Comparison of Cheek Electrode with Sphenoidal Electrodes for Identification of Ictal Onset Activity

BACKGROUND: The sphenoidal electrodes are used to localize epileptiform discharge in temporal lobe epilepsy. However, the insertion of the sphenoidal electrodes is a semi-invasive procedure that is painful and uncomfortable. The sensitivity of sphenoidal electrodes varies depending on the tip position of the wire electrode. We investigated the usefulness of cheek electrodes for the identification of the ictal onset activity in temporal lobe epilepsy, and then compared it with that of sphenoidal electrodes. METHODS: Both the cheek electrodes and the sphenoidal electrodes were positioned and seizure monitoring was performed on 17 patients suffering from complex partial seizures. Remontaging the EEG using the sphenoidal and cheek electrodes produced EEG printouts for each seizure, alternatively. Two neurologists interpreted all of the records independently. The EEGs were used to lateralize and localize the ictal onset activity and time of onset of ictal activity. RESULTS: There were a total of 95 seizures in the 17 patients. The overall amplitude recorded by cheek electrodes was slightly lower than sphenoidal electrodes. But there were no significant differences between these two types of electrodes in detection of ictal onset. CONCLUSIONS: The cheek electrodes are comparable with the sphenoidal electrodes in its effectiveness for the localization of ictal activity in patients with complex partial seizures. It is a relatively comfortable technique. It may replace sphenoidal electrodes for the identification of ictal onset activity in complex partial seizures.

Intracranial Ictal Electroencephalographic Patterns in Parietal Lobe Epileptic Seizures : Correlation with Surgical Outcome

BACKGROUNDS: Parietal lobe epilepsy is uncommon and its intracranial ictal EEG findings have not been well elucidated. We investigated the ictal EEG patterns of epilepsy originating from the parietal lobe and its adjacent areas recorded by intracranial subdural electrode arrays. METHODS: The following intracranial ictal EEG patterns from twenty patients who underwent epilepsy surgery for medically intractable parietal lobe epilepsy were studied: 1) Anatomical ictal onset area [pure parietal (PP), combined parietal and extraparietal, such as fronto-parietal, temporo-parietal, etc. (EP)], 2) localization within the parietal lobe, 3) extent of the ictal onset zone, 4) the number of ictal onset zones, 5) frequency and waveform of ictal onset rhythms, and 6) type of spreading. RESULTS: Twelve patients (60%) were seizure-free (5 from PP, 7 from EP) and 8 were with persistent seizures (3 from PP, 5 from EP). Eight patients (40%) had ictal onset from PP and 12 were from EP. There were! Significant correlations with surgical outcome (p<0.05) in two variables: extent of ictal onset zone and type of spread. Patients with focal onset zones (n=9) showed better outcomes (eight are seizure-free) than those with wide ictal onset zones (4 out of 7 are seizure-free). Patients with slow spreading patterns showed better outcomes (12 from 16 are seizure-free) than those with fast spreading outcomes (all of them had persistent seizures). CONCLUSIONS: The extent of ictal onset zones correlates with surgical outcomes. The patterns of intracranial ictal EEG are helpful in predicting the surgical outcomes for parietal lobe epilepsy. (J Korean Neurol Assoc 19(5):478~484, 2001)