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.