46 year-old woman with refractory seizures since age 15

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Findings:

Diffuse band of abnormal tissue in the subcortical white matter that follows gray matter signal intensity and demonstrates multiple spicules of extension to the cortex

DDX:

Band heterotopia
Leukodystrophy

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Diagnosis:

Band heterotopia

Discussion:

Gray matter heterotopia are collections of nerve cells in abnormal locations secondary to arrest of radial migration of neurons. Although it may be confused in some cases with leukodystrophy, the abnormal tissue follows gray matter on all pulse sequences and the appearance is essentially pathognomonic. Patients with heterotopic gray matter almost always present with seizures. Heterotopia is often divided into three groups: subependymal , focal cortical and band. Band heterotopia is more commonly seen in females (90%).

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Submitted by Asako Miyakoshi, MD, UW Neuroradiology