Impaired consciousness during seizures has a major negative impact on quality of life for people with epilepsy. Consequences include risk of motor vehicle accidents, drowning, poor work and school performance, and social stigmatization. Impaired ictal/postictal arousal may also compromise breathing leading to sudden unexpected death in epilepsy. Although the primary goal of epilepsy care is to stop seizures, restoring conscious awareness in patients whose seizures cannot be stopped (by medications, surgery or deep brain stimulation) could significantly improve outcome. Disorders of consciousness other than epilepsy have long been known to arise from dysfunction of subcortical-cortical arousal circuits. Deep brain stimulation (DBS) of the thalamic intralaminar central lateral nuclei (CL) is a promising approach to restore conscious arousal currently being trialed for chronic disorders of consciousness (N. Schiff, NINDS UH3 NS095554). Recent neuroimaging and EEG studies have shown that transient impaired consciousness in temporal lobe epilepsy (TLE) seizures also depends on subcortical-cortical arousal including thalamic CL. Translational studies from our research group further demonstrate depressed CL function in limbic seizures, and most importantly that thalamic CL stimulation has the potential to restore physiological and behavioral arousal in the ictal and postictal periods. DBS treatment of epilepsy has advanced rapidly with FDA approval of responsive neurostimulation (RNS, NeuroPace) and thalamic anterior nucleus stimulation (Medtronic). Investigational devices such as the RC+S (Medtronic) provide a unique opportunity for responsive stimulation of up to 4 separate brain regions, enabling conventional sites such as hippocampus (HC) to be combined with innovative targets such as thalamic CL. Meanwhile, Dr. Worrell?s group at Mayo has developed the Epilepsy Personal Assistant Device (EPAD), a custom application running on a hand-held device with bi-directional communication with the RC+S. The EPAD will enable cloud-based data storage, seizure diaries, and automatic behavioral tests similar to those we have validated previously. Therefore, our goal is to develop and pilot test the feasibility and safety of bilateral thalamic CL stimulation using RC+S to restore conscious arousal in TLE seizures which are not stopped by conventional responsive neurostimulation, offering hope to greatly improve quality of life in these patients.
Our aims are to first conduct final benchtop preclinical verification of RC+S and EPAD algorithms for CL stimulation leading to FDA IDE approval. Second, we will initiate a small clinical trial implanting RC+S in patients with refractory TLE and beginning with open-label HC stimulation and baseline EPAD behavioral testing. Third, we will adjust responsive thalamic CL stimulation parameters for arousal. Finally, we will test safety and initial feasibility of responsive CL stimulation to restore arousal during seizures.
Temporal lobe seizures with impaired conscious awareness greatly impair quality of life and sometimes cannot be stopped by medications, surgery or responsive neurostimulation. We plan to stimulate arousal areas of the thalamus in these patients to restore consciousness during and following seizures.