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Cortical Dysplasia

Last Updated: July 5, 2021

Open Table of Contents: Cortical Dysplasia

Figure 1: In this case, there is T1-isointense (top left), FLAIR-hyperintense (top right and bottom), nonenhancing signal within the left supramarginal and angular gyri subcortical white matter with overlying cortical thickening. Although cortical dysplasia can be a difficult diagnosis to make, it most commonly is perisylvian in location, as is seen in this case.

Figure 1: In this case, there is T1-isointense (top left), FLAIR-hyperintense (top right and bottom), nonenhancing signal within the left supramarginal and angular gyri subcortical white matter with overlying cortical thickening. Although cortical dysplasia can be a difficult diagnosis to make, it most commonly is perisylvian in location, as is seen in this case.

Figure 2: Although the Blumke classification is a pathologic classification, imaging occasionally will have features that are characteristic of type II cortical dysplasia (Taylor type). Notice the cortical and subcortical FLAIR-hyperintense and TI-hypointense signal with associated mild cortical expansion and a thin linear focus of FLAIR-hyperintense signal radiating toward the ventricle. This radiating signal is referred to as the transmantle sign.

Figure 2: Although the Blumke classification is a pathologic classification, imaging occasionally will have features that are characteristic of type II cortical dysplasia (Taylor type). Notice the cortical and subcortical FLAIR-hyperintense and TI-hypointense signal with associated mild cortical expansion and a thin linear focus of FLAIR-hyperintense signal radiating toward the ventricle. This radiating signal is referred to as the transmantle sign.

Description

  • Often associated with refractory epilepsy

Pathology

  • Histologically classified based on giant dysmorphic neurons with or without balloon cells

Clinical Features

  • Symptoms
    • Refractory epilepsy
  • Age and gender
    • No gender predilection; usually manifests in the first 2 decades of life with seizures

Imaging

  • General
    • Thickening, blurring, and sometimes hyperintensity of the cortex
    • Abnormal signal may be seen to extend from the cortex to the ventricle with tapering as it approaches the lateral ventricle
  • Modality specific
    • CT
      • Usually normal
    • MRI
      • T1WI
        • Slightly hypointense
      • T2WI/FLAIR
        • Homogeneous T2-hyperintense comet-tail
      • Contrast
        • Typically nonenhancing
  • Imaging recommendations
    • MRI with contrast
  • Mimic
    • Cortical dysplasia can mimic low-grade glioma, depending on its location, size, and configuration. Usually a triangular appearance with the apex toward the ventricle is more characteristic of transmantle dysplasia. The cortical thickening and blurring of dysplasia can be much more difficult to distinguish from low-grade tumor such as ganglioglioma.

For more information, please see the corresponding chapter in Radiopaedia.

Contributor: Sean Dodson, MD

DOI: https://doi.org/10.18791/nsatlas.v1.03.02.12

References

Bronen RA, Vives KP, Kim JH, et al. Focal cortical dysplasia of Taylor, balloon cell subtype: MR differentiation from low-grade tumors. AJNR Am J Neuroradiol 1997;18:1141–1151.

Colombo N, Tassi L, Galli C, et al. Focal cortical dysplasias: MR imaging, histopathologic, and clinical correlations in surgically treated patients with epilepsy. AJNR Am J Neuroradiol 2003;24:724–733.

Rastogi S, Lee C, Salamon N. Neuroimaging in pediatric epilepsy: a multimodality approach. Radiographics 2008;28:1079–1095. doi.org/10.1148/rg.284075114

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