Objective: To explore and validate a novel stimulation and analysis paradigm p roposed to monitor spatial distribution and temporal changes of the excitability state in patients with temporal lobe epilepsy (TLE). Methods: We use intermitte nt pulse stimulation in the frequency range 10-20 Hz. A quantitative measure of spectral phase de-modulation, the relative phase clustering index (rPCI) was a pplied to the evoked EEG signals,measured from electrodes implanted in the hippo campal formation.Results: We found that in the interictal periods, high values o f rPCI recorded from specific sites were correlated with the most probable seizu re onset sites (SOS). Furthermore we found that high values of rPCI from certain locations correlated with shorter time intervals to the next seizure. Conclusio ns:Our clinical findings indicate that although the precise moment of ictal tran sitions is in general unpredictable, it maybe possible to estimate the probabili ty of occurrence of some epileptic seizures. Significance: The use of the rPCI f or probabilistic forecasting of upcoming epileptic seizures is warranted.rPCI me asurements may be used to guide interventions with the aim of modifying local ti ssue excitability that ultimately might prevent ictal transitions. Objective: To explore and validate a novel stimulation and analysis paradigm p roposed to monitor spatial distribution and temporal changes of the excitability state in patients with temporal lobe epilepsy (TLE). Methods: We use intermitte nt pulse stimulation in the frequency range 10-20 Hz. A quantitative measure of spectral phase de-modulation, the relative phase clustering index (rPCI) was a pplied to the evoked EEG signals, measured from electrodes implanted in the hippo campal formation. Results: We found that in the interictal periods, high values ​​of rPCI recorded from specific sites were correlated with the most probable seizure of onset sites (SOS). Conclusio ns: Our clinical findings indicate that high values ​​of rPCI from certain locations correlated with shorter time intervals to the next seizure although the precise moment of ictal tran sitions is in general unpredictable, it maybe possible to estimate the probabili ty of occurrence of some epileptic seizures. Significance: The use of the rPCI f or probabilistic forecasting of upcoming epileptic seizures is warranted. rPCI me asurements may be used to guide interventions with the aim of modifying local ti ssue excitability that ultimate might ictal transitions.