A Preliminary Assessment on Reproducibility of Triggered Electromyography During Selective Dorsal Rhizotomy.

Abstract

Background and objectives: Selective dorsal rhizotomy (SDR) reduces spasticity in children with spastic cerebral palsy (CP). Intraoperative neurophysiology, triggered electromyography (trigger-EMG) is crucial in guiding sensory rootlet selection, but its reproducibility during SDR surgery has not been fully investigated. The objective of this study was to evaluate the reproducibility of trigger-EMG during SDR performed in children with spastic CP.

Methods: A retrospective review was performed for cases where dorsal roots were stimulated twice 1 to 2 minutes apart during SDR using a specific protocol. With single-pulse stimulation of 0.2 ms width having a gradually increasing intensity from 0.01 mA until the EMG amplitude is >200 μV. Criteria were established to evaluate trigger-EMG reproducibility.

Results: This study showed that the reproducibility of trigger-EMG was excellent, as the most responsive channels in the second stimulation trial were the same as those in the first one in 90.1% of the roots stimulated. In addition, the 3 most responsive channels were mostly the same between the first and second stimulation trials in 96.9% of the roots tested. Furthermore, when comparing the evoked EMG pattern since the beginning to the end point between the 2 stimulation trials in all 131 roots, the amplitudes of trigger-EMG in 3 most responsive channels were similar to each other, particularly the most responsive one. Amplitudes of each phase in each EMG evoked were also similar to each other.

Conclusion: The excellent reproducibility of trigger-EMG, as demonstrated by its consistent activation of specific spinal motor circuits, provides a solid foundation for future research. Further investigation into the underlying electrophysiological mechanisms of this reproducibility could inform the development of more refined stimulation protocols and data analysis techniques. These advancements hold promise for enhancing the accuracy of dorsal root selection during SDR and ultimately improving clinical outcomes for patients with spastic CP.