Inertial-based control system concepts for the treatment of movement disorders

Abstract

This work provides a summary of the state-of-the-art in inertial-based adaptive stimulation strategies for treatment of movement disorders like Parkinson’s disease and Essential Tremor. A review of recent technical and clinical neuroscience is provided to give a state-of-the-art overview. We then propose a closed-loop system concept using an accelerometer and a phase locked loop algorithm as a conceptual methodology for enhanced therapy systems. The remaining challenges to practical implementation are then briefly described.

Stimulating at the right time: phase-specific deep brain stimulation

“…To implement phase-specific stimulation, tremor phase was estimated from the tremor frequency and the timing of the preceding zero crossing. When a certain tremor phase was detected, a TTL pulse was sent to either an externalized stimulator (for the externalized patients) (Little et al , 2013) or to the Nexus-D (for the chronically implanted patients) (Cagnan et al , 2015 a ), which in turn delivered a burst of high frequency stimulation unilaterally for 35 ms (i.e. four to six pulses, Supplementary Fig.…”

“…Critically, we implement phase interference of tremor with DBS in a clinically tractable paradigm that derives stimulation timing from peripheral inertial sensors attached to patients’ tremulous limbs rather than sensing oscillations from the brain directly, using existing neurostimulator technology (Fig. 1) (Cagnan et al , 2015 a ).

Figure 1 Phase-specific stimulation.

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Deep brain stimulation: a review of the open neural engineering challenges

“…Neurophysiological-recordings-based biomarkers have not been the only type of feedback inputs tested for aDBS. Other kind of signals were proposed for this scope: kinematic [249,250], EMG [251], biochemical potential [252] and eHealth and mHealth monitoring [253,254].…”

Emerging technologies for improved deep brain stimulation

“…Various classes of signals have been used to determine when and how much to stimulate, including pathological neural activity 79,82,88–90 and peripheral measurements 91,92 . Biomarkers need not necessarily be directly related to disease mechanisms, but should correlate with the severity of disease symptoms 36,93–95 and track the response to therapeutic interventions 39,46,93,95,96 .…”

“…A different approach is the use of peripheral sensors for feedback, which also circumvents stimulus artifact and may prove useful for gait disturbance and tremor 91,92,99–102 . However, with this approach additional constraints need to be addressed, such as the energy expenditure associated with wireless communication between the peripheral sensor and the implanted stimulator, the security of wireless communication and the fact that information from peripheral sensors follows the development of symptoms and is therefore not predictive.…”