Abstracts

Rationale: Afterdischarges commonly occur as an unwonted side effect during cortical stimulation. Little is known, however, regarding the mechanisms underlying their occurrence or their termination.Methods: We performed cortical stimulation via subdural electrodes for functional localization in a patient with intractable epilepsy. When afterdischarges occurred, we used brief pulse stimulation (Neurology 53:2073-2081, 1999) or arithmetic calculation in an effort to stop the afterdischarges.Results: Arithmetic calculation could abort afterdischarges, even when brief pulse stimulation could not. This effect occurred at multiple sites and on multiple days. Conclusions: Arithmetic calculations can abort afterdischarges in at least some circumstances. This could be due to mental activation, however, afterdischarges also could occur during naming, following commands, and other language tasks. This may be a novel means of stopping afterdischarges when they occur, and may also provide clues into mechanisms underlying the occurrence and termination of spontaneous seizures.