Physiology, Imaging and Modeling of Essential Tremor

The study team will use computer simulation and virtual reconstruction of the brain from pre-operative MRI data to calculate the fiber activation threshold for the duration that each subject is on the home settings versus the biphasic settings. The investigators will assess the feasibility of the patterns to address the worsening of ET that may occur in 20% or more of the ET population. No fiber activation threshold data was collected for the DBS OFF state since the system was not active.

The investigators will compare the degree of tremor suppression from the home settings versus active biphasic DBS. The degree of tremor will be quantified by the Fahn-Tolosa-Marin Tremor Rating Scale (sum of motor score parts A and B; range 0 - 116). A higher Tremor Rating Scale score is associated with more severe motor symptoms.

The clinical metrics represent the change from DBS OFF to the active arm (either home settings or biphasic VIN) after 4 hours of stimulation

Essential tremor motor physiology will be recorded by the Kinesia ONE accelerometer system. The Kinesia ONE system utilizes a wireless, wearable motion sensor and portable transducer to translate movement metrics into a tremor severity score ranging from 0 (no symptoms) to 4 (severe symptoms). In this study, the reported tremor severity score represents motor function captured after 4 hours of active DBS - under either the participants' home settings or the VIN biphasic configuration.

Essential tremor's effect on gait will be assessed by the GAITRite system. Patients will walk along a GAITRite floor mat to have the various gait parameters such as step length measured. The GAITRite system translates movement metrics into an objective kinematic score. In this study, the reported kinematic scores represent motor function captured after 4 hours of active DBS - under either the participants' home settings or the VIN biphasic configuration.

Essential tremor's effect on gait will be assessed by the GAITRite system. Patients will walk along a GAITRite floor mat to have the various gait parameters such as stride length measured. The GAITRite system translates movement metrics into an objective kinematic score. In this study, the reported kinematic scores represent motor function captured after 4 hours of active DBS - under either the participants' home settings or the VIN biphasic configuration.

Essential tremor's effect on gait will be assessed by the GAITRite system. Patients will walk along a GAITRite floor mat to have the various gait parameters such as step time measured. The GAITRite system translates movement metrics into an objective kinematic score. In this study, the reported kinematic scores represent motor function captured after 4 hours of active DBS - under either the participants' home settings or the VIN biphasic configuration.

Essential tremor's effect on gait will be assessed by the GAITRite system. Patients will walk along a GAITRite floor mat to have the various gait parameters such as gait cycle time measured. The GAITRite system translates movement metrics into an objective kinematic score. In this study, the reported kinematic scores represent motor function captured after 4 hours of active DBS - under either the participants' home settings or the VIN biphasic configuration.