Cognitive correlates of 1H MRSI-detected hippocampal abnormalities in temporal lobe epilepsy

Objectives: To examine associations between H-1 magnetic resonance spectroscopic imaging (H-1 MRSI)detected hippocampal creatine to N-acetylaspartate (Cr/NAA) ratios and neuropsychological measures sensitive to mesial temporal lobe function. Background: The measurement of H-1 MRSI-detected hippocampal metabolites has proved effective in determining extent and lateralization of neuronal damage. However, relationships between H-1 MRSI-detected hippocampal metabolic abnormalities and specific areas of cognitive functioning have received limited attention compared to other studies using MRI volumetry or cerebral blood now techniques. Methods: We analyzed right and left hippocampal Cr/NAA ratios in 46 adult mesial temporal lobe epilepsy patients (32 left, 14 right) by H-1 MRSI at high magnetic field (4.1 T). We examined the relationship between the right and left Cr/NAA hippocampal ratios to measures of verbal and visual memory, intelligence, attention, visuoperception, and confrontation naming. Results: Measures of episodic verbal memory (n = 33) and visual confrontation naming (n = 46) were selectively associated with left hippocampal metabolic function (p < 0.004), whereas neuronal function of the right hippocampal region was strongly associated with performance on a measure of facial recognition (n = 46; p < 0.02). Conclusions: This study shows that specific areas of cognitive function are related to hippocampal neuronal metabolic abnormalities as detected by spectroscopic imaging. The current study indicates that H-1 MRSI offers a complimentary technique to structural imaging studies in the study of mesial temporal lobe epilepsy and may enhance understanding of the role of hippocampal function in complex cognitive systems.