Presurgical evaluation of temporal lobe epilepsy using interictal temporal spikes and positron emission tomography
M. W. Chee, H. H. Morris 3rd, M. A. Antar, P. C. Van Ness, D. S. Dinner, P. Rehm and V. Salanova
Department of Neurology, Cleveland Clinic Foundation, OH 44195-5227.
OBJECTIVE--Our goal was to determine the role of fludeoxyglucose F
18-positron emission tomography (18FDG-PET) and interictal temporal spikes
in lateralizing the epileptogenic region in patients who (1) were diagnosed
as having temporal lobe epilepsy based on clinical symptoms and exclusively
temporal interictal spikes and (2) did not have a structural lesion on
magnetic resonance imaging. DESIGN--This was a retrospective study of 40
consecutive patients fulfilling the above criteria who underwent 18FDG-PET
scanning. A firm electrophysiologic diagnosis and 1 complete year of
postsurgical follow-up, where applicable, were required. Outcome measures
included surgical outcome and final electrophysiologic diagnosis.
RESULTS--Unilateral, interictal temporal spikes (ITS) were present in 33
(82.5%) of 40 patients. Seven patients (17.5%) had bitemporal, independent
spikes. Thirty-one (77.5%) of 40 patients had unilateral temporal
hypometabolism (TH). Twenty-eight (70%) patients had concordant TH and ITS.
One year after surgery, 31 of 33 patients with unilateral ITS were greatly
improved; two of five who had bitemporal ITS showed similar improvement. In
28 patients, unilateral TH and unilateral ITS were concordant. The paired
result always concurred with the final neurophysiologic assessment.
Surgical outcome between patients with 18FDG-PET showing unilateral TH (26
of 30 greatly improved) and those not showing unilateral TH (six of eight
greatly improved) was not significantly different. CONCLUSION--In temporal
lobe epilepsy not associated with a mass lesion, unilateral ITS are
reliable lateralizing features and suggest a good surgical outcome. Use of
18FDG-PET provides corroborative lateralizing information but 18FDG-PET
that fails to show unilateral TH does not preclude a good surgical outcome.
