Sixty-seven patients with temporal lobe epilepsy without circumscribed
, potentially epileptogenic lesions, who were studied with intracrania
l electrodes and who became seizure free following temporal lobectomy
were retrospectively evaluated with regard to preoperative scalp elect
roencephalographic (EEG) findings, neuropsychological test results, ne
uroimaging findings, results of surgery, and pathology of resected tis
sue. Interictal scalp EEG showed paroxysmal abnormalities during prolo
nged monitoring in 64 patients (96%). These were localized in the ante
rior temporal region in 60 (94%) of these 64 patients. Bilateral indep
endent paroxysmal activity occurred in 42% of the patients and was pre
ponderant over the side of seizure origin in half. Ictal EEG changes w
ere rarely detected at the time of clinical seizure onset, but lateral
ized buildup of rhythmic seizure activity during the seizure occurred
in 80% of patients. In 13%, the scalp EEG seizure buildup was, however
, contralateral to the side of seizure origin as subsequently determin
ed by depth EEG and curative surgery. Lateralized postictal slowing, w
hen present, was a very reliable lateralizing finding. Neuropsychologi
cal testing provided lateralizing findings concordant with the side of
seizure origin in 73% of patients. When neuropsychological testing pr
oduced discordant results or nonlateralizing findings, those patients
were usually found to have right temporal seizure origin. Intracarotid
amobarbital (Amytal) testing demonstrated absent or marginal memory f
unctions on the side of seizure onset in 63% of patients, but 26 patie
nts (37%) had bilaterally intact memory. In those patients who had mag
netic resonance imaging, it was very sensitive in detecting subtle med
ial temporal abnormalities. These abnormalities were present in 23 of
28 magnetic resonance images, and corresponded with mesial temporal sc
lerosis on pathological examination in all but 2 patients. Eighty-one
percent of the 51 patients who had adequate pathological examination o
f tissue had mesial temporal sclerosis. Forty-one patients with adequa
te pathological examination had histories of febrile seizures and of t
hese 38 (93%) had mesial temporal sclerosis.