Interpretation of Wada memory test for lateralization of seizure focus by use of (99m)technetium-HMPAO SPECT.
OBJECTIVE
Although the intracarotid amobarbital procedure (IAP) or Wada test is useful in lateralizing seizure focus in patients with temporal lobe epilepsy (TLE), the results of the IAP memory test are frequently nonlateralizing. An insufficient suppression of the medial temporal region contralateral to the seizure focus may contribute to the failure of lateralization. We tried to correlate IAP memory results with the functional changes in the contralateral medial temporal region as measured by single photon emission computed tomography (SPECT) during IAP.


METHODS
We performed a (99m)technetium-(Tc) hexamethylene-propylene-amine-oxime (HMPAO) brain SPECT in 19 medial TLE patients during a contralateral IAP (sodium amobarbital injected contralateral to the seizure focus). Regional cerebral blood flow (rCBF) was measured in the contralateral medial temporal region. The amount of decrease in the rCBF was calculated by subtracting the previous measurement from the one obtained with the interictal SPECT.


RESULTS
Ten (53%) patients passed and nine (47%) failed the contralateral IAP. The mean percentage decrease in rCBF was 5.3+/-5.3%. There was a significant negative correlation between a decrease in the rCBF and the IAP memory-retention score by Spearman correlation (p = -0.53: p<0.021). Patients with smaller decreases in rCBF (<5%) more frequently passed the contralateral IAP memory test than did those with larger decreases (80 vs. 22%; p<0.023).


CONCLUSIONS
We suggest that an insufficient suppression of the contralateral medial temporal function is partly responsible for nonlateralizing IAP memory tests. An IAP-SPECT may be useful in interpreting IAP memory tests for the lateralization of seizure focus in TLE patients.
Kim
B G
BG
Department of Neurology, College of Medicine, Seoul National University, Korea.
Lee
S K
SK
Kim
J Y
JY
Kang
D W
DW
Lee
W
W
Song
H
H
Lee
D S
DS
D000328:Adult; D004292:Dominance, Cerebral; D005260:Female; D006801:Humans; D008297:Male; D008568:Memory; D009483:Neuropsychological Tests; D019275:Radiopharmaceuticals; D012640:Seizures / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D019690:Technetium Tc 99m Exametazime; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods
D019275:Radiopharmaceuticals; D019690:Technetium Tc 99m Exametazime