Functional MRI predicts memory performance after right mesiotemporal epilepsy surgery.
OBJECTIVE
Anterior temporal lobe resection (ATR) is a treatment option in drug-resistant epilepsy. An important risk of ATR is loss of memory because mesiotemporal structures contribute substantially to memory function. We investigated whether memory-activated functional MRI (fMRI) can predict postoperative memory loss after anterior temporal lobectomy in right-sided medial temporal lobe epilepsy (MTLE).


METHODS
We included 16 patients (10 women) aged 16-54 years. The mean age at epilepsy onset was 12.5 years (range, 1-26 years). The patients' mean Wechsler IQ score was 95.2 (range, 62-125). The activation condition of fMRI consisted of retrieval from long-term memory induced by self-paced performance of an imaginative walk. All but one patient had left-sided speech dominance according to speech-activated fMRI. Outside the scanner, we evaluated the pre- and postoperative visual memory retention by using Rey Visual Design Learning Test.


RESULTS
We found a correlation between the preoperative asymmetry index of memory-fMRI and the change between pre- and postsurgical measures of memory retention. Reduced activation of the mesiotemporal region ipsilateral to the epileptogenic region correlated with a favorable memory outcome after right-sided ATR.


CONCLUSIONS
In light of the postoperative results, the theoretical implication of our study is that fMRI based on a simple introspective retrieval task measures memory functions. The main clinical implication of our study is that memory-fMRI might replace the invasive Wada test in MTLE by using a simple fMRI paradigm. Predictive power, however, will be studied in larger patient samples. Other studies are required for left-sided MTLE and neocortical epilepsies to assess the clinical usefulness of memory-fMRI.
Janszky
Jozsef
J
Mara Hospital, Bethel Epilepsy Centre Bielefeld, Germany.
Jokeit
Hennric
H
Kontopoulou
Konstantina
K
Mertens
Markus
M
Ebner
Alois
A
Pohlmann-Eden
Bernd
B
Woermann
Friedrich G
FG
D000293:Adolescent; D000328:Adult; D004833:Epilepsy, Temporal Lobe / Q000601:surgery*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000706:statistics & numerical data; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000706:statistics & numerical data*; D008297:Male; D008569:Memory Disorders / Q000175:diagnosis; D008875:Middle Aged; D011183:Postoperative Complications / Q000175:diagnosis; D011237:Predictive Value of Tests