Objective: To investigate pallidal and cortical activity associated with motor signs in Parkinson’s disease (PD), by wireless transmission from an implantable bidirectional interface at home over long periods.

Background: Deep brain stimulation (DBS) of the globus pallidus (GP) is an effective treatment for the motor signs of PD, and may be preferred over alternative targets in patients with depression or mild cognitive impairment. Pallidal electrical activity and pallidocortical interactions have been studied intraoperatively or for brief periods in-hospital with externalized leads, but physiology of the pallidum and its cortical interactions have not been studied over long periods in naturalistic environments.

Method: A PD patient with motor fluctuations, tremor and dyskinesias underwent staged bilateral implantation of pallidal and motor cortical quadripolar leads attached to an investigational neural interface capable of both recording and stimulation (Summit® RC+S, Medtronic). Cortical and subcortical signals were recorded simultaneously and chronically while the patient experienced periods of tremor, rigidity and/or dyskinesia. Signals were recorded in a bipolar configuration, sampled at up to 1000 Hz and streamed wirelessly to an external computer. Behavioral state was tracked with a wristwatch-style monitor (Parkinson’s Kinetograph, Global Kinetics Inc.).

Results: Over 1000 hours of data were recorded. GP oscillatory activity at 13 Hz and 25Hz was associated with tremor and rigidity, respectively, while a 7Hz spectral peak in primary sensory cortex emerged during tremor. Dopaminergic medication resulted in a reduction of these oscillations and the emergence of a 75 Hz gamma oscillation in primary motor area. Therapeutic pallidal stimulation reduced the off-state biomarkers, and enhanced the cortical “prokinetic” gamma oscillation while also entraining it at half the stimulation frequency.

Conclusion: Field potentials in pallidum, motor cortex, and sensory cortex offer distinct physiological signatures of specific motor signs. These signals could be used in an adaptive DBS paradigm in order to reduce side effects and improve efficacy.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/chronic-wireless-streaming-of-pallidal-and-cortical-recordings-in-parkinsons-disease-over-1000-hours-at-home/