Relative utility of sphenoidal and temporal surface electrodes for localization of ictal onset in temporal lobe epilepsy.
OBJECTIVE
To compare localization of ictal onsets in patients with possible temporal lobe epilepsy (TLE) using true temporal electrodes (TE), at positions T1 and T2, and sphenoidal electrodes (SpE).


METHODS
A total of 101 ictal tracings in 31 patients with possible TLE were independently reviewed by two readers and graded as meeting (TE+, SpE+) or not meeting (TE-, SpE-) strictly-defined mesial temporal onset criteria. TE and SpE were reviewed in separate montages, with ad lib adjustment of filters and sensitivity. Discrepancies between TE and SpE were noted, with inter-reader disagreements resolved by a third reviewer.


RESULTS
All seizures scored as SpE+ were also scored as TE+, with one exception. The sole SpE+/TE- seizure did not add incremental useful information in that patient, who had other, similar seizures which were TE+. Five seizures in 4 patients were scored as TE+ and SpE-, most due malfunction of SpE prior to seizure onset. One of these seizures was scored TE+/SpE- in a patient believed to have neocortical epilepsy.


CONCLUSIONS
In this series, SpE were unnecessary to detect seizures which meet strict mesial temporal onset criteria and did not yield useful information for surgical evaluation beyond that provided by TE. It remains unclear if SpE are more helpful than TE in distinguishing lateral from mesial ictal onset. Digital review of ictal tracings may resolve discrepancies between TE and SpE.
Mintzer
Scott
S
Department of Neurology, Seizure Disorder Center, UCLA School of Medicine, Los Angeles, CA, USA. scottmintzer@northwestern.edu
Nicholl
Jeffrey S
JS
Stern
John M
JM
Engel
Jerome
J
D000293:Adolescent; D000328:Adult; D004566:Electrodes; D004569:Electroencephalography / Q000379:methods*; D004833:Epilepsy, Temporal Lobe / Q000175:diagnosis* / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011930:Reaction Time; D012189:Retrospective Studies; D013100:Sphenoid Bone; D013701:Temporal Bone; D013702:Temporal Lobe / Q000503:physiopathology