The invention relates to detection of focal epileptiform activity. In order to accomplish an EEG-based mechanism that enables the detection and localization of focal epileptiform activity, a first plurality of brain wave signals is obtained from a subject (100) and a signal-specific measure indicative of the degree of epileptiform activity is determined (111-11N) for at least some of the first plurality of brain wave signals, thereby to obtain a second plurality of signal-specific measures. An indication of the presence of focal epileptiform activity is provided (12, 13, 15) based on the second plurality of signal-specific measures. This may involve, for example, a comparison (12) of the signal-specific measures. If significant mutual differences are detected in the measures, focal epileptiform activity is detected.
