Proton MRS may predict AED response in patients with TLE.
OBJECTIVE
To compare relative N-acetylaspartate (NAA) measurements in temporal lobe epilepsy (TLE) patients with good response to the first trial of antiepileptic drugs (AEDs) (an important prognostic factor) to TLE patients who failed the first AED monotherapy and required further AED trials with monotherapy or polytherapy.


METHODS
We studied 25 consecutive TLE patients who responded to first AED (responders) and 21 who did not (failure-group), as well as 27 controls. Patients were seen regularly in our Epilepsy Service and underwent electroencephalography (EEG) investigation, high-resolution magnetic resonance imaging (MRI), and single-voxel proton MR spectroscopy. Voxels were tailored to the medial temporal region on each side and involved the anterior hippocampus.


RESULTS
Analysis of variance (ANOVA) demonstrated significant variation of NAA/creatine (NAA/Cr) values in both hippocampi, ipsilateral and contralateral to the EEG focus (p < 0.001 and p = 0.021) across the groups. Pairwise post hoc comparisons showed reduced NAA/Cr in both hippocampi of failure-group compared to controls (p < 0.001) and compared to responders (p < 0.05), but not between the controls and responders. Individual analyses showed NAA/Cr ratios lower than 2 SDs (standard deviations) below the mean of controls in 9 of 21 patients (42.8%) in the failure-group (6 with unilateral and 3 with bilateral reduction) but in none of the responders.


CONCLUSIONS
These results indicate that patients with TLE who respond well to the first AED have significantly less evidence of neuronal and axonal damage/dysfunction compared to those who are refractory to the first AED trial.
Department of Neurology, FCM, University of Campinas - UNICAMP, Campinas, São Paulo, Brazil.
Bruno A G
BA
Campos
Clarissa L
CL
Yasuda
Gabriela
G
Castellano
Elizabeth
E
Bilevicius
Li M
LM
Li
Fernando
F
Cendes
D000328:Adult; D000927:Anticonvulsants / Q000494:pharmacology / Q000627:therapeutic use*; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D004351:Drug Resistance; D004359:Drug Therapy, Combination; D004569:Electroencephalography; D004833:Epilepsy, Temporal Lobe / Q000175:diagnosis* / Q000188:drug therapy*; D005260:Female; D007839:Functional Laterality / Q000187:drug effects; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy / Q000706:statistics & numerical data; D008297:Male; D011379:Prognosis; D013702:Temporal Lobe / Q000187:drug effects / Q000378:metabolism; D016896:Treatment Outcome
D000927:Anticonvulsants; D001224:Aspartic Acid; C000179:N-acetylaspartate