Feasibility of TMS in patients with new generation cochlear implants

Clin Neurophysiol. 2021 Mar;132(3):723-729. doi: 10.1016/j.clinph.2020.12.013. Epub 2021 Jan 5.

Abstract

Objective: The presence of a cochlear implant is being considered an absolute contraindication for experiments and/or treatments. We aimed to verify TMS (Transcranial Magnetic Stimulation) compatibility of a new generation of cochlear implants.

Methods: In a series of experiments, we test if MED-EL cochlear implants -compatible with stable fields of magnetic resonance imaging scanning- are fully resistant even to rapidly varying magnetic fields as those generated by single pulses and low and high-frequency trains of repetitive TMS (rTMS) applied with a figure of eight coil and different magnetic stimulators.

Results: With a TMS intensity equal or below 2.2 Tesla (T) the cochlear implant and all its electronic components remain fully functional, even when the combination of frequency, intensity and number of pulses exceeds the currently available safety guidelines. Induced forces on the implant are negligible. With higher magnetic fields (i.e., 3.2 T), one device was corrupted.

Conclusions: Results exclude the risk of electronic damaging, demagnetizing or displacements of the studied cochlear implants when exposed to magnetic fields of up to 2.2 T delivered through a focal coil.

Significance: They open the way to use focal rTMS protocols with the aim of promoting neural plasticity in auditory networks, possibly helping the post-implant recovery of speech perception performance.

Keywords: Cochlear implant; Safety; TMS; Transcranial Magnetic Stimulation; rTMS.

MeSH terms

  • Cochlear Implantation / instrumentation*
  • Cochlear Implantation / standards
  • Cochlear Implantation / trends*
  • Cochlear Implants / trends*
  • Equipment Design / methods
  • Equipment Design / standards
  • Equipment Design / trends*
  • Feasibility Studies
  • Hearing Loss / diagnosis
  • Hearing Loss / physiopathology
  • Hearing Loss / surgery
  • Humans
  • Neuronal Plasticity / physiology
  • Transcranial Magnetic Stimulation / methods
  • Transcranial Magnetic Stimulation / trends*