Presurgical evaluation for partial epilepsy: relative
contributions of chronic depth-electrode recordings versus FDG-PET and
scalp-sphenoidal ictal EEG
Source: Neurology
1990 Nov;40(11):1670-1677.
Author: Engel J;Henry TR;Risinger MW;Mazziotta JC;Sutherling WW;Levesque
MF;Phelps ME PubMed ID: 2122275
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