Persistent seizures following left temporal lobe surgery are associated with posterior and bilateral structural and functional brain abnormalities.
OBJECTIVE
To perform a quantitative MRI and retrospective electrophysiological study to investigate whether persistent post-surgical seizures may be due to brain structural and functional abnormalities in temporal lobe cortex beyond the margins of resection and/or bilateral abnormalities in patients with temporal lobe epilepsy (TLE).


METHODS
In 22 patients with left TLE and histopathological evidence of hippocampal sclerosis, we compared pre-surgical brain morphology between patients surgically remedied (Engel's I) and patients with persistent post-surgical seizures (PPS, Engel's II-IV) using voxel-based morphometry (VBM). Routine pre-surgical EEG and invasive and non-invasive telemetry investigations were additionally compared between patient groups.


RESULTS
Results indicated widespread structural and functional abnormalities in patients with PPS relative to surgically remedied patients. In particular, patients with PPS had significantly reduced volume of the ipsilateral posterior medial temporal lobe and contralateral medial temporal lobe relative to surgically remedied patients. Furthermore, successful surgery was associated with clear anterior (89%) and unilateral (100%) temporal lobe EEG abnormalities, whilst PPS were associated with widespread ipsilateral (91%) and bilateral (82%) temporal lobe abnormalities.


CONCLUSIONS
We suggest that these preliminary data support the hypothesis that PPS after temporal lobe surgery are due to functionally connected epileptogenic cortex remaining in the ipsilateral posterior temporal lobe and/or in temporal lobe contralateral to resection.
Keller
Simon S
SS
The Magnetic Resonance and Image Analysis Research Centre (MARIARC), University of Liverpool, Pembroke Place, Liverpool L69 3BX, UK. s.s.keller@liv.ac.uk <s.s.keller@liv.ac.uk>
Cresswell
Paul
P
Denby
Christine
C
Wieshmann
Udo
U
Eldridge
Paul
P
Baker
Gus
G
Roberts
Neil
N
D000328:Adult; D001921:Brain / Q000473:pathology* / Q000503:physiopathology*; D004569:Electroencephalography; D004833:Epilepsy, Temporal Lobe / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery*; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009483:Neuropsychological Tests; D019635:Neurosurgical Procedures; D012640:Seizures / Q000209:etiology* / Q000473:pathology* / Q000503:physiopathology; D013686:Telemetry; D013702:Temporal Lobe / Q000601:surgery*; D016896:Treatment Outcome