Preoperative IQ predicts seizure outcomes after anterior temporal lobectomy.
OBJECTIVE
IQ tests are frequently used in the preoperative neuropsychological assessment of candidates for anterior temporal lobectomy (ATL). We reviewed IQ test results and surgery outcomes to evaluate the roles of IQ tests in the preoperative work-up.


METHODS
A total of 205 adult patients who had undergone ATL and whose seizure outcomes were followed for 2 years after surgery were included. The short form WAIS-R was used to estimate intelligence. Multiple linear regression and logistic regression analyses were used to examine the variables for IQ and seizure outcomes.


RESULTS
Education, duration of epilepsy and gender were factors that accounted for 24.6% of the variance in the full-scale IQ (FSIQ) scores. The verbal IQ and performance IQ discrepancies at various magnitudes could not lateralize the seizure foci. Freedom of seizure was noted in 128 (62.4%) of the patients. Seizure outcomes, however, correlated with the preoperative FSIQ. After adjustment for variables that affect seizure outcomes, the FSIQ was an independent predictor of postoperative seizure outcomes (OR 1.04, 95% CI 1.01-1.06, p=0.003). Of patients who had FSIQ lower than 70, 50% became free from seizures by 2 years after surgery.


CONCLUSIONS
In our study, IQ tests were unable to lateralize seizure foci but may serve as an independent predictor of postoperative seizure outcomes. Since a longer duration of epilepsy had deleterious effects on intelligence, earlier surgical intervention might better preserve neuropsychological function and, consequently, allow better seizure control after ATL. Nonetheless, patients with lower IQ scores could still benefit from ATL.
Yu
Hsiang-Yu
HY
Department of Neurology, Taipei Veterans General Hospital, National Yang-Ming University, Taiwan.
Shih
Yang-Hsin
YH
Su
Tung-Ping
TP
Lin
Ker-Nen
KN
Yiu
Chun-Hin
CH
Lin
Yung-Yang
YY
Kwan
Shang-Yeong
SY
Chen
Chien
C
Yen
Der-Jen
DJ
D000328:Adult; D038481:Anterior Temporal Lobectomy / Q000009:adverse effects*; D004833:Epilepsy, Temporal Lobe / Q000150:complications / Q000601:surgery*; D005260:Female; D006801:Humans; D007360:Intelligence; D008297:Male; D009483:Neuropsychological Tests; D011183:Postoperative Complications / Q000209:etiology*; D057234:Preoperative Period; D012640:Seizures / Q000209:etiology / Q000601:surgery*; D014888:Wechsler Scales