Mechanisms and efficacy of deep brain stimulation in epilepsy

Abstract

This chapter discusses the mechanism and efficacy of deep brain stimulation (DBS) in epilepsy. There is evidence suggesting that several subcortical neuronal circuits including the nigral control of epilepsy system (NCES), the reticular activating system (RAS), and the circuit of papez modulate cortical excitability. These circuits contain subcortical stimulation sites as relais-stations and explain in part the mechanisms, by which cortical excitability is modulated via DBS. In DBS for seizure control, the following three factors correlate closely with each other and are briefly discussed: (1) stimulation parameters, (2) timing of the stimulus, (3) localization of the stimulus. Six stimulation paradigms are used to treat epilepsy in vivo models. The four local stimulation paradigms applied at the epileptogenic zone include closed-loop high-frequency pulsatile stimulation, closed-loop direct current (DC) stimulation, open-loop lowfrequency pulsatile stimulation, and open-loop DC stimulation. Remote stimulation has been used as closed-loop high-frequency stimulation and open-loop high-frequency stimulation. Deep brain stimulation is a promising alternative technique in the prevention and treatment of medically refractory epilepsy in patients that do not qualify for epilepsy surgery. Parameters for the selection of the ideal target and ideal stimulation paradigm in each case have to be defined and may vary from case to case.