Closed-loop System Using Transcranial Direct Current Stimulation (tDCS) for Epilepsy

Development of a Closed-loop Detect-and-treat System Using Transcranial Direct Current Stimulation (tDCS) for Epilepsy

In this pilot study, the researchers investigated the feasibility of a closed-loop electroencephalography (EEG) / transcranial direct current stimulation (tDCS) system for treatment of epilepsy. They looked to see the feasibility of triggering tDCS stimulation within 10 seconds of a detected EEG partial-onset seizure, and also a proof-of-principle determination of whether tDCS applied during this vulnerable period may be feasible to prevent the oncoming seizure.

This study required 5 visits over the course of approximately 8 weeks. Each visit was separated by at least 2 weeks. Two of the visits had 24-hour EEG monitoring sessions. During these two sessions, the EEG and tDCS were hooked into a closed loop system, such that when seizure activity wasdetected, the tDCS was triggered to deliver stimulation. Subjects received active stimulation or sham stimulation sessions during the first 24-hour visit, and the opposite during the second. The subjects were randomized and counterbalanced.

We have also added a healthy subjects cohort to assess the feasibility of the closed loop system. In order to test the proof-of-concept of this system, the experiment will focus on detecting and acting upon alpha- and beta-band changes traced in the EEG activity that is being recorded, and provide tDCS stimulation based upon those changes. We will enroll 6 subjects who will have 2 visits each. During these two visits subjects will be randomized to active or sham stimulation sessions and receive the opposite during their second visit.

Inclusion Criteria (Epileptics)

• Disabling motor simple partial seizures, complex partial seizures, and/or secondarily generalized seizures. Disabling refers to seizures that are severe enough to significantly impair functional abilities in areas such as employment, psychological or social wellbeing, education or mobility.
• Failed treatment with a minimum of two antiepileptic medications.
• Experienced an average of three or more disabling simple weekly partial seizures, complex partial seizures and/or secondarily generalized seizures.
• Between the ages of 18 and 70 years.
• No more than two epileptogenic regions in the brain.
• Must be able to provide informed consent themselves.

Exclusion Criteria

• Has a progressive neurological or systemic disease.

• Has a history of nonepileptic seizures.

• Has an implanted metallic device, aneurysm clips, cochlear implants, or spinal cord stimulator.

• Has suffered a severe traumatic brain injury with skull fracture.

• Contraindications to tDCS

  • metal in the head
  • implanted brain medical devices

• Pregnancy

• Any implanted electrical medical device, including pacers and implanted cardiac defibrillators

Inclusion criteria (Healthy Subjects)

- Healthy subjects age 18 and older

Exclusion criteria:

• Existence of major neurologic or psychiatric condition (i.e. epilepsy, severe depression)

• History of head injury resulting in more than a momentary loss of consciousness

• Previous neurosurgery

• A history of significant alcohol or drug abuse in the prior 6 months

• Presence of unstable medical conditions, such as; uncontrolled diabetes mellitus, cardiac pathology, cancer, kidney insufficiency, acute thrombosis

• Contraindication to tDCS

  • metal in the head
  • implanted electronic medical devices

• Pregnancy