American Clinical Neurophysiology Society Technical Standards for Electrical Stimulation With Intracranial Electrodes for Functional Brain Mapping and Seizure Induction

Purpose: These American Clinical Neurophysiology Society technical standards suggest best practices for electrical stimulation mapping (ESM) with subdural and stereotactic depth electrodes for seizure induction and mapping of brain function. Methods: A working group was convened from American Clinical Neurophysiology Society membership with expertise in ESM. PubMed searches were performed to identify pertinent peer-reviewed literature. Recurrent meetings reviewed progress, built consensus by discussion, and developed evidence-based recommendations to the extent possible. Recommendations: Stimulators used for ESM should have sufficient dynamic range, ability to interrupt a stimulus train, and ictal disrupt mechanism(s). Charge density should be calculated for the specific electrodes and ESM settings, the maximum safe limits being 52 to 57 mC/cm²/phase for subdural electrodes and not established for stereotactic depth electrodes. Subdural ESM for functional mapping is typically performed at 50-Hz pulse frequency, 200- to 300-ms pulse width, 2- to 8-s train duration, and 1- to 20-mA current strength. Stereo ESM is commonly performed using 2 different pulse frequencies: 1 Hz (300-500 ms pulse width, train duration up to 30 s, and often a constant current of 3-5 mA), and 50 Hz (100-500 ms pulse width, train duration 2-8 s, and 0.5-10 mA current intensity). Conclusions: This guideline provides technical standards for the performance of ESM, which will likely evolve over time with advances in technology and additional evidence (also see Graphical Abstract).