Reduction of EEG myogenic artifact with botulinum toxin during video-EEG monitoring

Purpose: To determine whether EEG myogenic artifact during video-EEG monitoring (VEM) is reduced with targeted scalp botulinum toxin (BTX-A) injections. Methods: Twelve consecutive patients scheduled for presurgical VEM were treated 2-3 weeks before admission with subcutaneous BTX-A injections at specific EEG electrode locations. On the basis of clinical data available before VEM, four subjects were treated unilaterally (group 1) and eight bilaterally (group 2). BTX-A efficacy was assessed quantitatively in group 1 subjects by comparing high-frequency (20-100 Hz) power at homologous "treated" and "untreated" electrodes during voluntary forceful jaw closure. The clinical impact of BTX-A treatment was assessed by determining whether ≥5 of the first 10 s of each ictal recording was obscured by muscle artifact, and whether residual myogenic artifact on BTX-A-"treated" electrodes rendered these ictal EEG segments impossible to interpret. Results: BTX-A treatment reduced high-frequency power by a mean of 53% at electrodes T3/T4 and 52% at electrodes F7/F8. None of 49 ictal EEGs had ≥5 of the first 10 s obscured by myogenic artifact, and all of these ictal epochs were interpretable. Adverse events were limited to two subjects who complained of transient difficulty chewing tough foods. Conclusions: Scalp-muscle BTX-A treatment before VEM significantly reduces myogenic artifact in subsequent EEG recordings, including ictal EEG. The clinical utility of this technique for improved or more-rapid seizure localization will be determined only by large, blinded, prospective trials.