Cortical Brain Computer Interface for Closed-Loop Deep Brain Stimulation
  Essential Tremor is the most common neurological movement disorder. This progressive disease causes uncontrollable rhythmic motions -most often affecting the patient's dominant upper extremity- that occur during volitional movement and make it difficult for the patient to perform everyday tasks. Medication may also become ineffective as the disorder progresses. For many patients, deep brain stimulation (DBS) of the thalamus is an effective means of treating this condition when medication fails. In current use, however, clinicians set the patient's stimulator to apply stimulation at all times- whether it is needed or not. This practice leads to excess power use, and more rapid depletion of batteries that require surgical replacement. In the work described here, for the first time, neural sensing of movement (using chronically-implanted cortical electrodes) is used to enable or disable stimulation for tremor. Therapeutic stimulation is delivered only when the patient is actively using their effected limb, thereby reducing the total stimulation applied, and potentially extending the lifetime of surgically-implanted batteries. This work, which involves both implanted and external subsystems, paves the way for the future fully-implanted closed-loop deep brain stimulators. 
Jeffrey A. Herron, Margaret C. Thompson, Timothy Brown, Howard J.   Chizeck, Jeffrey G. Ojemann, and Andrew L. Ko
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