Tonic phase seizure is characterized by a short tonic phase followed by a long clonic phase. Studies show an inverse relationship between the two phases. This inverse relationship can be used to predict the duration and dynamics of tonic-clonic seizures.
 
 The clonic phase may be determined by the low frequency band.  https://epilepsyseizure.co.nz/  This band may have a bandwidth that is determined by a characterization pattern that discriminates muscle-related electrical signals from brain signals. During clonic phase seizure activity, this frequency band is elevated. In some systems, this bandwidth may be a range from 2 Hz to 16 Hz.
 
 A time-point extraction module is included in a seizure detection system. This module is configured to detect the beginning and ending points of a seizure by comparing the output signal with a predetermined threshold value.
 
 Tonic-clonic seizures begin with a gradual increase in power during the tonic phase. Some embodiments of these methods and systems use the slope of the change in power during the tonic phase as a means of predicting other characteristics of seizures.
 
 In some systems, a time point T0 is identified as the time of the first burst in the clonic phase. This burst may occur 30 seconds before the seizure is detected. It is also possible to identify only the starting point of the clonic phase. However, clonic phase data may be obscured by other reasons.
 
 The energy calculation module may include counters and peak detectors. These counters and peak detectors may be configured to measure the energy of the seizure.