Abstracts

Rationale: Functional MRI (fMRI) studies on patients with hippocampal sclerosis and mesial temporal lobe epilepsy (mTLE) suggest lateralisation of visuo-spatial memory and facial emotion fMRI activation to the healthy side. We aimed to assess visuo-spatial memory and facial emotion processing in patients with mTLE and apical temporal lobe (aTL) dysplasia.Methods: Seventeen patients (8 women; median age 35 years, range 28-38) with mTLE due to unilateral probable aTL dysplasia were tested with two fMRI tasks: Roland s Hometown Walking Task (mental navigation and recall of familial visuo-spatial landmarks) and dynamic fearful faces paradigm (short movie with alternating images of landscape and faces expressing fear). All patients underwent neuropsychological assessment including Ekman Faces Test an instrument for testing recognition of basic facial emotions. Median age at seizure onset was 24 years (range 16-31), median epilepsy duration - 6 years (range 4-15). Fourteen patients (82%) had pharmacoresistant seizures; sixteen (94%) were right-handed. All patients underwent at least two high resolution MRI (1.5T) with an interval of at least six months. None of the patients had hippocampal sclerosis or any other structural cerebral abnormality.Results: In 15/17 (88%) patients, bilateral symmetrical fMRI activation of hippocampal and parahippocampal (H-PH) areas was observed in Roland s Hometown Walking Task. Eleven patients (65%) with left-sided probable aTL dysplasia had bilateral H-PH activation; one patient had activation of left H-PH areas and another one of right H-PH areas. All four patients with right-sided probable aTL dysplasia had bilateral symmetrical fMRI activation of H-PH. fMRI activation in amygdalae (fearful faces paradigm) was elicited in 8/17 (47%) patients. In patients with left-sided probable aTL dysplasia (n=13), ipsilateral (n=3), contralateral (n=3), bilateral activations (n=1) and no activation in amygdalae (n=6) were observed. Patients with right-sided probable aTL dysplasia (n=4) showed ipsilateral (n=1) or no activation in amygdalae (n=3). Conclusions: Hippocampus and parahippocampal area are involved in visual memory retrieval in the majority of patients with probable aTL dysplasia. However, amygdalae are activated only in a limited number of these patients and the shift of function from dysplastic amygdala to the contralateral side might occur.