title: Combined use of transcranial magnetic stimulation and metal electrode implants: a theoretical assessment of safety considerations.
abstract: This paper provides a theoretical assessment of the safety considerations encountered in the simultaneous use of transcranial magnetic stimulation (TMS) and neurological interventions involving implanted metallic electrodes, such as electrocorticography. Metal implants are subject to magnetic forces due to fast alternating magnetic fields produced by the TMS coil. The question of whether the mechanical movement of the implants leads to irreversible damage of brain tissue is addressed by an electromagnetic simulation which quantifies the magnitude of imposed magnetic forces. The assessment is followed by a careful mechanical analysis determining the maximum tolerable force which does not cause irreversible tissue damage. Results of this investigation provide useful information on the range of TMS stimulator output powers which can be safely used in patients having metallic implants. It is shown that conventional TMS applications can be considered safe when applied on patients with typical electrode implants as the induced stress in the brain tissue remains well below the limit of tissue damage.
authors.affiliation: Sunnybrook Research Institute and Department of Medical Biophysics, University of Toronto, Toronto, Canada. l.golestani@gmail.com
authors.forename: Laleh
authors.initials: L
authors.lastname: Golestanirad
authors.forename: Hossein
authors.initials: H
authors.lastname: Rouhani
authors.forename: Behzad
authors.initials: B
authors.lastname: Elahi
authors.forename: Kamal
authors.initials: K
authors.lastname: Shahim
authors.forename: Robert
authors.initials: R
authors.lastname: Chen
authors.forename: Juan R
authors.initials: JR
authors.lastname: Mosig
authors.forename: Claudio
authors.initials: C
authors.lastname: Pollo
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Graham
mesh_terms: D001921:Brain / Q000033:anatomy & histology / Q000166:cytology; D004553:Electric Conductivity; D004567:Electrodes, Implanted / Q000009:adverse effects*; D020342:Finite Element Analysis; D006801:Humans; D008297:Male; D008670:Metals; D008953:Models, Anatomic; D012449:Safety; D050781:Transcranial Magnetic Stimulation / Q000009:adverse effects*
chemical_list: D008670:Metals