title: A comparative study of the effects of pulse parameters for intracranial direct electrical stimulation in epilepsy.
abstract: OBJECTIVE
  Intracranial direct electrical stimulation (iDES) uses different parameters for mapping the epileptogenic and functional areas in patients with drug-resistant epilepsy. We aim at finding the common factor driving the electrographic responses to various iDES protocols reported in the literature.
  
  
  METHODS
  We recorded early responses to single-pulse iDES in 11 subjects undergoing stereoelectroencephalographic presurgical evaluation. We systematically explored the role of several pulse parameters in evoking responses: monophasic versus biphasic pulses, current intensity, and pulse duration. We performed a correlation and regression analysis between responses to different protocols by amplitude, duration, and charge per phase.
  
  
  RESULTS
  Regression analysis revealed that the responses were similar for the same charge per phase, regardless of their pulse duration and amplitude. Over eighty percent (82.8%) of the responses to variable pulse duration biphasic stimulation and between 58.6% and 81.9% of the responses to monophasic stimulation, depending on pulse polarity, were correlated to the responses evoked by the variable amplitude biphasic protocol, when expressing stimulus strength in terms of charge per phase.
  
  
  CONCLUSIONS
  Regardless of the combination of different stimulation currents, it is the underlying charge per phase parameter that determines the magnitude of the responses to single-pulse electrical stimulation.
  
  
  CONCLUSIONS
  Our results provide a unifying method for comparing iDES protocols.
authors.affiliation: Physics Department, University of Bucharest, Bucharest, Romania.
authors.forename: Cristian
authors.initials: C
authors.lastname: Donos
authors.affiliation: Neurology Department, Carol Davila University of Medicine and Pharmacy, Bucharest, Romania; Neurology Department, University Emergency Hospital, Bucharest, Romania.
authors.forename: Ioana
authors.initials: I
authors.lastname: Mîndruţă
authors.affiliation: Neurosurgery Department, Bagdasar-Arseni Hospital, Bucharest, Romania.
authors.forename: Jean
authors.initials: J
authors.lastname: Ciurea
authors.affiliation: Neurology Department, University Emergency Hospital, Bucharest, Romania.
authors.forename: Mihai Dragos
authors.initials: MD
authors.lastname: Mălîia
authors.affiliation: Physics Department, University of Bucharest, Bucharest, Romania; FHC Inc., Bowdoin, ME, USA. Electronic address: andrei.barborica@fizica.unibuc.ro.
authors.forename: Andrei
authors.initials: A
authors.lastname: Barborica
mesh_terms: D000293:Adolescent; D000328:Adult; D000069279:Drug Resistant Epilepsy / Q000503:physiopathology*; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D065908:Transcranial Direct Current Stimulation / Q000379:methods*
keywords: Drug-resistant epilepsy; Single-pulse electrical stimulation; Stereoelectroencephalography