Abstracts

Rationale: Afterdischarges (ADs) can occur during functional localization testing using cortical stimulation, and thus interfere with performing and interpreting this testing. Brief pulses of electrical stimulation (BPS; Neurology 53:2073-2081, 1999) can sometimes abort ADs, but not always. We previously reported that mental calculations (2-digit subtraction) could end runs of ADs in one patient. It would be important to know whether this effect is limited to mental calculations, or whether other cognitive activities can have similar effects. Methods: We assessed patients with implanted subdural electrodes and who were undergoing stimulation testing to localize cortical areas controlling motor, sensory, or language functions. We assessed the effects of calculations on ending ADs and also assessed other forms of mental activation (e.g. spelling words backwards). Results: Mental activation, including both calculations and spelling words backwards, could be effective when BPS had not been effective on the same run of ADs. Mental activation also could be effective in aborting ADs when BPS had not been used. We will illustrate this effect with video. Not all forms of mental activation were effective. For example, ADs could persist during standard language tasks, such as reading and naming. Conclusions: Some forms of mental activation can abort ADs in some patients. This could be useful for stopping ADs during clinical testing, and possibly could be useful for terminating runs of epileptiform activity under other circumstances.