Combined Measurements of Hippocampal N‐Acetyl‐Aspartate and T₂ Relaxation Time in the Evaluation of Mesial Temporal Lobe Epilepsy: Correlation with Clinical Severity and Memory Performances

Abstract

Summary:Purpose: In this study we tried to find a correlation between the clinical severity and memory performances, by comparing proton magnetic resonance (MR) spectroscopy and T, relaxation time measurements in the hippocampi, in a homogeneous group of 27 patients with unilateral mesial temporal lobe epilepsy with ipsilateral hippocampal sclerosis on MR imaging, with a view to answer the following questions: (a) how sensitive is this approach for the assessment of the apparently normal contralateral hippocampus, (b) do the results relate to the clinical severity, and (c) does it allow evaluation of the degree of hippocampal dysfunction.Methods: Volume-selective proton MR spectroscopy of the head of both hippocampi was performed at 3 T, by using the PRESS sequence, with an echo time of 135 ms, to estimate NAA/(Cho + Cr) ratios. The relaxation times were measured at 0.28 T, by using a conventional Carr-Purcell-Meiboom-Gill sequence, with a repetition time of 2,000 ms, an echo time of 15 ms, and 48 echoes. Conclusions: We showed that the combination of NAA and T, relaxation time measurements can be used to examine the degree of ipsi-and contralateral hippocampal dysfunction or injuries and their relations with memory performances in the presurgical evaluation of patients. Key Words: EpilepsyTemporal lobe-Hippocampus-Magnetic spectroscopyMagnetic resonance imaging.Mesial temporal sclerosis, characterized by selective neuronal loss and reactive gliosis in the hippocampus and other mesial temporal structures, is a common pathologic finding in mesial temporal lobe epilepsy (mTLE). Within the past 10 years, the reliable identification of

Correlation between 1H MRS and Memory before and after Surgery in Mesial Temporal Lobe Epilepsy with Hippocampal Sclerosis

“…Although a correlation between the material-specific memory and 1 H MRS values was claimed to be demonstrated in the previous studies, as (9).…”

“…Therefore some authors advised increasing the number of nonverbal memory tests (8,10). To overcome the same problem, Namer et al (9) added another parameter (i.e., T 2 relaxation time measurements).…”

Idiopathic generalised epilepsy: a pilot study of memory and neuronal dysfunction in the temporal lobes, assessed by magnetic resonance spectroscopy

“…As no previous study correlating neuropsychological variables with MRS variables in patients with IGE has been published, the sample size was chosen to be similar to that of other studies that have used correlational analysis of magnetic resonance data and cognitive variables. 24 Epilepsy assessment The Chalfont Severity of Seizures Scale 25 was used to assess the effect of each type of seizure on the patient's life. Total lifetime number of each type of seizure was estimated by the patient in consultation with JMD, who had access to the patient's medical records.…”

Magnetoencephalographic and Magnetic Resonance Spectroscopy Evidence of Regional Functional Abnormality in Mesial Temporal Lobe Epilepsy

“…We and others have shown MRS to be highly sensitive and able to detect metabolic abnormalities even when cell loss is below the threshold for MRI-detectable pathology (Shih et al 2004). In addition, there is a correlation between decrease in metabolites detected by MRS and clinical impairment in epilepsy (Namer et al 1999;Gilliam et al 2007). MRS may therefore provide an indication of regional pathology that differs from the more focal pathology visualized on MRI (Connelly et al 1994).…”