Organization of receptive language-specific cortex before and after left temporal lobectomy.
OBJECTIVE
To examine brain activation associated with receptive language in patients with left temporal lobe epilepsy (TLE) before and after an anterior temporal lobectomy using magnetoencephalography (MEG), and to evaluate which patients were most likely to show a change in the lateralization and localization of the mechanisms supporting receptive language and if such changes were associated with neuropsychological function.


METHODS
Twelve patients with left TLE underwent preoperative Wada testing, and pre- and postoperative neuropsychological testing and MEG language mapping. The anatomic location of receptive language-related activity sources observed with MEG was determined by coregistering MEG data with structural MRI scans. Language laterality indices were calculated based on the number of reproducible activity sources in each hemisphere. The proximity of language-specific activity sources to Wernicke's area was also examined.


RESULTS
Although the small sample size precluded formal statistical analyses, patients with atypical (bilateral) hemispheric dominance preoperatively were more likely than patients with typical (left-hemisphere) dominance to show evidence of increased right hemisphere participation in language functions after surgery. Patients with left hemispheric dominance preoperatively were more likely to show intrahemispheric changes involving a slight inferior shift of the putative location of Wernicke's area. Patients with bilateral representation tended to perform worse on neuropsychological test measures obtained both pre- and postoperatively.


CONCLUSIONS
Interhemispheric functional reorganization of language-specific areas may occur in patients undergoing left anterior temporal lobectomy. Intrahemispheric reorganization may take place even when the resection does not directly impinge upon Wernicke's area.
Pataraia
E
E
Department of Neurosurgery, Vivian L. Smith Center for Neurologic Research, University of Texas-Health Science Center at Houston, Houston, TX 77030, USA. ekaterina.pataraia@meduniwien.ac.at
Billingsley-Marshall
R L
RL
Castillo
E M
EM
Breier
J I
JI
Simos
P G
PG
Sarkari
S
S
Fitzgerald
M
M
Clear
T
T
Papanicolaou
A C
AC
D000654:Amobarbital / Q000008:administration & dosage; D038481:Anterior Temporal Lobectomy / Q000009:adverse effects; D001931:Brain Mapping / Q000379:methods*; D002339:Carotid Arteries; D004292:Dominance, Cerebral; D004833:Epilepsy, Temporal Lobe / Q000503:physiopathology*; D005071:Evoked Potentials; D005260:Female; D006801:Humans; D007269:Injections, Intra-Arterial; D007802:Language; D007807:Language Tests; D015225:Magnetoencephalography; D008297:Male; D009473:Neuronal Plasticity; D009483:Neuropsychological Tests; D011184:Postoperative Period; D013702:Temporal Lobe / Q000503:physiopathology*; D014706:Verbal Learning
D000654:Amobarbital