Graduated and sequential propagation in mesial temporal epilepsy: analysis with scalp ictal EEG

The purpose of this study was to describe the most common types of discharge propagation in mesial temporal epilepsy and to determine whether there are particular propagation characteristics that suggest a lesser degree of temporal excitability. This is a retrospective and analytical observation study with an open historical cohort of 22 patients with mesial temporal epilepsy among whom 75 complex partial seizures were recorded, with or without secondary generalization. Of the 75 seizures, 64 were of regionalized-lateralized onset, and their distance propagation sequence was analyzed. The onset, localization, and propagation sequence were identified. The patients were classified into three groups according to seizure propagation: group I (G I), with propagation to the ipsilateral hemisphere only; group II (G II), with gradual and sequential ipsilateral and contralateral propagation; and group III (G III), with total hemisphere toward the contralateral propagation. The G I and G II seizures were significantly associated with unitemporal interictal EEGs in comparison with the G III seizures (P = 0.00277). At the same time, the epilepsy was easier to control in G I and II, whereas all the G III patients were intractable (P = 0.0094). The G I and II had a greater tendency to be patients with pure mesial sclerosis than the G III. Most of the mesial temporal seizures observed showed propagation limited to the ipsilateral hemisphere at the onset of the discharge or a graduated sequential propagation. A lesser degree of unitemporal excitability was suggested in both situations, without significant alterations in the propagation times of the ipsilateral and contralateral epileptic discharges and relative preservation of the usual propagation pathways. The reverse situation was suggested among patients with total contralateral propagation seizures.