor undergoing deep brain stimulation (DBS), 2) investigate the neuroimaging and intracranial neurophysiology correlates of voice dysfunction in these subjects, and subsequently 3) determine the effects of DBS on voice function.

Loss of voice control, which is critical for conveying effective spoken communication, is often a significant feature in patients with movement disorders, such as dystonia and essential tremor. Voice dysfunction, however, has been overshadowed clinically by a focus on limb motor symptoms. For example, deep brain stimulation (DBS) effectively reduces limb dystonia and tremor in these patients, but the modulation of voice symptoms by DBS has been vastly understudied. It is assumed that the production and modulation of voice are regulated by the basal ganglia-thalamo-cortical network in a loop architecture that is common to all motor behaviors. There is, however, little empirical data to inform our specific understanding of how voice function is encoded in basal ganglia-thalamo-cortical interactions. The overall goal of this research is to use a combination of invasive and non-invasive human neuroscience to improve our understanding of the incidence and neural correlates of neurological voice disorders (laryngeal dystonia and voice tremor) in patients with isolated dystonia and essential tremor undergoing DBS surgery. The investigators will use simultaneous electrocorticography (ECoG) and subcortical activity recording in dystonia and tremor patients who are awake and speaking during DBS implantation surgery. The results of this research will inform the development of strategies for closed-loop brain stimulation specifically to treat neurological voice dysfunction that can be tested in a subsequent clinical trial.

Inclusion

1. Clinical indications to proceed with DBS implantation, as determined by the clinical multidisciplinary movement disorders board, including: a) definitive diagnosis of essential tremor or dystonia, b) medically refractory disease, c) adequate performance on neuropsychological evaluation as determined by a licensed clinical neuropsychologist.
2. The ability to comply with test directions, complete pre-operative task training, and provide informed consent.
3. Age 18-80 years.

Exclusion

1. Inability to understand or perform the task outlined in the protocol during a pre-surgery training session. 2. Significant hearing loss.

3. Cortical venous anatomy that could potentially obstruct ECoG electrode placement, as determined by the surgeon, visualized on pre-op MRI or during surgery.