We determined how noninvasive presurgical data relate to prognosis aft
er temporal lobectomy in patients with independent bilateral temporal
lobe (IBTL) complex partial seizures on the intracranial electroenceph
alogram (EEG). Between 1986 and 1994, 28 patients had IBTL seizures on
intracranial EEG. Fifteen of these 28 patients underwent temporal lob
ectomy and 13 were not offered surgery. Of the 15 patients who had sur
gery, 10 patients became seizure-free. Magnetic resonance imaging (MRI
) and the Wada test were the only variables associated with a seizure-
free outcome. Seven of 10 seizure-free patients had a lateralized Wada
result or the presence of unilateral hippocampal sclerosis, whereas n
one of the patients with persistent seizures had either of these findi
ngs. Variables not found to be predictive of a seizure-free outcome in
cluded location of scalp interictal spikes, degree of seizure-onset la
terality, presence of early epilepsy risk factor, duration of epilepsy
, and full-scale intelligence quotient. We conclude that MRI and the W
ada test provide information of prognostic value in patients with bila
teral temporal seizures independent of intracranial EEG data.