NEURONAL METABOLIC DYSFUNCTION IN PATIENTS WITH CORTICAL DEVELOPMENTAL MALFORMATIONS - A PROTON MAGNETIC-RESONANCE SPECTROSCOPIC IMAGING STUDY

Cortical developmental malformations are best diagnosed by MRI and are often the cause of refractory epilepsy. Little is known about the met abolic cell function on MR spectroscopy of these types of brain anomal y. We studied 23 patients with cortical developmental malformations an d refractory epilepsy using proton MR spectroscopic imaging. Mean age was 28 years (range, 9 to 47 years). The lesions examined were focal c ortical dysplasia (n = 5), heterotopia (four band, six periventricular , two subcortical), polymicrogyria (n = 3), tuberous sclerosis (n = 2) , and polymicrogyria and periventricular nodular heterotopia (n = 1). We measured the relative signal intensity of N-acetylaspartate/creatin e (NAA/Cr) in the lesion, in the perilesional region, and in the regio n remote from the visible lesion. The values were compared with those from similar brain regions of 25 normal control subjects. The mean NAA /Cr z score values for the 23 patients were as follows: lesion, -2.20 +/- 0.32 (mean +/- SE), n = 21; perilesional region, -1.01 +/- 0.38, n = 15; and distant region, -0.03 +/- 0.34, n = 18 (p < 0.0002). Despit e the presence of a large number of neurons, heterotopia showed a rela tive decrease of NAA in some patients, suggesting that the neurons pre sent were dysfunctional. The maximal NAA/Cr decrease, indicating metab olic dysfunction, colocalized to the structural malformation as define d by MRI and extended to normal-appearing regions adjacent to the visi ble lesion.