Walsh & Hoyt: Neuroimaging

Neuroimaging techniques have increased the recognition of tuberous sclerosis. In one study, cranial CT scans in 26 patients showed subependymal nodules in 96% and cortical tubers in 54%. The nodules were calcified in 88% and the tubers in 54%. MR imaging can also be used to detect the intracranial lesions in tuberous sclerosis. In the study of 26 patients mentioned above, MR imaging showed subependymal nodules in 63% and cortical tubers in 94%. The sensitivity of MR imaging in identifying these lesions increases when special techniques such as FLAIR or magnetization transfer are used. MR imaging also identifies four types of white-matter lesions in tuberous sclerosis: straight or curvilinear bands extending from the ventricle to the cortical mantle, wedge-shaped lesions, nonspecific conglomerate foci, and cerebellar radial bands. About 25% of patients also have abnormalities in the cerebellum by MR imaging. Contrast enhancement with MR imaging is frequently observed in both subependymal nodules and white-matter lesions. Consequently, contrast enhancement of a subependymal nodule does not indicate a malignant transformation. Tubers are more common in patients with infantile spasms whose first seizure occurs in the first year of life or who are mentally retarded.