A proton magnetic resonance spectroscopy study of focal epilepsy in humans.

Localized in vivo proton magnetic resonance spectra obtained from diseased areas in 2 patients with chronic localized encephalitis (Rasmussen's syndrome) showed reduced resonance intensities from N-acetyl compounds, suggesting focally decreased N-acetylaspartate concentrations. One of the patients had epilepsia partialis continua secondary to the encephalitis. In this patient, the spectra demonstrated a high lactate resonance intensity (not seen in the normal, contralateral hemisphere) corresponding to an estimated local concentration of about 7.5 mM. We speculate that the observed decrease in the N-acetyl compound resonance may be a biochemical correlate of the neuronal loss characteristic of this disease. The results establish that excessive accumulation of lactate can occur in the human brain as a result of seizure activity even in the absence of ischemia. Thus, bioenergetic compromise may be 1 predisposing factor to the death of excitable cells in the epileptogenic area.