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Summary: Purpose: Recent studies have claimed that language functional magnetic resonance imaging (f MRI) can identify language lateralization in patients with temporal lobe epilepsy (TLE) and that f MRI-based findings are highly concordant with the conventional assessment procedure of speech dominance, the intracarotid amobarbital test (IAT). Methods: To establish the power of language f MRI to detect language lateralization during presurgical assessment, we compared the findings of a semantic decision paradigm with the results of a standard IAT in 68 patients with chronic intractable right and left temporal lobe epilepsy (rTLE, n = 28; lTLE, n = 40) who consecutively underwent a presurgical evaluation program. The patient group also included 14 (20.6%) subjects with atypical (bilateral or right hemisphere) speech. Four raters used a visual analysis procedure to determine the laterality of speech-related activation individually for each patient. Results: Overall congruence between f MRI-based laterality and the laterality quotient of the IAT was 89.3% in rTLE and 72.5% in lTLE patients. Concordance was best in rTLE patients with left speech. In lTLE patients, language f MRI identified atypical, right hemisphere speech dominance in every case, but missed left hemisphere speech dominance in 17.2%. Frontal activations had higher concordance with the IAT than did activations in temporoparietal or combined regions of interest (ROIs). Because of methodologic problems, recognition of bilateral speech was difficult. Conclusions: These data provide evidence that language f MRI as used in the present study has limited correlation with the IAT, especially in patients with lTLE and with mixed speech dominance. Further refinements regarding the paradigms and analysis procedures will be needed to improve the contribution of language f MRI for presurgical assessment. Key Words: Language f MRI—Temporal lobe epilepsy—Language lateralization—Intracarotid amobarbital test.

Functional imaging data suggest that the core network engaged in verbal semantic memory (SM) processing encompasses frontal and temporal lobe structures, with a strong left lateralization in normal right handers. The impact of long term temporal lobe epilepsy (TLE) on this network has only partly been elucidated. We studied verbal SM in 50 patients with chronic, intractable TLE (left TLE=26, right TLE=24) and 35 right handed normal controls using a verbal fMRI semantic decision paradigm. All patients had language lateralized to the left hemisphere, as verified by the intracarotid amobarbital procedure. Within and between group analyses showed remarkable, group-specific activation profiles. The control group activated frontal and temporal areas bilaterally, with a strong left predominance. Left TLE patients showed a shift of activations of left frontal and medial temporal areas to homologous regions in the right hemisphere. Furthermore, left TLE subjects utilized subcortical structures such as the thalamus and putamen to accomplish the verbal SM task. Contrastively, the activation pattern of right TLE patients resembled that of normal controls, but exhibited "hypofrontality" with a shift from frontal to posterior regions in the temporal, parietal and occipital lobe. Our results show that chronic epileptic activity originating from temporal seizure foci is associated with an alteration of neural circuits which support semantic language processing and that side of seizure focus has a specific impact on the resulting activation network. These findings presumably result from morphological changes and from functional reorganization which are both inherent to chronic TLE.

Impairments of memory are often found after rupture and repair of aneurysms leading to a basal forebrain lesion. This open study investigated whether cholinergic substitution therapy may be a treatment option. The effect of donepezil, a cholinesterase inhibitor on memory functions was tested in an open-label, exploratory study in 11 patients with a chronic amnestic syndrome from a ruptured and repaired aneurysm of the anterior communicating artery (seven patients), the anterior cerebral (two) or the pericallosal artery (two). Mean time since onset was 75.4 months. Memory was evaluated at baseline and consecutively after 4 weeks of 5 mg donepezil daily, 8 weeks of 10 mg donepezil, and 4 weeks after drug discontinuation. Memory functions were assessed using the California Verbal Learning Test and compared with a matched group of normal, untreated controls. Tests of attention and of executive functions were also administered. Donepezil was well tolerated. Strong group effects were found at baseline and at all follow-up measurements showing profound impairments of memory functions in the patient group. Within patient statistics showed significant improvements of short and long delay free recall scores during the treatment period, both with 5 and 10 mg donepezil daily, whereas attentional and executive functions improved only non-significantly. Memory functions decreased after drug discontinuation. Repeated test administration in the control group also showed an increase of memory scores which was minor when compared with the performance change in the patient group. Donepezil may improve episodic memory functions in patients suffering from a chronic amnestic syndrome caused by rupture and repair of aneurysms of the anterior communicating, the anterior cerebral or the pericallosal artery. Future doubled-blind, placebo-controlled trials are warranted to confirm these findings.

Medial temporal lobe (MTL) areas are well known to serve episodic memory functions; their contribution to semantic memory has been occasionally noticed but not studied in detail. In the present fMRI study, 35 right-handed and 35 left-handed healthy subjects performed a semantic decision paradigm during which subjects heard spoken concrete nouns designating objects and had to decide on whether these objects were available in the supermarket and cost lest then a certain amount of money. The control paradigm consisted of sequences of low and high tones where subjects had to decide whether a sequence contained two high tones. The resulting contrast activation of semantic decision versus tone decision involved neocortical temporal, parietal, and prefrontal areas. Additional significant, bilateral activations in the MTL, the hippocampal formation, and adjacent areas were found. The exact incidence and location of activation was studied in a single-subject analysis for all 70 subjects. At the chosen threshold of P