Magnetic resonance spectroscopy in focal epilepsy: 31P and 1H spectroscopy.

Magnetic resonance spectroscopy (MRS) is rapidly becoming a clinical and research tool in epilepsy. Animal studies have demonstrated metabolic abnormalities in the interictal and ictal state showing energy depletion and changes in neuronal compounds. Similarly, clinical studies have demonstrated consistent abnormalities involving energy (31P) and cellular dependent (1H) compounds. Phosphorus MRS (31P) shows lateralizing metabolic dysfunction in approximately 65-75 p. 100 of patients with temporal lobe epilepsy (PCr/Pi). Proton MRS (1H) using single-voxel or chemical shift imaging has demonstrated a high sensitivity in lateralizing temporal lobe epilepsy (65-96 p. 100) with bilateral changes seen in 35-45 p. 100 of patients. The role of MRS in extra-temporal lobe epilepsy is less accurate because of the spatial limitations of current techniques. Further advances in this field promise to improve the clinical utility of MRS in epilepsy.