Abstract: Improved methods and devices are provided for detecting and/or predicting the onset of an undesirable physiological event or neural state, such as an epileptic seizure, to facilitate rapid intervention with a treatment therapy such as neurostimulation or drug therapy. The methods and devices involve monitoring the patient's body temperature, preferably by an implanted temperature sensor, to detect a change in a body temperature parameter over a first time period. The temperature parameter change may comprise an increase or decrease in the patient's body temperature over a first time period, time rate of change of body temperature over a first time period, a moving average temperature over a first time period, an increase or decrease in body temperature exceeding a target temperature over a first time period, an elevated or reduced body temperature over first time period, or a temperature stability parameter over a first time period.