Heterotopic Gray Matter
Heterotopic gray matter is caused by arrested migration of neurons from periventricular germinal zone to cortex. It can be inherited or acquired (maternal trauma, infection or toxin). It can be band-like (laminar) (Figure A) or nodular (Figure B). Nodular heterotopias can be focal or diffuse. Subependymal heterotopias are the most common, seen as nodules indenting the ventricles. Heterotopic gray matter is isodense with gray matter on CT and isointense with gray matter on MRI. Band heterotopias resemble double cortex, the inner heterotopic band may be thick or thin and continuous or discontinuous. Overlying cortex may be dysplastic or it may be normal, depending on the amount of heterotopic gray matter. Calcification is very rarely seen in the heterotopic gray matter.
Figure : Heterotopic Gray Matter. A, Axial MR image showing a band of heterotopic gray matter bilaterally (Arrows) with thin overlying cortex, giving an appearance of double cortex. B, Axial MR image showing subependymal nodular heterotopic gray matter (Arrows) lining both lateral ventricles.
Heterotopic gray matter is caused by arrested migration of neurons from periventricular germinal zone to cortex. It can be inherited or acquired (maternal trauma, infection or toxin). It can be band-like (laminar) (Figure A) or nodular (Figure B). Nodular heterotopias can be focal or diffuse. Subependymal heterotopias are the most common, seen as nodules indenting the ventricles. Heterotopic gray matter is isodense with gray matter on CT and isointense with gray matter on MRI. Band heterotopias resemble double cortex, the inner heterotopic band may be thick or thin and continuous or discontinuous. Overlying cortex may be dysplastic or it may be normal, depending on the amount of heterotopic gray matter. Calcification is very rarely seen in the heterotopic gray matter.
Figure : Heterotopic Gray Matter. A, Axial MR image showing a band of heterotopic gray matter bilaterally (Arrows) with thin overlying cortex, giving an appearance of double cortex. B, Axial MR image showing subependymal nodular heterotopic gray matter (Arrows) lining both lateral ventricles.
(A)
(B)The Internet Journal of Radiology™ ISSN: 1528-8404
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