Closed-loop deep brain stimulation using chronic intracranial cortical sensing to inform subcortical stimulation delivery
- Luka Milosevic, University Health Network
Many patients with Parkinson’s disease experience freezing of gait (FoG), a debilitating symptom defined by “episodic absences or marked reduction of forward progression of the feet despite the intention to walk.” FoG can lead to reduced mobile independence and increased risk of falls, which can cause serious injury or even death. Unfortunately, FoG is often unresponsive to pharmacological therapies and deep brain stimulation (DBS). DBS involves the surgical implantation of permanent electrodes deep within the brain that are connected to an electrical pulse generator under the skin of the chest (like a cardiac pacemaker). Conventional DBS involves rapid delivery of electrical impulses, 24-hours/day, to a specific brain region implicated in the disease. Despite its efficacy for most motor symptoms of Parkinson’s disease, effective management of FoG can remain problematic. A new method of DBS delivery, termed “closed-loop” DBS, would instead continuously monitor electrical activity of the brain and only deliver stimulation upon detection of “unhealthy” activity that is indicative of symptom presence. In this study, we will make use of a new-generation device which is capable of wirelessly transmitting brain activity from inside of the skull. Our objectives are threefold. Firstly, in a controlled experimental environment with stimulation turned off, we will investigate neuro-biomarkers of FoG (i.e. readouts from the brain that indicate in real-time when the patient will experience FoG). Secondly, we will study different patterns of stimulation to learn which is best for ameliorating FoG (e.g. fast vs. slow patterns of electrical impulses). Finally, we will combine knowledge from these two objectives in an experimental application of closed-loop DBS, which will deliver the most optimal stimulation pattern upon real-time detection of FoG. This new generation brain stimulation strategy holds great promise not only for Parkinson’s disease, but may also be of use in many other neurological disorders.