Metabolic Changes in Neuronal Migration Disorders: Evaluation by Combined MRI and Proton MR Spectroscopy

Abstract

Summary: Purpose: To assess the role of 'H-magnetic resonance spectroscopy (MRS) in detecting biochemical abnormalities in neuronal migration disorders (NMDs).Methods: We performed 'H-MRS studies on 17 brain NMD areas [five polymicrogyria, eight subcortical heterotopia, and four cortical dysplasia on magnetic resonance imaging (MRI)]. The study group consisted of I5 patients, all but one affected by partial epileptic seizures. Spectra were acquired from volumes of interest localized on NMDs and contralateral sides and compared with those obtained on gray and white matter of 18 neurologic controls.Results: NMD lesions were characterized by lower Nacetylaspartate to creatine (NAAICr) and choline to Cr (Chot Cr) ratios than those of the white (p = 0.002 and p = 0.004) and gray matter (p = 0.03 and p = 0.06) of neurologic controls. In addition, the nonnal-appearing contralateral sides to the NMD lesions showed a significant decrease of Cho/Cr ratio when compared with those of white (p = 0.003) and gray matter (p = 0.05) of neurologic controls. No relation was found between NAAlCr decrease, EEG abnormalities, and NMD sides, or between NANCr ratios, duration of epilepsy, and frequency of seizures. Lactate signal was detected in the spectra of four patients who had an epileptic seizure a short time before MR examination.Conclusions: NAA/Cr decrease may be related more to structural and functional alteration of the NMD sides than to epileptic activity in these lesions. Low Cho/Cr may be related to a more extensive diffuse hypomyelination than suggested by the MRI findings. An activation of anerobic glycolysis during and after seizures could account for the presence of lactate. These data confirm that 'H-MRS is an advanced technique that may provide useful biochemical information in vivo on neurobiologic processes underlying NMDs. Key Words: Neuronal migration disorders-Epilepsy-Proton magnetic resonance spectroscopy-Magnetic resonance imaging.Neuronal migration disorders (NMDs) are a broad group of brain illnesses characterized by anomalies of site, thickness, shape, and organization of cerebral cortex due to a complete or partial failure of the neuroblast migration process, which may occur between the gestational weeks 8 and 15 (1,2). The etiology of NMD is extremely varied and may include genetic and chromosomal factors or maternal and environmental causes (for example, toxic, infectious, and hypoxichschemic) (3).Several clinical studies reported that frequently NMDs are associated with severe partial epilepsy, suggesting a combination of morphologic and functional abnormali-

Multivoxel Proton MR Spectroscopy in Malformations of Cortical Development

“…In 11 of these articles, the metabolite ratios obtained in the lesion were compared with those in a control group, and in 9 articles, the NACS was also studied. 9,19,20,[24][25][26][27]29 The abnormality most frequently found in MCD was decreased NAA or NAA/Cr in the lesion compared with a that in the control group, 9,20,[22][23][24]27,28,31 in agreement with our results, but some articles reported cases presenting a normal NAA peak in MCD compared with that in a control group. 21,29,30 This observation might be explained by the fact that these authors used single-voxel MR spectroscopy with a larger voxel volume size (3-8 cm 3 ) than the one used in our study (2.25 cm 3 ).…”

“…Examinations were not performed within 48 hours of the last seizure, except in 4 patients who had daily episodes. This procedure was adopted because of the previous evidence of the presence of a lactate peak in the spectra of patients with MCD who experienced seizures a short time before MR spectroscopy acquisition, 9 probably reflecting anaerobic glycolysis during and after seizures.…”

“…5 Previous published studies about MR spectroscopy and MCD are very different in the number of cases and methodologies used. 9,[19][20][21][22][23][24][25][26][27][28][29][30][31] Of these studies, 8 used single-voxel MR spectroscopy and 6 used multivoxel MR spectroscopy. Six are case reports, and in the remaining 8 articles, the number of patients studied varied from 8 to 31.…”

Metabolic Properties of Band Heterotopia Differ from Those of Other Cortical Dysplasias: A Proton Magnetic Resonance Spectroscopy Study

“…A previous article reported that the Cho signal is decreased in the CD area (18). Although the reason for this discrepancy remains unknown, a possible explanation may lie in the difference in the age of the patients.…”

Metabolic characteristics of cortical malformations causing epilepsy

“…Therefore, NAA reductions might also be helpful for a better delineation of structural and functional abnormal regions in CMs and the surrounding normal appearing tissue. This assumption is supported by the fact that the most consistent finding of the limited number of MRS studies in CMs has indeed been a reduction of NAA [6,13,[17][18][19]26,31]. However, considering the fact that MRI visible CMs usually contain abnormal neuronal elements and are characterized by severe disturbances of the histological architecture, metabolic abnormalities are probably not restricted to NAA but affect also creatine/ phosphocreatine (Cr) and choline compounds (Cho).…”