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

Abstract

Summary:Purpose: To assess the biochemical properties of band heterotopia in comparison with other cortical developmental malformations (CDMs) by using proton magnetic resonance spectroscopy ( 1 H-MRS).Methods: We performed localized single-voxel 1 H-MRS studies on 13 patients [five band heterotopia (BH), two focal cortical dysplasia (CD), two unilateral CD, one bilateral perisylvian dysplasia, three hemimegalencephaly]. CDMs other than BH were categorized as CD. Spectra were acquired from volumes of interest (VOIs) localized in the CD and in normalappearing cortex on the contralateral side. In BH patients, the VOIs were the external cortex and the laminar heterotopia. For the BH study, spectra also were obtained from the cortex of age-matched normal volunteers.Results: The spectra of CD lesions were characterized by significantly lower ratios of N-acetyl aspartate to creatine (NAA/Cr) and by higher choline to Cr (Cho/Cr) ratios than in the contralateral remote cortex (p ‫ס‬ 0.01 and 0.01, respectively). The NAA/Cr and Cho/Cr ratios of the external cortex of BH were not significantly different from those of normal volunteers. The NAA/Cr ratio of the laminar heterotopia was not significantly different from that of the external cortex (p ‫ס‬ 0.12) or normal volunteers (p ‫ס‬ 0.60), whereas Cho/Cr was significantly higher in laminar heterotopias than in the external cortex (p ‫ס‬ 0.04) or controls (p ‫ס‬ 0.03).Conclusions: 1 H-MRS can distinguish between the metabolic properties of BH and CD.

Multivoxel Proton MR Spectroscopy in Malformations of Cortical Development

“…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 ). This larger voxel may be influenced more intensely by partial volume averaging, and that could potentially affect the sensitivity of the method to subtle abnormalities.…”

“…One of the studies 29 found reduced NAA/Cr only in cortical dysplasia. An in vitro MR spectroscopy study also showed decreased NAA in surgical biopsies of cortical dysplasias.…”

“…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.…”

Sensorimotor organization in double cortex syndrome

“…In a study using diffusion tractography, similar patterns of connectivity were found in patients with heterotopia and in control subjects [Eriksson et al, 2002]. Moreover, magnetic resonance spectroscopy studies [Iannetti et al, 2001;Munakata et al, 2003] have shown normal amounts of the neuronal marker N-acetyl aspartate in the heterotopic band, and PET studies [De Volder et al, 1994;Miura et al, 1993] demonstrated that the subcortical band has a glucose metabolism comparable to that of the overlying normotopic cortex, suggesting preserved neuronal and axonal integrity. Although we cannot formally exclude the possibility that common vascular factors are shared between the normoand heterotopic cortices, the fact that the band is distant from the sulci and large vessels, as well as the size of activations we found in our patients, are more in keeping with neuronal activation.…”

Disrupted Frontal Connections in Band Heterotopia Mapped by Diffusion Tensor Tractography

“…Currently, in vivo data on the connectivity of inner and outer white matter in BHT is still lacking, mainly because functional neuroimaging may not be able to reveal actual region-to-region connections [3,4]. Recent studies have shown that the inner heterotopic cortex may play an important role in the physiological function of the BHT brain [5][6][7][8]. However, the functional association or dissociation between the inner and outer overlying gray matter in BHT patients remains ambiguous.…”