Magnetic resonance spectroscopy of the thalamus in patients with mesial temporal lobe epilepsy and hippocampal sclerosis.

PURPOSE: to investigate potential neuronal dysfunction within the thalamus in patients suffering from mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE/HS). METHODS: we examined twenty epileptic patients suffering from mesial temporal lobe epilepsy with hippocampal sclerosis (17 females, 3 males) and twenty sex- and age-matched healthy controls. H MR spectroscopic imaging (SI) was performed over the right and left thalamus in all patients and controls. In addition both hippocampi were investigated by the H MR spectroscopic single voxel (SV) technique in both groups. RESULTS: statistical analysis of compared data in both groups demonstrated that the total thalamic NAA level was significantly decreased in patients with MTLE/HS as compared to healthy controls. Detailed analysis revealed a statistically significant reduction of NAA, NAA/Cr and NAA/(Cr+Cho) ratios in the thalamus ipsilateral to hippocampus affected with hippocampal sclerosis in patients compared to controls, while no significant changes were observed in the thalamus contralateral to sclerotic hippocampus. A comparison of values in ipsilateral and contralateral thalami in patients showed statistically significant difference with lower values of NAA and both ratios in the ipsilateral thalamus. Previously reported reduced hippocampal concentration of NAA, NAA/Cr and NAA/(Cr+Cho) ratios on the side of hippocampal sclerosis compared with contralateral hippocampus in patients and both hippocampi in controls was confirmed. CONCLUSIONS: the present MRS data clearly indicate neuronal dysfunction within the thalamus ipsilateral to the sclerotic hippocampus of patients with mesial temporal lobe epilepsy. In agreement with other recent functional and structural neuroimagings our results confirm the role of the ipsilateral thalamus in the medial temporal/limbic epileptic network.

Magnetic resonance spectroscopy of the thalamus in patients with typical absence epilepsy.

PURPOSE: To investigate possible neuronal dysfunction of the thalamus in patients suffering from typical absence epilepsy, using magnetic resonance spectroscopy (MRS). Special attention was paid to levels of N-acetylaspartate (NAA) and creatine (Cr), and to the NAA/Cr ratio. METHODS: MRS was performed over the right and left thalamus in nine patients suffering from typical absence epilepsy, and in nine sex- and age-matched healthy controls. All patients and controls were examined using a standard MRS-CSI (chemical shift imaging) technique. RESULTS: Statistical analysis of the obtained data demonstrated a significantly lower thalamic NAA/Cr ratio in patients with typical absence epilepsy when compared to the healthy controls. Our MRS data showed symmetrical distribution of NAA/Cr ratio in the right and left thalamus within both the patient group and the group of healthy controls. No significant correlation between the patients' thalamic NAA/Cr values and the duration of the epilepsy or seizure frequency was revealed. CONCLUSIONS: The present MRS data clearly indicate neuronal dysfunction in the thalami of patients with typical absence epilepsy. In agreement with other recent MRS findings in different idiopathic generalized epilepsy syndromes, our results confirm the role of the thalamus as an important structure in the pathogenesis of typical absence epilepsy.