Figure 1: In this case, there is T1 isointense (top row left), FLAIR hyperintense (top row right, bottom row), nonenhancing signal within the left supramarginal and angular gyri subcortical white matter with overlying cortical thickening. While cortical dysplasia can be a difficult diagnosis to make, it most commonly is perisylvian in location, as is seen in this case.
Figure 2: Though 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.
- Often associated with refractory epilepsy
- Histologically classified based on giant dysmorphic neurons with or without balloon cells
- Age and Gender
- No gender predilection. Usually manifests in the first 2 decades of life with seizures
- 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
- Homogeneous T2 hyperintense comet-tail
- Imaging Recommendations
- Cortical dysplasia may mimic low grade glioma, depending on its location, size and configuration. Usually a triangular appearance with apex toward the ventricle is more characteristic of transmantle dysplasia. The cortical thickening and blurring of dysplasia may 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
Bronen RA, et al. Focal Cortical Dysplasia of Taylor, Balloon Cell Subtype: MR Differentiation from Low-Grade Tumors. AJNR. 1997; 18:1141-51.
Colombo N, et al. Focal Cortical Dysplasias: MR Imaging, Histopathologic, and Clinical Correlations in Surgically Treated Patients with Epilepsy. AJNR. 2003; 24:724-33.
Rastogi S, et al. Neuroimaging in Pediatric Epilepsy: A Multimodality Approach. Radiographics. 2008; 28:1079-95.
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