Is the intracellular pH different from normal in the epileptic focus of patients with temporal lobe epilepsy? A P-31 NMR study

We performed in vivo P-31 NMR spectroscopic studies of human brain on a 4.1 T whole-body NMR system. Based on a control group of 20 healthy volunteers, the normal pH(i) was 7.05 (SD, 0.06; SEM, 0.01) in the left temporal lobe and 7.04 (SD, 0.04; SEM, 0.01) in the right temporal lobe. We also studied a patient group consisting of 13 individuals with unilateral temporal lobe epilepsy. The mean pH(i) was 7.02 (SD, 0.04; SEM, 0.01) in the ipsilateral lobe and 7.02 (SD, 0.05; SEM, 0.01) in the contralateral lobe. These results clearly show that no statistically significant difference in pH(i) is observed between the two lobes, either in normal controls or in patients. Also, no significant pH(i) difference exists between the control group and the patient group. Lateralization in each of the 13 patients with unilateral epilepsy, based on their individual pH(i) difference between the ipsilateral lobe and contralateral lobe (Delta pH(i)), showed that three patients were nondiagnostic cases because their Delta pH(i)s were not significantly different from zero (less than or equal to 0.02), five patients showed small Delta pH(i)s consistent with their clinical lateralization, whereas the remaining five patients showed Delta pH(i)-based lateralization opposite to the clinical findings. These results seem to indicate an essentially random distribution around Delta pH(i) = 0 within a very small experimental error of +/- 0.02 pH units. pH(i) obtained from eight different areas in each of the 13 unilateral patients also did not show any significantly nonzero Delta pH(i) values. These results led to the conclusion that even at the excellent spectral resolution and reproducibility of the 4.1 T machine (typical SD of 0.05 pH units), no significant pH(i) effect, induced by temporal lobe epilepsy, could be detected. Therefore, in this study, Delta pH(i) does not appear to be a clinically useful tool for the lateralization of epileptic foci in patients with temporal lobe epilepsy.