Teager energy assessment of tremor severity in clinical application of wearable inertial sensors

Essential tremor is the most common form of involuntary movement disorder and is often a debilitating condition for those affected. In the most severe cases, long-term suppression is achieved by chronic thalamic stimulation. This stimulation is defined with numerous parameters, and determining the optimal patient-specific settings requires accurate and precise assessment of tremor severity during programming. We introduce a technique to provide such assessment of essential tremor severity by applying the Teager energy function to data collected with TEMPO 1.0, a custom, wearable, inertial sensing technology for continuous, non-invasive, objective measurement of movement disorder such as tremor. This approach affords an opportunity to analyze tremor at a finer level of granularity than is currently possible with the clinical rating scale. Additionally, our technology facilitates further research of general tremor presentation, treatment, and etiology. Results obtained from a post-operative pilot study of deep brain stimulation efficacy at the University of Virginia's Department of Neurosurgery not only quantify tremor severity for programming enhancement, but also reveal axial tremor and ipsilateral benefit -both elusive tremor observations. This paper presents our approach and preliminary findings obtained from the clinical application of TEMPO 1.0.