Neuroradiological changes in neurocutaneous diseases: II tuberous sclerosis(TS), Sturge – Weber (S-W) syndrome, Hippel-Lindau (H-L) syndrome

Intracranial lesions in TS are characterized by the presence of cortical and subcortical hamartomas, subependimal periventricul nodules, giant-cell astrocitomas in subependimal areas, radial heterotopias inside the white matter of brain spreading from ventricles towards the subcortical area. Cortical and subcortical hamartomas can be multiple, but also solitary, frequently localized in the caput nuclei caudati and near the lateral ventricles. They can degenerate into giant-cell astrocitomas. CT signs of TS on native slices are typical multiple punctiform calcifications in the subependimal periventricular area without imbibition after the application of contrast. Lateral ventricles are often wider, as are the sulci on convexity. In the parenchyma there are hypo or hyperdense lesions with no compressive appearance. Hypodense lesions do not have imbibition, while hyperdense lesions can possibly have slight imbibition after contrast. MRI signs of hamartomas are hypo or isointensive lesions on T1 and hyperintensive on T2-weighted imaging. They are mostly localized in the frontal area or in the cerebellum and they can have imbibition after contrast. Subependimal nodules can have diverse imbibition after contrast. Classical neuroradiological changes in S-W syndrome are fusiform, tubular and serpentine calcifications that affect the brain cortex, usually unilateral occipital or occipito-parietal lobe, although both hemispheres can be affected. Usually there is hemyatrophy. On CT, the calcifications are also visible on the native images, and after the application of contrast there is imbibition because of pial angiomatosis. On MRI, the calcifications are visible as hypointensive changes on all sequences. GRE sequences are particularly sensitive to the detection of tiny calcifications. Brain atrophy is significant. Leptomeningas are thickened with expressed imbibition. White matter can have high signal on T2-weighted and FLAIR images because of the presence of gliosis.
A typical change of CNS in H-L syndrome is hemangioblastoma that presents itself as a cystic nodule localized in the cerebellum, medulla oblongata and medulla spinalis. MRI is the method of choice in diagnosis of hemangioblastoma. The mural nodule on T1 is iso- or hypointensive and on T2-weighted image it is hyperintensive. After the contrast, the nodule has intensive imbibition and the edges of the cyst can have slight imbibition or no imbibition at all. In 20% -40% of cases, the haemangioblastoma is a solid lesion with marked imbibition. CT signs – the hyperdense nodule with intratentorial localization on the native scan that has markedly good imbibition after contrast and always with a sharply limited hypodense lesion without imbibition.
Category: Abstracts
Volume: Vol. 52, No 3, july - september 2008
Authors: N. Bešenski
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