title: tDCS-induced analgesia and electrical fields in pain-related neural networks in chronic migraine.
abstract: OBJECTIVE
  We investigated in a sham-controlled trial the analgesic effects of a 4-week treatment of transcranial direct current stimulation (tDCS) over the primary motor cortex in chronic migraine. In addition, using a high-resolution tDCS computational model, we analyzed the current flow (electric field) through brain regions associated with pain perception and modulation.
  
  
  METHODS
  Thirteen patients with chronic migraine were randomized to receive 10 sessions of active or sham tDCS for 20 minutes with 2 mA over 4 weeks. Data were collected during baseline, treatment and follow-up. For the tDCS computational analysis, we adapted a high-resolution individualized model incorporating accurate segmentation of cortical and subcortical structures of interest.
  
  
  RESULTS
  There was a significant interaction term (time vs group) for the main outcome (pain intensity) and for the length of migraine episodes (ANOVA, P < .05 for both analyses). Post-hoc analysis showed a significant improvement in the follow-up period for the active tDCS group only. Our computational modeling studies predicted electric current flow in multiple cortical and subcortical regions associated with migraine pathophysiology. Significant electric fields were generated, not only in targeted cortical regions but also in the insula, cingulate cortex, thalamus, and brainstem regions.
  
  
  CONCLUSIONS
  Our findings give preliminary evidence that patients with chronic migraine have a positive, but delayed, response to anodal tDCS of the primary motor cortex. These effects may be related to electrical currents induced in pain-related cortical and subcortical regions.
authors.affiliation: Headache & Orofacial Pain Effort, Department of Biologic and Materials Sciences, School of Dentistry, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Alexandre F
authors.initials: AF
authors.lastname: Dasilva
authors.forename: Mariana E
authors.initials: ME
authors.lastname: Mendonca
authors.forename: Soroush
authors.initials: S
authors.lastname: Zaghi
authors.forename: Mariana
authors.initials: M
authors.lastname: Lopes
authors.forename: Marcos Fabio
authors.initials: MF
authors.lastname: Dossantos
authors.forename: Egilius L
authors.initials: EL
authors.lastname: Spierings
authors.forename: Zahid
authors.initials: Z
authors.lastname: Bajwa
authors.forename: Abhishek
authors.initials: A
authors.lastname: Datta
authors.forename: Marom
authors.initials: M
authors.lastname: Bikson
authors.forename: Felipe
authors.initials: F
authors.lastname: Fregni
mesh_terms: D000293:Adolescent; D000328:Adult; D000698:Analgesia / Q000379:methods*; D004599:Electric Stimulation Therapy / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008881:Migraine Disorders / Q000503:physiopathology / Q000628:therapy*; D009044:Motor Cortex / Q000503:physiopathology*; D009415:Nerve Net / Q000503:physiopathology*; D010146:Pain / Q000503:physiopathology; D059408:Pain Management; D010147:Pain Measurement; D058748:Pain Perception / Q000502:physiology; D016037:Single-Blind Method; D016896:Treatment Outcome