Seizure risk with repetitive TMS: Survey results from over a half-million treatment sessions

• Published in: Brain stimulation Vol. 14; no. 4; pp. 965 - 973
• Main Authors: Taylor, Joseph J., Newberger, Noam G., Stern, Adam P., Phillips, Angela, Feifel, David, Betensky, Rebecca A., Press, Daniel Z.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.07.2021; Elsevier
• Subjects: Interventional psychiatry; Risk; Safety; Seizure; Transcranial magnetic stimulation; Risk; Seizure; Transcranial magnetic stimulation; Safety; Interventional psychiatry
• ISSN: 1935-861X; 1876-4754
• DOI: 10.1016/j.brs.2021.05.012

Seizures are rare during repetitive transcranial magnetic stimulation (rTMS) treatment, but estimating risk is difficult because of study heterogeneity and sampling limitations. Moreover, there are few studies comparing rates between device manufacturers. The objective of this study was to calculate rTMS seizure rates across various FDA-cleared devices in naturalistic clinical settings. In July and August 2018, approximately 500 members of the Clinical TMS Society (CTMSS) were electronically surveyed about seizures in their practices. Seizures were distinguished from non-seizures by a remote semi-structured interview with a Board-certified neurologist and Co-Chair of the CTMSS Standards Committee. Exact Poisson calculations were used to estimate seizure rates and confidence intervals across the four most widely used manufacturers. The survey was completed by 134 members, with 9 responses excluded because of data inconsistencies. In total, 18 seizures were reported in 586,656 sessions and 25,526 patients across all device manufacturers. The overall seizure rate was 0.31 (95% CI: 0.18, 0.48) per 10,000 sessions, and 0.71 (95% CI: 0.42, 1.11) per 1000 patients. The Brainsway H-coil seizure rate of 5.56 per 1000 patients (95% CI: 2.77,9.95) was significantly higher (p < 0.001) than the three most widely used figure- 8 coil devices’ combined seizure rate of 0.14 per 1000 patients (95% CI: 0.01, 0.51). The absolute risk of a seizure with rTMS is low, but generic Brainsway H-coil treatment appears to be associated with a higher relative risk than generic figure- 8 coil treatment. Well-designed prospective studies are warranted to further investigate this risk. •Clinical TMS Society Members were surveyed about TMS seizures in their practices.•Reported seizures were reviewed by a Board-certified neurologist.•18 seizures were reported in 586,656 sessions and 25,526 patients across devices.•Overall seizure rate was 0.31 per 10,000 sessions and 0.71 per 1000 patients.•H-coil seizure rate was significantly higher than figure- 8 coil seizure rate.