The Log-time-spectral-distance (LTSD) is a novel intra-patient measurement of seizure similarity first applied to Electroencephalography (EEG) analysis by Mark Lippmann. It is an adaptation of the log spectral distance (LSD) which is a distance measure between two spectra.

LTSD Seizure Analyzer is a LTSD based visualization tool integrated with the IEEG portal website, which enable physicians and scientists to assess seizure similarity in a new way.