Wearable Sensor for Responsive DBS for ET

The purpose of this study is evaluate the effectiveness and safety of a possible new treatment for Essential Tremor (ET) using external wearable sensors, which have the capability of recording acceleration and Electromyography (EMG). This therapy is called Responsive Deep Brain Stimulation (R-DBS). R-DBS systems will communicate with a computer, and apply stimulation when the computer detects patterns associated with tremor. This detection will suppress pathological activity and improve or alleviate the tremor.

Currently, DBS is approved for the treatment of ET; however, stimulation is delivered continuously even when tremor or other symptoms are absent. Continuous DBS can lead to unwanted side effects such as stuttering and gait\\balance problems. On the other hand, R-DBS will turn on only if activity associated with ET from the external sensors is detected.

The overall purpose of this application is to capture pathological activity related to essential tremor using external wearable sensors to responsively initiate or terminate DBS. To this end, the researchers propose to use the Nexus-D system, which requires a firm ware update to an Activa Implantable Neurostimulator (INS), and it will in a smart way turn DBS on/off in patients. The study team will recruit subjects with Activa SC or PC neurostimulator implants during 6 post-operative programming visits. The research group is already familiar with and is in possession of the Nexus-D system, and the investigators have successfully performed responsive DBS in two patients with Tourette syndrome (TS) and in four patients with Parkinson's disease in acute settings. The lab is also equipped with wireless wearable sensor and amplifier systems, such as a 16-unit wireless EMG+ acceleration+inertia Trigno Wireless Bio Acquisition System (Delsys Inc, Natick, MA). The study team aims to combine these signal modalities to capture pathological symptoms and generate commands to initiate or terminate DBS (also record adverse side effects, if any). The project goal is to characterize the clinical efficacy, side effect profile, and battery life of closed-loop DBS in acute settings using wearable sensors in essential tremor patients.

Eligibility Criteria:
Inclusion Criteria:

* Provide informed consent
* Patient is over 21 years of age
* Patient has had a significant disabling, medication-refractory upper extremity tremor with no evidence of non-ET central nervous system disease or injury for at least three (3) months prior to implantation of Activa SC, PC, or RC device.
* Patient receives Vim electrode and Activa SC, PC or RC device implants, and recovers fully after surgery.
* Patient is available for study participation after their clinical programming appointments for six months.

Exclusion Criteria:

* Medication related movement disorders.
* Any suspicion of Parkinsonian tremor, including presence of Parkinsonian features such as bradykinesia, rigidity, or postural instability.
* Severe medical co-morbidity including cardiovascular disorder, lung disorder, kidney disease, continuous neurological disease, hematological disease, or frailty that impact tolerability of the surgery as judged by the screening physicians.
* Patient is undergoing a lead revision surgery.