A Safe and Effective Paradigm to Functionally Map the Cortex in Childhood

Conventional cortical stimulation based on pulses of fixed duration briefer than the chronaxie rarely elicit responses in infants and young children. We developed a stimulation paradigm that relies on increments in both stimulus intensity and pulse duration. This approach ensures that stimulation parameters converge to the chronaxie by mathematically minimizing the energy required to elicit a response. In six patients, this paradigm successfully elicited clinical responses and/or afterdischarges at thresholds 5-8 mA below the standard paradigm and at up to 64% lower energy levels. Furthermore, three patients under age 5 years who did not respond to maximal fixed duration stimulation demonstrated afterdischarges and clinical responses when longer pulse durations were utilized. These findings indicate that a paradigm based on dual increments is effective for cortical mapping in children. Furthermore, by ensuring responses at lower energy levels, it may be more efficient for mapping the cortex at all ages.