Comparing Plasticity Effects of iTBS and 10-Hz rTMS with NMDA and GABA Receptor Modulation

Background: Visual Snow Syndrome (VSS) is characterized by visual perception of continuous static across the visual field, excessive perception of floaters, other entoptic phenomenon and non-vision related symptoms.Increased metabolism in the lingual gyrus suggests VSS may be a cortical hyperexcitability syndrome.Here we report adverse events (AE's) and tolerability for an open-label pilot treatment trial of VSS with repetitive transcranial magnetic stimulation (rTMS) to bilateral lingual gyrus (bLG).Methods: Twelve individuals with VSS underwent 1hz rTMS consisting of 1800 pulses (900 per hemisphere) at 110% phosphene threshold (PT) to the bLG during 10 sessions over two weeks.A battery of surveys and assessments, including a visual perceptual test related to cortical hyperexcitability, were administered prior to rTMS, immediately following, and at 1and 3-months post-treatment.Results: Nine of 12 participants completed 10 rTMS sessions; one completed seven sessions and stopped due to symptomatic COVID-19; one participant completed a partial session and withdrew due to severe migraine.One participant withdrew before treatment due to travel.The average PT was 68%, and challenges in PT determination were noted.Nine of 12 participants had expected AE's (scalp tingling, headache, and/or dizziness) with headaches being most common.Two of the 12 had unexpected AEs (both with shoulder twitch/extremity tingling).None had serious AE.Conclusions: Overall, rTMS was generally well tolerated; most AEs were expected and reported as mild and tolerable.Travel and the COVID-19 pandemic limited study participation.PT determination, coil orientation, and participant position should be investigated as potential contributors to AE.