Presurgical evaluation for partial epilepsy

Abstract

One hundred fifty-three patients with medically refractory partial epilepsy underwent chronic stereotactic depth-electrode EEG (SEEG) evaluations after being studied by positron emission tomography (PET) with 18F-fluorodeoxyglucose (FDG) and scalp-sphenoidal EEG telemetry. We carried out retrospective standardized reviews of local cerebral metabolism and scalp-sphenoidal ictal onsets to determine when SEEG recordings revealed additional useful information. FDG-PET localization was misleading in only 3 patients with temporal lobe SEEG ictal onsets for whom extratemporal or contralateral hypometabolism could be attributed to obvious nonepileptic structural defects. Two patients with predominantly temporal hypometabolism may have had frontal epileptogenic regions, but ultimate localization remains uncertain. Scalp-sphenoidal ictal onsets were misleading in 5 patients. For 37 patients with congruent focal scalp-sphenoidal ictal onsets and temporal hypometabolic zones, SEEG recordings never demonstrated extratemporal or contralateral epileptogenic regions; however, 3 of these patients had nondiagnostic SEEG evaluations. The results of subsequent subdural grid recordings indicated that at least 1 of these patients may have been denied beneficial surgery as a result of an equivocal SEEG evaluation. Weighing risks and benefits, it is concluded that anterior temporal lobectomy is justified without chronic intracranial recording when specific criteria for focal scalp-sphenoidal ictal EEG onsets are met, localized hypometabolism predominantly involves the same temporal lobe, and no other conflicting information has been obtained from additional tests of focal functional deficit, structural imaging, or seizure semiology.

Presurgical multimodality neuroimaging in electroencephalographic lateralized temporal lobe epilepsy

“…Our results comparing FDG-PET with HV replicate independently those published by Gaillard and colleagues [6]. These results, along with the finding that false lateralizations with FDG-PET are extremely rare in TLE [1,33], indicate that FDG-PET can be used to confirm lateralization when other imaging or clinical findings are equivocal.…”

“…Our results comparing FDG-PET with HV replicate independently those published by Gaillard and colleagues [6]. These results, along with the finding that false lateralizations with FDG-PET are extremely rare in TLE [1,33], indicate that FDG-PET can be used to confirm lateralization when other imaging or clinical findings are equivocal.Using 1 H-MRSI lateralization data together with HV yielded a total MR lateralization sensitivity comparable with that of FDG-PET. As a result, addition of 1 H-MRSI to presurgical MR protocols should add lateralizing data above that of only MRI and eliminate the need for a PET study in additional patients with cryptogenic TLE.…”

“…To minimize the requirement for intracranial electrodes and to localize the epileptogenic zone with increased confidence, 2-[ 18 F]fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) and magnetic resonance imaging (MRI) are used to provide confirmatory localizing information. Relative temporal lobe (TL) hypometabolism on FDG-PET and hippocampal atrophy or prolonged T2 signal on MRI predict reliably lateralization of the epileptogenic temporal lobe [1][2][3][4][5]. Localized TL hypometabolism on FDG-PET is reported to be more sensitive than the detection of lateralized abnormality on MRI [3]; however, little has been published on the direct comparison of FDG-PET to advanced MRI and magnetic resonance spectroscopic imaging (MRSI) techniques.…”

Temporal lobe epilepsy with mesial temporal sclerosis: hippocampal neuronal loss as a predictor of surgical outcome

“…The agreement records of the MRI, ictal and interictal EEG, neuropsychological tests and positron emission tomography pointing to a unilateral and localized epileptogenic zone have already been shown to favor surgical prognosis [12][13][14] .…”

Cortical abnormalities in epilepsy revealed by local EEG synchrony

“…Analysis of intracranial EEG (ICEEG) ictal recordings to identify the epileptogenic zone is generally more specific than information provided by seizure semiology, neuroimaging or neuropsychological testing (Engel, Henry et al 1990). Visual interpretation of the intracranial EEG (ICEEG) is a clinically reliable tool for identifying the epileptogenic zone in mesial temporal epilepsy (Pacia and Ebersole 1999) but has more variable success in predicting surgical control of neocortical seizures, particularly in cases where neuroimaging does not show focal abnormalities (Alarcon, Binnie et al 1995;Ebersole 1999;Jung, Pacia et al 1999).…”