Usefulness of 123I-iomazenil single-photon emission computed tomography in discriminating between mesial and lateral temporal lobe epilepsy in patients in whom magnetic resonance imaging demonstrates normal findings.
OBJECTIVE
To provide greater accuracy in determining the epileptogenic zone during preoperative evaluation, the authors retrospectively examined 123I-iomazenil single-photon emission computed tomography (IMZ SPECT) studies obtained in patients with temporal lobe epilepsy (TLE) in whom there was no evidence of an abnormality on magnetic resonance (MR) images.


METHODS
Twelve patients, seven with mesial TLE (MTLE) and five with lateral TLE (LTLE), satisfied the criteria for inclusion in the study. The IMZ SPECT findings in these patients were reviewed retrospectively, and a comparison was made between findings in patients with MTLE and those in patients with LTLE.


RESULTS
The IMZ SPECT studies demonstrated decreased IMZ uptake in the ipsilateral mesial temporal region and the anterobasal temporal lobe in all patients who had MTLE on only one side. On the other hand, IMZ SPECT examinations revealed low IMZ uptake in the ipsilateral lateral temporal lobe in four of five patients with LTLE in whom abnormal findings were restricted to the lateral neocortex. In the remaining patient with LTLE, abnormally low IMZ uptake was found in both mesial and lateral temporal lobes, although pure LTLE was diagnosed by an invasive electroencephalographic evaluation; this patient's habitual seizures continued even after temporal lobectomy, although his mesial structures were spared.


CONCLUSIONS
The authors report characteristics of IMZ SPECT findings that differed between patients with MTLE and those with LTLE. The IMZ SPECT examinations proved useful for preoperative evaluation and, to a certain extent, for discrimination between MTLE and LTLE in cases in which MR imaging demonstrated normal findings. The results of this study suggest that IMZ SPECT findings may reflect localization of the epileptogenic zone.
Umeoka
Shuichi
S
Department of Neurological Surgery, National Epilepsy Center, Shizuoka Institute of Epilepsy and Neurological Disorders, Urushiyama, Shizuoka, Japan. umesh@szec.hosp.go.jp
Matsuda
Kazumi
K
Baba
Koichi
K
Usui
Naotaka
N
Tottori
Takayasu
T
Terada
Kiyohito
K
Usui
Keiko
K
Nakamura
Fumihiro
F
Inoue
Yushi
Y
Fujiwara
Tateki
T
Mihara
Tadahiro
T
D000328:Adult; D004569:Electroencephalography; D004833:Epilepsy, Temporal Lobe / Q000000981:diagnostic imaging* / Q000473:pathology; D005260:Female; D005442:Flumazenil / Q000031:analogs & derivatives*; D006801:Humans; D007457:Iodine Radioisotopes; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D015899:Tomography, Emission-Computed, Single-Photon
D007457:Iodine Radioisotopes; D005442:Flumazenil; C063038:iomazenil