Abstracts

RATIONALE: Ictal fear is most frequently elicited by epileptic discharges from mesial temporal areas, predominantly the amygdala and the anterior hippocampal region. We aimed to assess by means of MR spectroscopy whether (i) patients with ictal fear show more anteriorly pronounced metabolic changes along the hippocampal axis compared to patients without ictal fear and whether (ii)patients with ictal fear represent a supgroup with a better outcome after temporal lobectomy than other patient groups. METHODS: 1H multivoxel magnetic resonance spectroscopy of the hippocampal formation was applied on 33 patients with medically intractable temporal lobe epilepsy and typical features of hippocampal and / or amygdala sclerosis on routine MRI. Presence or absence of ictal fear as well as surgical outcome (mean follow up period: 25 months) was assessed in all patients. Different distribution patterns of metabolic abnormalities were compared between patient groups with and without ictal fear. RESULTS: 12 of the 33 patients (36%) reported of fear at the beginning of their habitual seizures. 11 of these patients were seizure free. In contrast, only 11 of 21 patients without ictal fear had a favorable outcome. MR spectroscopy revealed significantly higher pathological NAA / Cho ratios in the anterior portion of the hippocampal formation in patients with ictal fear than in those without ictal fear, indicating focal metabolic and / or morphologic changes in the head of the hippocampus. CONCLUSIONS: These results indicate the importance to question the patient with respect to ictal fear in order to provide a more detailed prognosis of the surgical outcome. In addition, our data emphasize that multivoxel MR spectroscopy is a valuable tool in the presurgical evaluation as it may reveal different topographical patterns of hippocampal sclerosis.